# Embedding a Tweet Can be Copyright Infringement, Court Rules

Post Syndicated from Ernesto original https://torrentfreak.com/embedding-a-tweet-can-be-copyright-infringement-court-rules-180216/

Nowadays it’s fairly common for blogs and news sites to embed content posted by third parties, ranging from YouTube videos to tweets.

Although these publications don’t host the content themselves, they can be held liable for copyright infringement, a New York federal court has ruled.

The case in question was filed by Justin Goldman whose photo of Tom Brady went viral after he posted it on Snapchat. After being reposted on Reddit, it also made its way onto Twitter from where various news organizations picked it up.

Several of these news sites reported on the photo by embedding tweets from others. However, since Goldman never gave permission to display his photo, he went on to sue the likes of Breitbart, Time, Vox and Yahoo, for copyright infringement.

In their defense, the news organizations argued that they did nothing wrong as no content was hosted on their servers. They referred to the so-called “server test” that was applied in several related cases in the past, which determined that liability rests on the party that hosts the infringing content.

In an order that was just issued, US District Court Judge Katherine Forrest disagrees. She rejects the “server test” argument and rules that the news organizations are liable.

“[W]hen defendants caused the embedded Tweets to appear on their websites, their actions violated plaintiff’s exclusive display right; the fact that the image was hosted on a server owned and operated by an unrelated third party (Twitter) does not shield them from this result,” Judge Forrest writes.

Judge Forrest argues that the server test was established in the ‘Perfect 10 v. Amazon’ case, which dealt with the ‘distribution’ of content. This case is about ‘displaying’ an infringing work instead, an area where the jurisprudence is not as clear.

“The Court agrees with plaintiff. The plain language of the Copyright Act, the legislative history undergirding its enactment, and subsequent Supreme Court jurisprudence provide no basis for a rule that allows the physical location or possession of an image to determine who may or may not have “displayed” a work within the meaning of the Copyright Act.”

As a result, summary judgment was granted in favor of Goldman.

Rightsholders, including Getty Images which supported Goldman, are happy with the result. However, not everyone is pleased. The Electronic Frontier Foundation (EFF) says that if the current verdict stands it will put millions of regular Internet users at risk.

“Rejecting years of settled precedent, a federal court in New York has ruled that you could infringe copyright simply by embedding a tweet in a web page,” EFF comments.

“Even worse, the logic of the ruling applies to all in-line linking, not just embedding tweets. If adopted by other courts, this legally and technically misguided decision would threaten millions of ordinary Internet users with infringement liability.”

Given what’s at stake, it’s likely that the news organization will appeal this week’s order.

Interestingly, earlier this week a California district court dismissed Playboy’s copyright infringement complaint against Boing Boing, which embedded a YouTube video that contained infringing content.

A copy of Judge Forrest’s opinion can be found here (pdf).

Source: TF, for the latest info on copyright, file-sharing, torrent sites and more. We also have VPN discounts, offers and coupons

# Voksi Releases Detailed Denuvo-Cracking Video Tutorial

Post Syndicated from Andy original https://torrentfreak.com/voksi-releases-detailed-denuvo-cracking-video-tutorial-180210/

Earlier this week, version 4.9 of the Denuvo anti-tamper system, which had protected Assassins Creed Origin for the past several months, was defeated by Italian cracking group CPY.

While Denuvo would probably paint four months of protection as a success, the company would certainly have preferred for things to have gone on a bit longer, not least following publisher Ubisoft’s decision to use VMProtect technology on top.

But while CPY do their thing in Italy there’s another rival whittling away at whatever the giants at Denuvo (and new owner Irdeto) can come up with. The cracker – known only as Voksi – hails from Bulgaria and this week he took the unusual step of releasing a 90-minute video (embedded below) in which he details how to defeat Denuvo’s V4 anti-tamper technology.

The video is not for the faint-hearted so those with an aversion to issues of a highly technical nature might feel the urge to look away. However, it may surprise readers to learn that not so long ago, Voksi knew absolutely nothing about coding.

“You will find this very funny and unbelievable,” Voksi says, recalling the events of 2012.

“There was one game called Sanctum and on one free [play] weekend [on Steam], I and my best friend played through it and saw how great the cooperative action was. When the free weekend was over, we wanted to keep playing, but we didn’t have any money to buy the game.

“So, I started to look for alternative ways, LAN emulators, anything! Then I decided I need to crack it. That’s how I got into reverse engineering. I started watching some shitty YouTube videos with bad quality and doing some tutorials. Then I found about Steam exploits and that’s how I got into making Steamworks fixes, allowing cracked multiplayer between players.”

Voksi says his entire cracking career began with this one indie game and his desire to play it with his best friend. Prior to that, he had absolutely no experience at all. He says he’s taken no university courses or any course at all for that matter. Everything he knows has come from material he’s found online. But the intrigue doesn’t stop there.

“I don’t even know how to code properly in high-level language like C#, C++, etc. But I understand assembly [language] perfectly fine,” he explains.

For those who code, that’s generally a little bit back to front, with low-level languages usually posing the most difficulties. But Voksi says that with assembly, everything “just clicked.”

Of course, it’s been six years since the 21-year-old was first motivated to crack a game due to lack of funds. In the more than half decade since, have his motivations changed at all? Is it the thrill of solving the puzzle or are there other factors at play?

“I just developed an urge to provide paid stuff for free for people who can’t afford it and specifically, co-op and multiplayer cracks. Of course, i’m not saying don’t support the developers if you have the money and like the game. You should do that,” he says.

“The challenge of cracking also motivates me, especially with an abomination like Denuvo. It is pure cancer for the gaming industry, it doesn’t help and it only causes issues for the paying customers.”

Those who follow Voksi online will know that as well as being known in his own right, he’s part of the REVOLT group, a collective that has Voksi’s core interests and goals as their own.

“REVOLT started as a group with one and only goal – to provide multiplayer support for cracked games. No other group was doing it until that day. It was founded by several members, from which I’m currently the only one active, still releasing cracks.

“Our great achievements are in first place, of course, cracking Denuvo V4, making us one of the four groups/people who were able to break the protection. In second place are our online fixes for several AAA games, allowing you to play on legit servers with legit players. In third place, our ordinary Steamworks fixes allowing you to play multiplayer between cracked users.”

In communities like /r/crackwatch on Reddit and those less accessible, Voksi and others doing similar work are often held up as Internet heroes, cracking games in order to give the masses access to something that might’ve been otherwise inaccessible. But how does this fame sit with him?

“Well, I don’t see myself as a hero, just another ordinary person doing what he loves. I love seeing people happy because of my work, that’s also a big motivation, but nothing more than that,” he says.

Finally, what’s up next for Voksi and what are his hopes for the rest of the year?

“In an ideal world, Denuvo would die. As for me, I don’t know, time will tell,” he concludes.

Source: TF, for the latest info on copyright, file-sharing, torrent sites and more. We also have VPN discounts, offers and coupons

# Give Your WordPress Blog a Voice With Our New Amazon Polly Plugin

Post Syndicated from Jeff Barr original https://aws.amazon.com/blogs/aws/give-your-wordpress-blog-a-voice-with-our-new-amazon-polly-plugin/

I first told you about Polly in late 2016 in my post Amazon Polly – Text to Speech in 47 Voices and 24 Languages. After that AWS re:Invent launch, we added support for Korean, five new voices, and made Polly available in all Regions in the aws partition. We also added whispering, speech marks, a timbre effect, and dynamic range compression.

New WordPress Plugin
Today we are launching a WordPress plugin that uses Polly to create high-quality audio versions of your blog posts. You can access the audio from within the post or in podcast form using a feature that we call Amazon Pollycast! Both options make your content more accessible and can help you to reach a wider audience. This plugin was a joint effort between the AWS team our friends at AWS Advanced Technology Partner WP Engine.

As you will see, the plugin is easy to install and configure. You can use it with installations of WordPress that you run on your own infrastructure or on AWS. Either way, you have access to all of Polly’s voices along with a wide variety of configuration options. The generated audio (an MP3 file for each post) can be stored alongside your WordPress content, or in Amazon Simple Storage Service (S3), with optional support for content distribution via Amazon CloudFront.

Installing the Plugin
I did not have an existing WordPress-powered blog, so I begin by launching a Lightsail instance using the WordPress 4.8.1 blueprint:

Then I follow these directions to access my login credentials:

Credentials in hand, I log in to the WordPress Dashboard:

The plugin makes calls to AWS, and needs to have credentials in order to do so. I hop over to the IAM Console and created a new policy. The policy allows the plugin to access a carefully selected set of S3 and Polly functions (find the full policy in the README):

Then I create an IAM user (wp-polly-user). I enter the name and indicate that it will be used for Programmatic Access:

Then I attach the policy that I just created, and click on Review:

I review my settings (not shown) and then click on Create User. Then I copy the two values (Access Key ID and Secret Access Key) into a secure location. Possession of these keys allows the bearer to make calls to AWS so I take care not to leave them lying around.

Now I am ready to install the plugin! I go back to the WordPress Dashboard and click on Add New in the Plugins menu:

Then I click on Upload Plugin and locate the ZIP file that I downloaded from the WordPress Plugins site. After I find it I click on Install Now to proceed:

WordPress uploads and installs the plugin. Now I click on Activate Plugin to move ahead:

With the plugin installed, I click on Settings to set it up:

I enter my keys and click on Save Changes:

The General settings let me control the sample rate, voice, player position, the default setting for new posts, and the autoplay option. I can leave all of the settings as-is to get started:

The Cloud Storage settings let me store audio in S3 and to use CloudFront to distribute the audio:

The Amazon Pollycast settings give me control over the iTunes parameters that are included in the generated RSS feed:

Finally, the Bulk Update button lets me regenerate all of the audio files after I change any of the other settings:

With the plugin installed and configured, I can create a new post. As you can see, the plugin can be enabled and customized for each post:

I can see how much it will cost to convert to audio with a click:

When I click on Publish, the plugin breaks the text into multiple blocks on sentence boundaries, calls the Polly SynthesizeSpeech API for each block, and accumulates the resulting audio in a single MP3 file. The published blog post references the file using the <audio> tag. Here’s the post:

I can’t seem to use an <audio> tag in this post, but you can download and play the MP3 file yourself if you’d like.

The Pollycast feature generates an RSS file with links to an MP3 file for each post:

Pricing
The plugin will make calls to Amazon Polly each time the post is saved or updated. Pricing is based on the number of characters in the speech requests, as described on the Polly Pricing page. Also, the AWS Free Tier lets you process up to 5 million characters per month at no charge, for a period of one year that starts when you make your first call to Polly.

Going Further
The plugin is available on GitHub in source code form and we are looking forward to your pull requests! Here are a couple of ideas to get you started:

Voice Per Author – Allow selection of a distinct Polly voice for each author.

Quoted Text – For blogs that make frequent use of embedded quotes, use a distinct voice for the quotes.

Translation – Use Amazon Translate to translate the texts into another language, and then use Polly to generate audio in that language.

Other Blogging Engines – Build a similar plugin for your favorite blogging engine.

SSML Support – Figure out an interesting way to use Polly’s SSML tags to add additional character to the audio.

Let me know what you come up with!

Jeff;

# Free Electrons becomes Bootlin

Post Syndicated from jake original https://lwn.net/Articles/746345/rss

Longtime embedded Linux development company Free Electrons has just changed its name to Bootlin due to a trademark dispute (with “FREE SAS, a French telecom operator, known as the owner of the free.fr website“). It is possible that Free Electrons may lose access to its “free-electrons.com” domain name as part of the dispute, so links to the many resources that Free Electrons hosts (including documentation and conference videos) should be updated to use “bootlin.com”. “The services we offer are different, we target a different audience (professionals instead of individuals), and most of our communication efforts are in English, to reach an international audience. Therefore Michael Opdenacker and Free Electrons’ management believe that there is no risk of confusion between Free Electrons and FREE SAS.

However, FREE SAS has filed in excess of 100 oppositions and District Court actions against trademarks or name containing “free”. In view of the resources needed to fight this case, Free Electrons has decided to change name without waiting for the decision of the District Court.

This will allow us to stay focused on our projects rather than exhausting ourselves fighting a long legal battle.”

# Addressing Data Residency with AWS

Post Syndicated from Min Hyun original https://aws.amazon.com/blogs/security/addressing-data-residency-with-aws/

AWS has released a new whitepaper that has been requested by many AWS customers: AWS Policy Perspectives: Data Residency. Data residency is the requirement that all customer content processed and stored in an IT system must remain within a specific country’s borders, and it is one of the foremost concerns of governments that want to use commercial cloud services. General cybersecurity concerns and concerns about government requests for data have contributed to a continued focus on keeping data within countries’ borders. In fact, some governments have determined that mandating data residency provides an extra layer of security.

This approach, however, is counterproductive to the data protection objectives and the IT modernization and global economic growth goals that many governments have set as milestones. This new whitepaper addresses the real and perceived security risks expressed by governments when they demand in-country data residency by identifying the most likely and prevalent IT vulnerabilities and security risks, explaining the native security embedded in cloud services, and highlighting the roles and responsibilities of cloud service providers (CSPs), governments, and customers in protecting data.

Large-scale, multinational CSPs, often called hyperscale CSPs, represent a transformational disruption in technology because of how they support their customers with high degrees of efficiency, agility, and innovation as part of world-class security offerings. The whitepaper explains how hyperscale CSPs, such as AWS, that might be located out of country provide their customers the ability to achieve high levels of data protection through safeguards on their own platform and with turnkey tooling for their customers. They do this while at the same time preserving nation-state regulatory sovereignty.

The whitepaper also considers the commercial, public-sector, and economic effects of data residency policies and offers considerations for governments to evaluate before enforcing requirements that can unintentionally limit public-sector digital transformation goals, in turn possibly leading to increased cybersecurity risk.

AWS continues to engage with governments around the world to hear and address their top-of-mind security concerns. We take seriously our commitment to advocate for our customers’ interests and enforce security from “ground zero.” This means that when customers use AWS, they can have the confidence that their data is protected with a level of assurance that meets, if not exceeds, their needs, regardless of where the data resides.

– Min Hyun, Cloud Security Policy Strategist

# Yaghmour: Ten Days in Shenzhen

Post Syndicated from jake original https://lwn.net/Articles/745708/rss

On his blog, embedded developer Karim Yaghmour has written about his ten-day trip to Shenzen, China, which is known as the “Silicon Valley of hardware”. His lengthy trip report covers much that would be of use to others who are thinking of making the trip, but also serves as an interesting travelogue even for those who are likely to never go. “The map didn’t disappoint and I was able to find a large number of kiosks selling some of the items I was interested in. Obviously many kiosks also had items that I had seen on Amazon or elsewhere as well. I was mostly focusing on things I hadn’t seen before. After a few hours of walking floors upon floors of shops, I was ready to start focusing on other aspects of my research: hard to source and/or evaluate components, tools and expanding my knowledge of what was available in the hardware space. Hint: TEGES’ [The Essential Guide to Electronics in Shenzhen] advice about having comfortable shoes and comfortable clothing is completely warranted.

Finding tools was relatively easy. TEGES indicates the building and floor to go to, and you’ll find most anything you can think of from rework stations, to pick-and-place machines, and including things like oscilloscopes, stereo microscopes, multimeters, screwdrivers, etc. In the process I saw some tools which I couldn’t immediately figure out the purpose for, but later found out their uses on some other visits. Satisfied with a first glance at the tools, I set out to look for one specific component I was having a hard time with. That proved a lot more difficult than anticipated. Actually I should qualify that. It was trivial to find tons of it, just not something that matched exactly what I needed. I used TEGES to identify one part of the market that seemed most likely to have what I was looking for, but again, I could find lots of it, just not what I needed.”

# SUPER game night 3: GAMES MADE QUICK??? 2.0

Post Syndicated from Eevee original https://eev.ee/blog/2018/01/23/super-game-night-3-games-made-quick-2-0/

Game night continues with a smorgasbord of games from my recent game jam, GAMES MADE QUICK??? 2.0!

The idea was to make a game in only a week while watching AGDQ, as an alternative to doing absolutely nothing for a week while watching AGDQ. (I didn’t submit a game myself; I was chugging along on my Anise game, which isn’t finished yet.)

I can’t very well run a game jam and not play any of the games, so here’s some of them in no particular order! Enjoy!

These are impressions, not reviews. I try to avoid major/ending spoilers, but big plot points do tend to leave impressions.

## Weather Quest, by timlmul

short · rpg · jan 2017 · (lin)/mac/win · free on itch · jam entry

Weather Quest is its author’s first shipped game, written completely from scratch (the only vendored code is a micro OO base). It’s very short, but as someone who has also written LÖVE games completely from scratch, I can attest that producing something this game-like in a week is a fucking miracle. Bravo!

For reference, a week into my first foray, I think I was probably still writing my own Tiled importer like an idiot.

Only Mac and Windows builds are on itch, but it’s a LÖVE game, so Linux folks can just grab a zip from GitHub and throw that at love.

FINAL SCORE: ⛅☔☀

## Pancake Numbers Simulator, by AnorakThePrimordial

short · sim · jan 2017 · lin/mac/win · free on itch · jam entry

Given a stack of N pancakes (of all different sizes and in no particular order), the Nth pancake number is the most flips you could possibly need to sort the pancakes in order with the smallest on top. A “flip” is sticking a spatula under one of the pancakes and flipping the whole sub-stack over. There’s, ah, a video embedded on the game page with some visuals.

Anyway, this game lets you simulate sorting a stack via pancake flipping, which is surprisingly satisfying! I enjoy cleaning up little simulated messes, such as… incorrectly-sorted pancakes, I guess?

This probably doesn’t work too well as a simulator for solving the general problem — you’d have to find an optimal solution for every permutation of N pancakes to be sure you were right. But it’s a nice interactive illustration of the problem, and if you know the pancake number for your stack size of choice (which I wish the game told you — for seven pancakes, it’s 8), then trying to restore a stack in that many moves makes for a nice quick puzzle.

FINAL SCORE: $$\frac{18}{11}$$

## Framed Animals, by chridd

short · metroidvania · jan 2017 · web/win · free on itch · jam entry

The concept here was to kill the frames, save the animals, which is a delightfully literal riff on a long-running AGDQ/SGDQ donation incentive — people vote with their dollars to decide whether Super Metroid speedrunners go out of their way to free the critters who show you how to walljump and shinespark. Super Metroid didn’t have a showing at this year’s AGDQ, and so we have this game instead.

It’s rough, but clever, and I got really into it pretty quickly — each animal you save gives you a new ability (in true Metroid style), and you get to test that ability out by playing as the animal, with only that ability and no others, to get yourself back to the most recent save point.

I did, tragically, manage to get myself stuck near what I think was about to be the end of the game, so some of the animals will remain framed forever. What an unsatisfying conclusion.

Gravity feels a little high given the size of the screen, and like most tile-less platformers, there’s not really any way to gauge how high or long your jump is before you leap. But I’m only even nitpicking because I think this is a great idea and I hope the author really does keep working on it.

FINAL SCORE: 136,596.69 ## Battle 4 Glory, by Storyteller Games short · fighter · jan 2017 · win · free on itch · jam entry This is a Smash Bros-style brawler, complete with the four players, the 2D play area in a 3D world, and the random stage obstacles showing up. I do like the Smash style, despite not otherwise being a fan of fighting games, so it’s nice to see another game chase that aesthetic. Alas, that’s about as far as it got — which is pretty far for a week of work! I don’t know what more to say, though. The environments are neat, but unless I’m missing something, the only actions at your disposal are jumping and very weak melee attacks. I did have a good few minutes of fun fruitlessly mashing myself against the bumbling bots, as you can see. FINAL SCORE: 300% ## Icnaluferu Guild, Year Sixteen, by CHz short · adventure · jan 2017 · web · free on itch · jam entry Here we have the first of several games made with bitsy, a micro game making tool that basically only supports walking around, talking to people, and picking up items. I tell you this because I think half of my appreciation for this game is in the ways it wriggled against those limits to emulate a Zelda-like dungeon crawler. Everything in here is totally fake, and you can’t really understand just how fake unless you’ve tried to make something complicated with bitsy. It’s pretty good. The dialogue is entertaining (the rest of your party develops distinct personalities solely through oneliners, somehow), the riffs on standard dungeon fare are charming, and the Link’s Awakening-esque perspective walls around the edges of each room are fucking glorious. FINAL SCORE: 2 bits ## The Lonely Tapes, by JTHomeslice short · rpg · jan 2017 · web · free on itch · jam entry Another bitsy entry, this one sees you play as a Wal— sorry, a JogDawg, which has lost its cassette tapes and needs to go recover them! (A cassette tape is like a VHS, but for music.) (A VHS is—) I have the sneaking suspicion that I missed out on some musical in-jokes, due to being uncultured swine. I still enjoyed the game — it’s always clear when someone is passionate about the thing they’re writing about, and I could tell I was awash in that aura even if some of it went over my head. You know you’ve done good if someone from way outside your sphere shows up and still has a good time. FINAL SCORE: Nine… Inch Nails? They’re a band, right? God I don’t know write your own damn joke ## Pirate Kitty-Quest, by TheKoolestKid short · adventure · jan 2017 · win · free on itch · jam entry I completely forgot I’d even given “my birthday” and “my cat” as mostly-joking jam themes until I stumbled upon this incredible gem. I don’t think — let me just check here and — yeah no this person doesn’t even follow me on Twitter. I have no idea who they are? BUT THEY MADE A GAME ABOUT ANISE AS A PIRATE, LOOKING FOR TREASURE PIRATE. ANISE PIRATE ANISE!!! This game wins the jam, hands down. 🏆 FINAL SCORE: Yarr, eight pieces o’ eight ## CHIPS Mario, by NovaSquirrel short · platformer · jan 2017 · (lin/mac)/win · free on itch · jam entry You see this? This is fucking witchcraft. This game is made with MegaZeux. MegaZeux games look like THIS. Text-mode, bound to a grid, with two colors per cell. That’s all you get. Until now, apparently?? The game is a tech demo of “unbound” sprites, which can be drawn on top of the character grid without being aligned to it. And apparently have looser color restrictions. The collision is a little glitchy, which isn’t surprising for a MegaZeux platformer; I had some fun interactions with platforms a couple times. But hey, goddamn, it’s free-moving Mario, in MegaZeux, what the hell. (I’m looking at the most recently added games on DigitalMZX now, and I notice that not only is this game in the first slot, but NovaSquirrel’s MegaZeux entry for Strawberry Jam last February is still in the seventh slot. RIP, MegaZeux. I’m surprised a major feature like this was even added if the community has largely evaporated?) FINAL SCORE: n/a, disqualified for being probably summoned from the depths of Hell ## d!¢< pic, by 573 Games short · story · jan 2017 · web · free on itch · jam entry This is a short story about not sending dick pics. It’s very short, so I can’t say much without spoiling it, but: you are generally prompted to either text something reasonable, or send a dick pic. You should not send a dick pic. It’s a fascinating artifact, not because of the work itself, but because it’s so terse that I genuinely can’t tell what the author was even going for. And this is the kind of subject where the author was, surely, going for something. Right? But was it genuinely intended to be educational, or was it tongue-in-cheek about how some dudes still don’t get it? Or is it side-eying the player who clicks the obviously wrong option just for kicks, which is the same reason people do it for real? Or is it commentary on how “send a dick pic” is a literal option for every response in a real conversation, too, and it’s not that hard to just not do it — unless you are one of the kinds of people who just feels a compulsion to try everything, anything, just because you can? Or is it just a quick Twine and I am way too deep in this? God, just play the thing, it’s shorter than this paragraph. I’m also left wondering when it is appropriate to send a dick pic. Presumably there is a correct time? Hopefully the author will enter Strawberry Jam 2 to expound upon this. FINAL SCORE: 3½” 😉 ## Marble maze, by Shtille short · arcade · jan 2017 · win · free on itch · jam entry Ah, hm. So this is a maze navigated by rolling a marble around. You use WASD to move the marble, and you can also turn the camera with the arrow keys. The trouble is… the marble’s movement is always relative to the world, not the camera. That means if you turn the camera 30° and then try to move the marble, it’ll move at a 30° angle from your point of view. That makes navigating a maze, er, difficult. Camera-relative movement is the kind of thing I take so much for granted that I wouldn’t even think to do otherwise, and I think it’s valuable to look at surprising choices that violate fundamental conventions, so I’m trying to take this as a nudge out of my comfort zone. What could you design in an interesting way that used world-relative movement? Probably not the player, but maybe something else in the world, as long as you had strong landmarks? Hmm. FINAL SCORE: ᘔ ## Refactor: flight, by fluffy short · arcade · jan 2017 · lin/mac/win · free on itch · jam entry Refactor is a game album, which is rather a lot what it sounds like, and Flight is one of the tracks. Which makes this a single, I suppose. It’s one of those games where you move down an oddly-shaped tunnel trying not to hit the walls, but with some cute twists. Coins and gems hop up from the bottom of the screen in time with the music, and collecting them gives you points. Hitting a wall costs you some points and kills your momentum, but I don’t think outright losing is possible, which is great for me! Also, the monk cycles through several animal faces. I don’t know why, and it’s very good. One of those odd but memorable details that sits squarely on the intersection of abstract, mysterious, and a bit weird, and refuses to budge from that spot. The music is great too? Really chill all around. FINAL SCORE: 🎵🎵🎵🎵 ## The Adventures of Klyde short · adventure · jan 2017 · web · free on itch · jam entry Another bitsy game, this one starring a pig (humorously symbolized by a giant pig nose with ears) who must collect fruit and solve some puzzles. This is charmingly nostalgic for me — it reminds me of some standard fare in engines like MegaZeux, where the obvious things to do when presented with tiles and pickups were to make mazes. I don’t mean that in a bad way; the maze is the fundamental environmental obstacle. A couple places in here felt like invisible teleport mazes I had to brute-force, but I might have been missing a hint somewhere. I did make it through with only a little trouble, but alas — I stepped in a bad warp somewhere and got sent to the upper left corner of the starting screen, which is surrounded by walls. So Klyde’s new life is being trapped eternally in a nowhere space. FINAL SCORE: 19/20 apples ## And more That was only a third of the games, and I don’t think even half of the ones I’ve played. I’ll have to do a second post covering the rest of them? Maybe a third? Or maybe this is a ludicrous format for commenting on several dozen games and I should try to narrow it down to the ones that resonated the most for Strawberry Jam 2? Maybe?? # [] BPFd: Running BCC tools remotely across systems and architectures

Post Syndicated from corbet original https://lwn.net/Articles/744522/rss

BPF is an increasingly capable tool for instrumenting and tracing the
operation of the kernel; it has enabled the creation of the growing set of
BCC tools. Unfortunately, BCC has no support for a cross-development
workflow where the development machine and the target machine running the
developed code are different. Cross-development is favored by
embedded-systems kernel developers who tend to develop on an x86 host and
then flash and test their code on SoCs (System on Chips) based on the ARM
architecture. In this article, I introduce BPFd, a project to enable cross
development using BPF and BCC.

# Create SLUG! It’s just like Snake, but with a slug

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/slug-snake/

Recreate Snake, the favourite mobile phone game from the late nineties, using a slug*, a Raspberry Pi, a Sense HAT, and our free resource!

*A virtual slug. Not a real slug. Please leave the real slugs out in nature.

## Snake SLUG!

Move aside, Angry Birds! On your bike, Pokémon Go! When it comes to the cream of the crop of mobile phone games, Snake holds the top spot.

I could while away the hours…

You may still have an old Nokia 3310 lost in the depths of a drawer somewhere — the drawer that won’t open all the way because something inside is jammed at an odd angle. So it will be far easier to grab your Pi and Sense HAT, or use the free Sense HAT emulator (online or on Raspbian), and code Snake SLUG yourself. In doing so, you can introduce the smaller residents of your household to the best reptile-focused game ever made…now with added mollusc.

## The resource

To try out the game for yourself, head to our resource page, where you’ll find the online Sense HAT emulator embedded and ready to roll.

It’ll look just like this, and you can use your computer’s arrow keys to direct your slug toward her tasty treats.

From there, you’ll be taken on a step-by-step journey from zero to SLUG glory while coding your own versionof the game in Python. On the way, you’ll learn to work with two-dimensional lists and to use the Sense HAT’s pixel display and joystick input. And by completing the resource, you’ll expand your understanding of applying abstraction and decomposition to solve more complex problems, in line with our Digital Making Curriculum.

## The Sense HAT

The Raspberry Pi Sense HAT was originally designed and made as part of the Astro Pi mission in December 2015. With an 8×8 RGB LED matrix, a joystick, and a plethora of on-board sensors including an accelerometer, gyroscope, and magnetometer, it’s a great add-on for your digital making toolkit, and excellent for projects involving data collection and evaluation.

You can find more of our free Sense HAT tutorials here, including for making Flappy Bird Astronaut, a marble maze, and Pong.

The post Create SLUG! It’s just like Snake, but with a slug appeared first on Raspberry Pi.

# Spectre and Meltdown Attacks Against Microprocessors

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2018/01/spectre_and_mel_1.html

The security of pretty much every computer on the planet has just gotten a lot worse, and the only real solution — which of course is not a solution — is to throw them all away and buy new ones.

On Wednesday, researchers just announced a series of major security vulnerabilities in the microprocessors at the heart of the world’s computers for the past 15-20 years. They’ve been named Spectre and Meltdown, and they have to do with manipulating different ways processors optimize performance by rearranging the order of instructions or performing different instructions in parallel. An attacker who controls one process on a system can use the vulnerabilities to steal secrets elsewhere on the computer. (The research papers are here and here.)

This means that a malicious app on your phone could steal data from your other apps. Or a malicious program on your computer — maybe one running in a browser window from that sketchy site you’re visiting, or as a result of a phishing attack — can steal data elsewhere on your machine. Cloud services, which often share machines amongst several customers, are especially vulnerable. This affects corporate applications running on cloud infrastructure, and end-user cloud applications like Google Drive. Someone can run a process in the cloud and steal data from every other users on the same hardware.

Information about these flaws has been secretly circulating amongst the major IT companies for months as they researched the ramifications and coordinated updates. The details were supposed to be released next week, but the story broke early and everyone is scrambling. By now all the major cloud vendors have patched their systems against the vulnerabilities that can be patched against.

“Throw it away and buy a new one” is ridiculous security advice, but it’s what US-CERT recommends. It is also unworkable. The problem is that there isn’t anything to buy that isn’t vulnerable. Pretty much every major processor made in the past 20 years is vulnerable to some flavor of these vulnerabilities. Patching against Meltdown can degrade performance by almost a third. And there’s no patch for Spectre; the microprocessors have to be redesigned to prevent the attack, and that will take years. (Here’s a running list of who’s patched what.)

This is bad, but expect it more and more. Several trends are converging in a way that makes our current system of patching security vulnerabilities harder to implement.

The first is that these vulnerabilities affect embedded computers in consumer devices. Unlike our computer and phones, these systems are designed and produced at a lower profit margin with less engineering expertise. There aren’t security teams on call to write patches, and there often aren’t mechanisms to push patches onto the devices. We’re already seeing this with home routers, digital video recorders, and webcams. The vulnerability that allowed them to be taken over by the Mirai botnet last August simply can’t be fixed.

The second is that some of the patches require updating the computer’s firmware. This is much harder to walk consumers through, and is more likely to permanently brick the device if something goes wrong. It also requires more coordination. In November, Intel released a firmware update to fix a vulnerability in its Management Engine (ME): another flaw in its microprocessors. But it couldn’t get that update directly to users; it had to work with the individual hardware companies, and some of them just weren’t capable of getting the update to their customers.

We’re already seeing this. Some patches require users to disable the computer’s password, which means organizations can’t automate the patch. Some antivirus software blocks the patch, or — worse — crashes the computer. This results in a three-step process: patch your antivirus software, patch your operating system, and then patch the computer’s firmware.

The final reason is the nature of these vulnerabilities themselves. These aren’t normal software vulnerabilities, where a patch fixes the problem and everyone can move on. These vulnerabilities are in the fundamentals of how the microprocessor operates.

It shouldn’t be surprising that microprocessor designers have been building insecure hardware for 20 years. What’s surprising is that it took 20 years to discover it. In their rush to make computers faster, they weren’t thinking about security. They didn’t have the expertise to find these vulnerabilities. And those who did were too busy finding normal software vulnerabilities to examine microprocessors. Security researchers are starting to look more closely at these systems, so expect to hear about more vulnerabilities along these lines.

Spectre and Meltdown are pretty catastrophic vulnerabilities, but they only affect the confidentiality of data. Now that they — and the research into the Intel ME vulnerability — have shown researchers where to look, more is coming — and what they’ll find will be worse than either Spectre or Meltdown. There will be vulnerabilities that will allow attackers to manipulate or delete data across processes, potentially fatal in the computers controlling our cars or implanted medical devices. These will be similarly impossible to fix, and the only strategy will be to throw our devices away and buy new ones.

This isn’t to say you should immediately turn your computers and phones off and not use them for a few years. For the average user, this is just another attack method amongst many. All the major vendors are working on patches and workarounds for the attacks they can mitigate. All the normal security advice still applies: watch for phishing attacks, don’t click on strange e-mail attachments, don’t visit sketchy websites that might run malware on your browser, patch your systems regularly, and generally be careful on the Internet.

You probably won’t notice that performance hit once Meltdown is patched, except maybe in backup programs and networking applications. Embedded systems that do only one task, like your programmable thermostat or the computer in your refrigerator, are unaffected. Small microprocessors that don’t do all of the vulnerable fancy performance tricks are unaffected. Browsers will figure out how to mitigate this in software. Overall, the security of the average Internet-of-Things device is so bad that this attack is in the noise compared to the previously known risks.

It’s a much bigger problem for cloud vendors; the performance hit will be expensive, but I expect that they’ll figure out some clever way of detecting and blocking the attacks. All in all, as bad as Spectre and Meltdown are, I think we got lucky.

But more are coming, and they’ll be worse. 2018 will be the year of microprocessor vulnerabilities, and it’s going to be a wild ride.

Note: A shorter version of this essay previously appeared on CNN.com. My previous blog post on this topic contains additional links.

# Acoustical Attacks against Hard Drives

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2017/12/acoustical_atta.html

Interesting destructive attack: “Acoustic Denial of Service Attacks on HDDs“:

Abstract: Among storage components, hard disk drives (HDDs) have become the most commonly-used type of non-volatile storage due to their recent technological advances, including, enhanced energy efficacy and significantly-improved areal density. Such advances in HDDs have made them an inevitable part of numerous computing systems, including, personal computers, closed-circuit television (CCTV) systems, medical bedside monitors, and automated teller machines (ATMs). Despite the widespread use of HDDs and their critical role in real-world systems, there exist only a few research studies on the security of HDDs. In particular, prior research studies have discussed how HDDs can potentially leak critical private information through acoustic or electromagnetic emanations. Borrowing theoretical principles from acoustics and mechanics, we propose a novel denial-of-service (DoS) attack against HDDs that exploits a physical phenomenon, known as acoustic resonance. We perform a comprehensive examination of physical characteristics of several HDDs and create acoustic signals that cause significant vibrations in HDDs internal components. We demonstrate that such vibrations can negatively influence the performance of HDDs embedded in real-world systems. We show the feasibility of the proposed attack in two real-world case studies, namely, personal computers and CCTVs.

# MQTT 5: Is it time to upgrade to MQTT 5 yet?

Post Syndicated from The HiveMQ Team original https://www.hivemq.com/blog/mqtt-5-time-to-upgrade-yet/

### Is it time to upgrade to MQTT 5 yet?

Welcome to this week’s blog post! After last week’s Introduction to MQTT 5, many readers wondered when the successor to MQTT 3.1.1 is ready for prime time and can be used in future and existing projects.

Before we try to answer the question in more detail, we’d love to hear your thoughts about upgrading to MQTT 5. We prepared a small survey below. Let us know how your MQTT 5 upgrading plans are!

#### The MQTT 5 OASIS Standard

As of late December 2017, the MQTT 5 specification is not available as an official “Committee Specification” yet. In other words: MQTT 5 is not available yet officially. The foundation for every implementation of the standard is, that the Technical Committee at OASIS officially releases the standard.

The good news: Although no official version of the standard is available yet, fundamental changes to the current state of the specification are not expected.
The Public Review phase of the “Committee Specification Draft 2” finished without any major comments or issues. We at HiveMQ expect the MQTT 5 standard to be released in very late December 2017 or January 2018.

#### Current state of client libraries

To start using MQTT 5, you need two participants: An MQTT 5 client library implementation in your programming language(s) of choice and an MQTT 5 broker implementation (like HiveMQ). If both components support the new standard, you are good to go and can use the new version in your projects.

When it comes to MQTT libraries, Eclipse Paho is the one-stop shop for MQTT clients in most programming languages. A recent Paho mailing list entry stated that Paho plans to release MQTT 5 client libraries end of June 2018 for the following programming languages:

• C (+ embedded C)
• Java
• Go
• C++

If you’re feeling adventurous, at least the Java Paho client has preliminary MQTT 5 support available. You can play around with the API and get a feel about the upcoming Paho version. Just build the library from source and test it, but be aware that this is not safe for production use.

There is also a very basic test broker implementation available at Eclipse Paho which can be used for playing around. This is of course only for very basic tests and does not support all MQTT 5 features yet. If you’re planning to write your own library, this may be a good tool to test your implementation against.

There are of other individual MQTT library projects which may be worth to check out. As of December 2017 most of these libraries don’t have an MQTT 5 roadmap published yet.

#### HiveMQ and MQTT 5

You can’t use the new version of the MQTT protocol only by having a client that is ready for MQTT 5. The counterpart, the MQTT broker, also needs to fully support the new protocol version. At the time of writing, no broker is MQTT 5 ready yet.

HiveMQ was the first broker to fully support version 3.1.1 of MQTT and of course here at HiveMQ we are committed to give our customers the advantage of the new features of version 5 of the protocol as soon as possible and viable.

We are going to provide an Early Access version of the upcoming HiveMQ generation with MQTT 5 support by May/June 2018. If you’re a library developer or want to go live with the new protocol version as soon as possible: The Early Access version is for you. Add yourself to the Early Access Notification List and we’ll notify you when the Early Access version is available.

We expect to release the upcoming HiveMQ generation in the third quarter of 2018 with full support of ALL MQTT 5 features at scale in an interoperable way with previous MQTT versions.

#### When is MQTT 5 ready for prime time?

MQTT is typically used in mission critical environments where it’s not acceptable that parts of the infrastructure, broker or client, are unreliable or have some rough edges. So it’s typically not advisable to be the very first to try out new things in a critical production environment.

Here at HiveMQ we expect that the first users will go live to production in late Q3 (September) 2018 and in the subsequent months. After the releases of the Paho library in June and the HiveMQ Early Access version, the adoption of MQTT 5 is expected to increase rapidly.

So, is MQTT 5 ready for prime time yet (as of December 2017)? No.

Will the new version of the protocol be suitable for production environments in the second half of 2018: Yes, definitely.

#### Upcoming topics in this series

We will continue this blog post series in January after the European Christmas Holidays. To kick-off the technical part of the series, we will take a look at the foundational changes of the MQTT protocol. And after that, we will release one blog post per week that will thoroughly review and inspect one new feature in detail together with best practices and fun trivia.

If you want us to send the next and all upcoming articles directly into your inbox, just use the newsletter subscribe form below.

P.S. Don’t forget to let us know if MQTT 5 is of interest for you by participating in this quick poll.

Have an awesome week,
The HiveMQ Team

# What is HAMR and How Does It Enable the High-Capacity Needs of the Future?

Post Syndicated from Andy Klein original https://www.backblaze.com/blog/hamr-hard-drives/

During Q4, Backblaze deployed 100 petabytes worth of Seagate hard drives to our data centers. The newly deployed Seagate 10 and 12 TB drives are doing well and will help us meet our near term storage needs, but we know we’re going to need more drives — with higher capacities. That’s why the success of new hard drive technologies like Heat-Assisted Magnetic Recording (HAMR) from Seagate are very relevant to us here at Backblaze and to the storage industry in general. In today’s guest post we are pleased to have Mark Re, CTO at Seagate, give us an insider’s look behind the hard drive curtain to tell us how Seagate engineers are developing the HAMR technology and making it market ready starting in late 2018.

## What is HAMR and How Does It Enable the High-Capacity Needs of the Future?

Guest Blog Post by Mark Re, Seagate Senior Vice President and Chief Technology Officer

Earlier this year Seagate announced plans to make the first hard drives using Heat-Assisted Magnetic Recording, or HAMR, available by the end of 2018 in pilot volumes. Even as today’s market has embraced 10TB+ drives, the need for 20TB+ drives remains imperative in the relative near term. HAMR is the Seagate research team’s next major advance in hard drive technology.

HAMR is a technology that over time will enable a big increase in the amount of data that can be stored on a disk. A small laser is attached to a recording head, designed to heat a tiny spot on the disk where the data will be written. This allows a smaller bit cell to be written as either a 0 or a 1. The smaller bit cell size enables more bits to be crammed into a given surface area — increasing the areal density of data, and increasing drive capacity.

It sounds almost simple, but the science and engineering expertise required, the research, experimentation, lab development and product development to perfect this technology has been enormous. Below is an overview of the HAMR technology and you can dig into the details in our technical brief that provides a point-by-point rundown describing several key advances enabling the HAMR design.

As much time and resources as have been committed to developing HAMR, the need for its increased data density is indisputable. Demand for data storage keeps increasing. Businesses’ ability to manage and leverage more capacity is a competitive necessity, and IT spending on capacity continues to increase.

### History of Increasing Storage Capacity

For the last 50 years areal density in the hard disk drive has been growing faster than Moore’s law, which is a very good thing. After all, customers from data centers and cloud service providers to creative professionals and game enthusiasts rarely go shopping looking for a hard drive just like the one they bought two years ago. The demands of increasing data on storage capacities inevitably increase, thus the technology constantly evolves.

According to the Advanced Storage Technology Consortium, HAMR will be the next significant storage technology innovation to increase the amount of storage in the area available to store data, also called the disk’s “areal density.” We believe this boost in areal density will help fuel hard drive product development and growth through the next decade.

### Why do we Need to Develop Higher-Capacity Hard Drives? Can’t Current Technologies do the Job?

Why is HAMR’s increased data density so important?

Data has become critical to all aspects of human life, changing how we’re educated and entertained. It affects and informs the ways we experience each other and interact with businesses and the wider world. IDC research shows the datasphere — all the data generated by the world’s businesses and billions of consumer endpoints — will continue to double in size every two years. IDC forecasts that by 2025 the global datasphere will grow to 163 zettabytes (that is a trillion gigabytes). That’s ten times the 16.1 ZB of data generated in 2016. IDC cites five key trends intensifying the role of data in changing our world: embedded systems and the Internet of Things (IoT), instantly available mobile and real-time data, cognitive artificial intelligence (AI) systems, increased security data requirements, and critically, the evolution of data from playing a business background to playing a life-critical role.

Consumers use the cloud to manage everything from family photos and videos to data about their health and exercise routines. Real-time data created by connected devices — everything from Fitbit, Alexa and smart phones to home security systems, solar systems and autonomous cars — are fueling the emerging Data Age. On top of the obvious business and consumer data growth, our critical infrastructure like power grids, water systems, hospitals, road infrastructure and public transportation all demand and add to the growth of real-time data. Data is now a vital element in the smooth operation of all aspects of daily life.

All of this entails a significant infrastructure cost behind the scenes with the insatiable, global appetite for data storage. While a variety of storage technologies will continue to advance in data density (Seagate announced the first 60TB 3.5-inch SSD unit for example), high-capacity hard drives serve as the primary foundational core of our interconnected, cloud and IoT-based dependence on data.

## HAMR Hard Drive Technology

Seagate has been working on heat assisted magnetic recording (HAMR) in one form or another since the late 1990s. During this time we’ve made many breakthroughs in making reliable near field transducers, special high capacity HAMR media, and figuring out a way to put a laser on each and every head that is no larger than a grain of salt.

The development of HAMR has required Seagate to consider and overcome a myriad of scientific and technical challenges including new kinds of magnetic media, nano-plasmonic device design and fabrication, laser integration, high-temperature head-disk interactions, and thermal regulation.

A typical hard drive inside any computer or server contains one or more rigid disks coated with a magnetically sensitive film consisting of tiny magnetic grains. Data is recorded when a magnetic write-head flies just above the spinning disk; the write head rapidly flips the magnetization of one magnetic region of grains so that its magnetic pole points up or down, to encode a 1 or a 0 in binary code.

Increasing the amount of data you can store on a disk requires cramming magnetic regions closer together, which means the grains need to be smaller so they won’t interfere with each other.

Heat Assisted Magnetic Recording (HAMR) is the next step to enable us to increase the density of grains — or bit density. Current projections are that HAMR can achieve 5 Tbpsi (Terabits per square inch) on conventional HAMR media, and in the future will be able to achieve 10 Tbpsi or higher with bit patterned media (in which discrete dots are predefined on the media in regular, efficient, very dense patterns). These technologies will enable hard drives with capacities higher than 100 TB before 2030.

The major problem with packing bits so closely together is that if you do that on conventional magnetic media, the bits (and the data they represent) become thermally unstable, and may flip. So, to make the grains maintain their stability — their ability to store bits over a long period of time — we need to develop a recording media that has higher coercivity. That means it’s magnetically more stable during storage, but it is more difficult to change the magnetic characteristics of the media when writing (harder to flip a grain from a 0 to a 1 or vice versa).

That’s why HAMR’s first key hardware advance required developing a new recording media that keeps bits stable — using high anisotropy (or “hard”) magnetic materials such as iron-platinum alloy (FePt), which resist magnetic change at normal temperatures. Over years of HAMR development, Seagate researchers have tested and proven out a variety of FePt granular media films, with varying alloy composition and chemical ordering.

In fact the new media is so “hard” that conventional recording heads won’t be able to flip the bits, or write new data, under normal temperatures. If you add heat to the tiny spot on which you want to write data, you can make the media’s coercive field lower than the magnetic field provided by the recording head — in other words, enable the write head to flip that bit.

So, a challenge with HAMR has been to replace conventional perpendicular magnetic recording (PMR), in which the write head operates at room temperature, with a write technology that heats the thin film recording medium on the disk platter to temperatures above 400 °C. The basic principle is to heat a tiny region of several magnetic grains for a very short time (~1 nanoseconds) to a temperature high enough to make the media’s coercive field lower than the write head’s magnetic field. Immediately after the heat pulse, the region quickly cools down and the bit’s magnetic orientation is frozen in place.

Applying this dynamic nano-heating is where HAMR’s famous “laser” comes in. A plasmonic near-field transducer (NFT) has been integrated into the recording head, to heat the media and enable magnetic change at a specific point. Plasmonic NFTs are used to focus and confine light energy to regions smaller than the wavelength of light. This enables us to heat an extremely small region, measured in nanometers, on the disk media to reduce its magnetic coercivity,

### Moving HAMR Forward

As always in advanced engineering, the devil — or many devils — is in the details. As noted earlier, our technical brief provides a point-by-point short illustrated summary of HAMR’s key changes.

Although hard work remains, we believe this technology is nearly ready for commercialization. Seagate has the best engineers in the world working towards a goal of a 20 Terabyte drive by 2019. We hope we’ve given you a glimpse into the amount of engineering that goes into a hard drive. Keeping up with the world’s insatiable appetite to create, capture, store, secure, manage, analyze, rapidly access and share data is a challenge we work on every day.

With thousands of HAMR drives already being made in our manufacturing facilities, our internal and external supply chain is solidly in place, and volume manufacturing tools are online. This year we began shipping initial units for customer tests, and production units will ship to key customers by the end of 2018. Prepare for breakthrough capacities.

# Announcing FreeRTOS Kernel Version 10 (AWS Open Source Blog)

Post Syndicated from jake original https://lwn.net/Articles/740372/rss

Amazon has announced the release of FreeRTOS kernel version 10, with a new license: “FreeRTOS was created in 2003 by Richard Barry. It rapidly became popular, consistently ranking very high in EETimes surveys on embedded operating systems. After 15 years of maintaining this critical piece of software infrastructure with very limited human resources, last year Richard joined Amazon.

Today we are releasing the core open source code as FreeRTOS kernel version 10, now under the MIT license (instead of its previous modified GPLv2 license). Simplified licensing has long been requested by the FreeRTOS community. The specific choice of the MIT license was based on the needs of the embedded systems community: the MIT license is commonly used in open hardware projects, and is generally whitelisted for enterprise use.” While the modified GPLv2 was removed, it was replaced with a slightly modified MIT license that adds: “If you wish to use our Amazon FreeRTOS name, please do so in a
fair use way that does not cause confusion.
” There is concern that change makes it a different license; the Open Source Initiative and Amazon open-source folks are working on clarifying that.

# Object models

Post Syndicated from Eevee original https://eev.ee/blog/2017/11/28/object-models/

Anonymous asks, with dollars:

More about programming languages!

Well then!

I’ve written before about what I think objects are: state and behavior, which in practice mostly means method calls.

I suspect that the popular impression of what objects are, and also how they should work, comes from whatever C++ and Java happen to do. From that point of view, the whole post above is probably nonsense. If the baseline notion of “object” is a rigid definition woven tightly into the design of two massively popular languages, then it doesn’t even make sense to talk about what “object” should mean — it does mean the features of those languages, and cannot possibly mean anything else.

I think that’s a shame! It piles a lot of baggage onto a fairly simple idea. Polymorphism, for example, has nothing to do with objects — it’s an escape hatch for static type systems. Inheritance isn’t the only way to reuse code between objects, but it’s the easiest and fastest one, so it’s what we get. Frankly, it’s much closer to a speed tradeoff than a fundamental part of the concept.

We could do with more experimentation around how objects work, but that’s impossible in the languages most commonly thought of as object-oriented.

Here, then, is a (very) brief run through the inner workings of objects in four very dynamic languages. I don’t think I really appreciated objects until I’d spent some time with Python, and I hope this can help someone else whet their own appetite.

## Python 3

Of the four languages I’m going to touch on, Python will look the most familiar to the Java and C++ crowd. For starters, it actually has a class construct.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 class Vector: def __init__(self, x, y): self.x = x self.y = y def __neg__(self): return Vector(-self.x, -self.y) def __div__(self, denom): return Vector(self.x / denom, self.y / denom) @property def magnitude(self): return (self.x ** 2 + self.y ** 2) ** 0.5 def normalized(self): return self / self.magnitude 

The __init__ method is an initializer, which is like a constructor but named differently (because the object already exists in a usable form by the time the initializer is called). Operator overloading is done by implementing methods with other special __dunder__ names. Properties can be created with @property, where the @ is syntax for applying a wrapper function to a function as it’s defined. You can do inheritance, even multiply:

 1 2 3 4 class Foo(A, B, C): def bar(self, x, y, z): # do some stuff super().bar(x, y, z) 

Cool, a very traditional object model.

Except… for some details.

### Some details

For one, Python objects don’t have a fixed layout. Code both inside and outside the class can add or remove whatever attributes they want from whatever object they want. The underlying storage is just a dict, Python’s mapping type. (Or, rather, something like one. Also, it’s possible to change, which will probably be the case for everything I say here.)

If you create some attributes at the class level, you’ll start to get a peek behind the curtains:

  1 2 3 4 5 6 7 8 9 10 11 12 class Foo: values = [] def add_value(self, value): self.values.append(value) a = Foo() b = Foo() a.add_value('a') print(a.values) # ['a'] b.add_value('b') print(b.values) # ['a', 'b'] 

The [] assigned to values isn’t a default assigned to each object. In fact, the individual objects don’t know about it at all! You can use vars(a) to get at the underlying storage dict, and you won’t see a values entry in there anywhere.

Instead, values lives on the class, which is a value (and thus an object) in its own right. When Python is asked for self.values, it checks to see if self has a values attribute; in this case, it doesn’t, so Python keeps going and asks the class for one.

Python’s object model is secretly prototypical — a class acts as a prototype, as a shared set of fallback values, for its objects.

In fact, this is also how method calls work! They aren’t syntactically special at all, which you can see by separating the attribute lookup from the call.

 1 2 3 print("abc".startswith("a")) # True meth = "abc".startswith print(meth("a")) # True 

Reading obj.method looks for a method attribute; if there isn’t one on obj, Python checks the class. Here, it finds one: it’s a function from the class body.

Ah, but wait! In the code I just showed, meth seems to “know” the object it came from, so it can’t just be a plain function. If you inspect the resulting value, it claims to be a “bound method” or “built-in method” rather than a function, too. Something funny is going on here, and that funny something is the descriptor protocol.

### Descriptors

Python allows attributes to implement their own custom behavior when read from or written to. Such an attribute is called a descriptor. I’ve written about them before, but here’s a quick overview.

If Python looks up an attribute, finds it in a class, and the value it gets has a __get__ method… then instead of using that value, Python will use the return value of its __get__ method.

The @property decorator works this way. The magnitude property in my original example was shorthand for doing this:

  1 2 3 4 5 6 7 8 9 10 11 12 class MagnitudeDescriptor: def __get__(self, instance, owner): if instance is None: return self return (instance.x ** 2 + instance.y ** 2) ** 0.5 class Vector: def __init__(self, x, y): self.x = x self.y = y magnitude = MagnitudeDescriptor() 

When you ask for somevec.magnitude, Python checks somevec but doesn’t find magnitude, so it consults the class instead. The class does have a magnitude, and it’s a value with a __get__ method, so Python calls that method and somevec.magnitude evaluates to its return value. (The instance is None check is because __get__ is called even if you get the descriptor directly from the class via Vector.magnitude. A descriptor intended to work on instances can’t do anything useful in that case, so the convention is to return the descriptor itself.)

You can also intercept attempts to write to or delete an attribute, and do absolutely whatever you want instead. But note that, similar to operating overloading in Python, the descriptor must be on a class; you can’t just slap one on an arbitrary object and have it work.

This brings me right around to how “bound methods” actually work. Functions are descriptors! The function type implements __get__, and when a function is retrieved from a class via an instance, that __get__ bundles the function and the instance together into a tiny bound method object. It’s essentially:

 1 2 3 4 5 class FunctionType: def __get__(self, instance, owner): if instance is None: return self return functools.partial(self, instance) 

The self passed as the first argument to methods is not special or magical in any way. It’s built out of a few simple pieces that are also readily accessible to Python code.

Note also that because obj.method() is just an attribute lookup and a call, Python doesn’t actually care whether method is a method on the class or just some callable thing on the object. You won’t get the auto-self behavior if it’s on the object, but otherwise there’s no difference.

### More attribute access, and the interesting part

Descriptors are one of several ways to customize attribute access. Classes can implement __getattr__ to intervene when an attribute isn’t found on an object; __setattr__ and __delattr__ to intervene when any attribute is set or deleted; and __getattribute__ to implement unconditional attribute access. (That last one is a fantastic way to create accidental recursion, since any attribute access you do within __getattribute__ will of course call __getattribute__ again.)

Here’s what I really love about Python. It might seem like a magical special case that descriptors only work on classes, but it really isn’t. You could implement exactly the same behavior yourself, in pure Python, using only the things I’ve just told you about. Classes are themselves objects, remember, and they are instances of type, so the reason descriptors only work on classes is that type effectively does this:

  1 2 3 4 5 6 7 8 9 10 class type: def __getattribute__(self, name): value = super().__getattribute__(name) # like all op overloads, __get__ must be on the type, not the instance ty = type(value) if hasattr(ty, '__get__'): # it's a descriptor! this is a class access so there is no instance return ty.__get__(value, None, self) else: return value 

You can even trivially prove to yourself that this is what’s going on by skipping over types behavior:

  1 2 3 4 5 6 7 8 9 10 class Descriptor: def __get__(self, instance, owner): print('called!') class Foo: bar = Descriptor() Foo.bar # called! type.__getattribute__(Foo, 'bar') # called! object.__getattribute__(Foo, 'bar') # ... 

And that’s not all! The mysterious super function, used to exhaustively traverse superclass method calls even in the face of diamond inheritance, can also be expressed in pure Python using these primitives. You could write your own superclass calling convention and use it exactly the same way as super.

This is one of the things I really like about Python. Very little of it is truly magical; virtually everything about the object model exists in the types rather than the language, which means virtually everything can be customized in pure Python.

### Class creation and metaclasses

A very brief word on all of this stuff, since I could talk forever about Python and I have three other languages to get to.

The class block itself is fairly interesting. It looks like this:

 1 2 class Name(*bases, **kwargs): # code 

I’ve said several times that classes are objects, and in fact the class block is one big pile of syntactic sugar for calling type(...) with some arguments to create a new type object.

The Python documentation has a remarkably detailed description of this process, but the gist is:

• Python determines the type of the new class — the metaclass — by looking for a metaclass keyword argument. If there isn’t one, Python uses the “lowest” type among the provided base classes. (If you’re not doing anything special, that’ll just be type, since every class inherits from object and object is an instance of type.)

• Python executes the class body. It gets its own local scope, and any assignments or method definitions go into that scope.

• Python now calls type(name, bases, attrs, **kwargs). The name is whatever was right after class; the bases are position arguments; and attrs is the class body’s local scope. (This is how methods and other class attributes end up on the class.) The brand new type is then assigned to Name.

Of course, you can mess with most of this. You can implement __prepare__ on a metaclass, for example, to use a custom mapping as storage for the local scope — including any reads, which allows for some interesting shenanigans. The only part you can’t really implement in pure Python is the scoping bit, which has a couple extra rules that make sense for classes. (In particular, functions defined within a class block don’t close over the class body; that would be nonsense.)

### Object creation

Finally, there’s what actually happens when you create an object — including a class, which remember is just an invocation of type(...).

Calling Foo(...) is implemented as, well, a call. Any type can implement calls with the __call__ special method, and you’ll find that type itself does so. It looks something like this:

  1 2 3 4 5 6 7 8 9 10 11 12 13 # oh, a fun wrinkle that's hard to express in pure python: type is a class, so # it's an instance of itself class type: def __call__(self, *args, **kwargs): # remember, here 'self' is a CLASS, an instance of type. # __new__ is a true constructor: object.__new__ allocates storage # for a new blank object instance = self.__new__(self, *args, **kwargs) # you can return whatever you want from __new__ (!), and __init__ # is only called on it if it's of the right type if isinstance(instance, self): instance.__init__(*args, **kwargs) return instance 

Again, you can trivially confirm this by asking any type for its __call__ method. Assuming that type doesn’t implement __call__ itself, you’ll get back a bound version of types implementation.

 1 2 >>> list.__call__ 

You can thus implement __call__ in your own metaclass to completely change how subclasses are created — including skipping the creation altogether, if you like.

And… there’s a bunch of stuff I haven’t even touched on.

### The Python philosophy

Python offers something that, on the surface, looks like a “traditional” class/object model. Under the hood, it acts more like a prototypical system, where failed attribute lookups simply defer to a superclass or metaclass.

The language also goes to almost superhuman lengths to expose all of its moving parts. Even the prototypical behavior is an implementation of __getattribute__ somewhere, which you are free to completely replace in your own types. Proxying and delegation are easy.

Also very nice is that these features “bundle” well, by which I mean a library author can do all manner of convoluted hijinks, and a consumer of that library doesn’t have to see any of it or understand how it works. You only need to inherit from a particular class (which has a metaclass), or use some descriptor as a decorator, or even learn any new syntax.

This meshes well with Python culture, which is pretty big on the principle of least surprise. These super-advanced features tend to be tightly confined to single simple features (like “makes a weak attribute“) or cordoned with DSLs (e.g., defining a form/struct/database table with a class body). In particular, I’ve never seen a metaclass in the wild implement its own __call__.

I have mixed feelings about that. It’s probably a good thing overall that the Python world shows such restraint, but I wonder if there are some very interesting possibilities we’re missing out on. I implemented a metaclass __call__ myself, just once, in an entity/component system that strove to minimize fuss when communicating between components. It never saw the light of day, but I enjoyed seeing some new things Python could do with the same relatively simple syntax. I wouldn’t mind seeing, say, an object model based on composition (with no inheritance) built atop Python’s primitives.

## Lua

Lua doesn’t have an object model. Instead, it gives you a handful of very small primitives for building your own object model. This is pretty typical of Lua — it’s a very powerful language, but has been carefully constructed to be very small at the same time. I’ve never encountered anything else quite like it, and “but it starts indexing at 1!” really doesn’t do it justice.

The best way to demonstrate how objects work in Lua is to build some from scratch. We need two key features. The first is metatables, which bear a passing resemblance to Python’s metaclasses.

### Tables and metatables

The table is Lua’s mapping type and its primary data structure. Keys can be any value other than nil. Lists are implemented as tables whose keys are consecutive integers starting from 1. Nothing terribly surprising. The dot operator is sugar for indexing with a string key.

 1 2 3 4 5 local t = { a = 1, b = 2 } print(t['a']) -- 1 print(t.b) -- 2 t.c = 3 print(t['c']) -- 3 

A metatable is a table that can be associated with another value (usually another table) to change its behavior. For example, operator overloading is implemented by assigning a function to a special key in a metatable.

  1 2 3 4 5 6 7 8 9 10 local t = { a = 1, b = 2 } --print(t + 0) -- error: attempt to perform arithmetic on a table value local mt = { __add = function(left, right) return 12 end, } setmetatable(t, mt) print(t + 0) -- 12 

Now, the interesting part: one of the special keys is __index, which is consulted when the base table is indexed by a key it doesn’t contain. Here’s a table that claims every key maps to itself.

  1 2 3 4 5 6 7 8 9 10 local t = {} local mt = { __index = function(table, key) return key end, } setmetatable(t, mt) print(t.foo) -- foo print(t.bar) -- bar print(t[3]) -- 3 

__index doesn’t have to be a function, either. It can be yet another table, in which case that table is simply indexed with the key. If the key still doesn’t exist and that table has a metatable with an __index, the process repeats.

With this, it’s easy to have several unrelated tables that act as a single table. Call the base table an object, fill the __index table with functions and call it a class, and you have half of an object system. You can even get prototypical inheritance by chaining __indexes together.

At this point things are a little confusing, since we have at least three tables going on, so here’s a diagram. Keep in mind that Lua doesn’t actually have anything called an “object”, “class”, or “method” — those are just convenient nicknames for a particular structure we might build with Lua’s primitives.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15  ╔═══════════╗ ... ║ metatable ║ ║ ╟───────────╢ ┌─────╨───────────────────────┐ ║ __index ╫───┤ lookup table ("superclass") │ ╚═══╦═══════╝ ├─────────────────────────────┤ ╔═══════════╗ ║ │ some other method ┼─── function() ... end ║ metatable ║ ║ └─────────────────────────────┘ ╟───────────╢ ┌─────╨──────────────────┐ ║ __index ╫───┤ lookup table ("class") │ ╚═══╦═══════╝ ├────────────────────────┤ ║ │ some method ┼─── function() ... end ║ └────────────────────────┘ ┌─────╨─────────────────┐ │ base table ("object") │ └───────────────────────┘ 

Note that a metatable is not the same as a class; it defines behavior, not methods. Conversely, if you try to use a class directly as a metatable, it will probably not do much. (This is pretty different from e.g. Python, where operator overloads are just methods with funny names. One nice thing about the Lua approach is that you can keep interface-like functionality separate from methods, and avoid clogging up arbitrary objects’ namespaces. You could even use a dummy table as a key and completely avoid name collisions.)

Anyway, code!

  1 2 3 4 5 6 7 8 9 10 11 local class = { foo = function(a) print("foo got", a) end, } local mt = { __index = class } -- setmetatable returns its first argument, so this is nice shorthand local obj1 = setmetatable({}, mt) local obj2 = setmetatable({}, mt) obj1.foo(7) -- foo got 7 obj2.foo(9) -- foo got 9 

Wait, wait, hang on. Didn’t I call these methods? How do they get at the object? Maybe Lua has a magical this variable?

### Methods, sort of

Not quite, but this is where the other key feature comes in: method-call syntax. It’s the lightest touch of sugar, just enough to have method invocation.

 1 2 3 4 5 6 7 8 9 -- note the colon! a:b(c, d, ...) -- exactly equivalent to this -- (except that a is only evaluated once) a.b(a, c, d, ...) -- which of course is really this a["b"](a, c, d, ...) 

Now we can write methods that actually do something.

  1 2 3 4 5 6 7 8 9 10 local class = { bar = function(self) print("our score is", self.score) end, } local mt = { __index = class } local obj1 = setmetatable({ score = 13 }, mt) local obj2 = setmetatable({ score = 25 }, mt) obj1:bar() -- our score is 13 obj2:bar() -- our score is 25 

And that’s all you need. Much like Python, methods and data live in the same namespace, and Lua doesn’t care whether obj:method() finds a function on obj or gets one from the metatable’s __index. Unlike Python, the function will be passed self either way, because self comes from the use of : rather than from the lookup behavior.

(Aside: strictly speaking, any Lua value can have a metatable — and if you try to index a non-table, Lua will always consult the metatable’s __index. Strings all have the string library as a metatable, so you can call methods on them: try ("%s %s"):format(1, 2). I don’t think Lua lets user code set the metatable for non-tables, so this isn’t that interesting, but if you’re writing Lua bindings from C then you can wrap your pointers in metatables to give them methods implemented in C.)

### Bringing it all together

Of course, writing all this stuff every time is a little tedious and error-prone, so instead you might want to wrap it all up inside a little function. No problem.

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 local function make_object(body) -- create a metatable local mt = { __index = body } -- create a base table to serve as the object itself local obj = setmetatable({}, mt) -- and, done return obj end -- you can leave off parens if you're only passing in local Dog = { -- this acts as a "default" value; if obj.barks is missing, __index will -- kick in and find this value on the class. but if obj.barks is assigned -- to, it'll go in the object and shadow the value here. barks = 0, bark = function(self) self.barks = self.barks + 1 print("woof!") end, } local mydog = make_object(Dog) mydog:bark() -- woof! mydog:bark() -- woof! mydog:bark() -- woof! print(mydog.barks) -- 3 print(Dog.barks) -- 0 

It works, but it’s fairly barebones. The nice thing is that you can extend it pretty much however you want. I won’t reproduce an entire serious object system here — lord knows there are enough of them floating around — but the implementation I have for my LÖVE games lets me do this:

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 local Animal = Object:extend{ cries = 0, } -- called automatically by Object function Animal:init() print("whoops i couldn't think of anything interesting to put here") end -- this is just nice syntax for adding a first argument called 'self', then -- assigning this function to Animal.cry function Animal:cry() self.cries = self.cries + 1 end local Cat = Animal:extend{} function Cat:cry() print("meow!") Cat.__super.cry(self) end local cat = Cat() cat:cry() -- meow! cat:cry() -- meow! print(cat.cries) -- 2 

When I say you can extend it however you want, I mean that. I could’ve implemented Python (2)-style super(Cat, self):cry() syntax; I just never got around to it. I could even make it work with multiple inheritance if I really wanted to — or I could go the complete opposite direction and only implement composition. I could implement descriptors, customizing the behavior of individual table keys. I could add pretty decent syntax for composition/proxying. I am trying very hard to end this section now.

### The Lua philosophy

Lua’s philosophy is to… not have a philosophy? It gives you the bare minimum to make objects work, and you can do absolutely whatever you want from there. Lua does have something resembling prototypical inheritance, but it’s not so much a first-class feature as an emergent property of some very simple tools. And since you can make __index be a function, you could avoid the prototypical behavior and do something different entirely.

The very severe downside, of course, is that you have to find or build your own object system — which can get pretty confusing very quickly, what with the multiple small moving parts. Third-party code may also have its own object system with subtly different behavior. (Though, in my experience, third-party code tries very hard to avoid needing an object system at all.)

It’s hard to say what the Lua “culture” is like, since Lua is an embedded language that’s often a little different in each environment. I imagine it has a thousand millicultures, instead. I can say that the tedium of building my own object model has led me into something very “traditional”, with prototypical inheritance and whatnot. It’s partly what I’m used to, but it’s also just really dang easy to get working.

Likewise, while I love properties in Python and use them all the dang time, I’ve yet to use a single one in Lua. They wouldn’t be particularly hard to add to my object model, but having to add them myself (or shop around for an object model with them and also port all my code to use it) adds a huge amount of friction. I’ve thought about designing an interesting ECS with custom object behavior, too, but… is it really worth the effort? For all the power and flexibility Lua offers, the cost is that by the time I have something working at all, I’m too exhausted to actually use any of it.

## JavaScript

JavaScript is notable for being preposterously heavily used, yet not having a class block.

Well. Okay. Yes. It has one now. It didn’t for a very long time, and even the one it has now is sugar.

Here’s a vector class again:

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 class Vector { constructor(x, y) { this.x = x; this.y = y; } get magnitude() { return Math.sqrt(this.x * this.x + this.y * this.y); } dot(other) { return this.x * other.x + this.y * other.y; } } 

In “classic” JavaScript, this would be written as:

  1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 function Vector(x, y) { this.x = x; this.y = y; } Object.defineProperty(Vector.prototype, 'magnitude', { configurable: true, enumerable: true, get: function() { return Math.sqrt(this.x * this.x + this.y * this.y); }, }); Vector.prototype.dot = function(other) { return this.x * other.x + this.y * other.y; }; 

Hm, yes. I can see why they added class.

### The JavaScript model

In JavaScript, a new type is defined in terms of a function, which is its constructor.

Right away we get into trouble here. There is a very big difference between these two invocations, which I actually completely forgot about just now after spending four hours writing about Python and Lua:

 1 2 let vec = Vector(3, 4); let vec = new Vector(3, 4); 

The first calls the function Vector. It assigns some properties to this, which here is going to be window, so now you have a global x and y. It then returns nothing, so vec is undefined.

The second calls Vector with this set to a new empty object, then evaluates to that object. The result is what you’d actually expect.

(You can detect this situation with the strange new.target expression, but I have never once remembered to do so.)

From here, we have true, honest-to-god, first-class prototypical inheritance. The word “prototype” is even right there. When you write this:

 1 vec.dot(vec2) 

JavaScript will look for dot on vec and (presumably) not find it. It then consults vecs prototype, an object you can see for yourself by using Object.getPrototypeOf(). Since vec is a Vector, its prototype is Vector.prototype.

I stress that Vector.prototype is not the prototype for Vector. It’s the prototype for instances of Vector.

(I say “instance”, but the true type of vec here is still just object. If you want to find Vector, it’s automatically assigned to the constructor property of its own prototype, so it’s available as vec.constructor.)

Of course, Vector.prototype can itself have a prototype, in which case the process would continue if dot were not found. A common (and, arguably, very bad) way to simulate single inheritance is to set Class.prototype to an instance of a superclass to get the prototype right, then tack on the methods for Class. Nowadays we can do Object.create(Superclass.prototype).

Now that I’ve been through Python and Lua, though, this isn’t particularly surprising. I kinda spoiled it.

I suppose one difference in JavaScript is that you can tack arbitrary attributes directly onto Vector all you like, and they will remain invisible to instances since they aren’t in the prototype chain. This is kind of backwards from Lua, where you can squirrel stuff away in the metatable.

Another difference is that every single object in JavaScript has a bunch of properties already tacked on — the ones in Object.prototype. Every object (and by “object” I mean any mapping) has a prototype, and that prototype defaults to Object.prototype, and it has a bunch of ancient junk like isPrototypeOf.

(Nit: it’s possible to explicitly create an object with no prototype via Object.create(null).)

Like Lua, and unlike Python, JavaScript doesn’t distinguish between keys found on an object and keys found via a prototype. Properties can be defined on prototypes with Object.defineProperty(), but that works just as well directly on an object, too. JavaScript doesn’t have a lot of operator overloading, but some things like Symbol.iterator also work on both objects and prototypes.

### About this

You may, at this point, be wondering what this is. Unlike Lua and Python (and the last language below), this is a special built-in value — a context value, invisibly passed for every function call.

It’s determined by where the function came from. If the function was the result of an attribute lookup, then this is set to the object containing that attribute. Otherwise, this is set to the global object, window. (You can also set this to whatever you want via the call method on functions.)

This decision is made lexically, i.e. from the literal source code as written. There are no Python-style bound methods. In other words:

 1 2 3 4 5 // this = obj obj.method() // this = window let meth = obj.method meth() 

Also, because this is reassigned on every function call, it cannot be meaningfully closed over, which makes using closures within methods incredibly annoying. The old approach was to assign this to some other regular name like self (which got syntax highlighting since it’s also a built-in name in browsers); then we got Function.bind, which produced a callable thing with a fixed context value, which was kind of nice; and now finally we have arrow functions, which explicitly close over the current this when they’re defined and don’t change it when called. Phew.

### Class syntax

I already showed class syntax, and it’s really just one big macro for doing all the prototype stuff The Right Way. It even prevents you from calling the type without new. The underlying model is exactly the same, and you can inspect all the parts.

  1 2 3 4 5 6 7 8 9 10 11 class Vector { ... } console.log(Vector.prototype); // { dot: ..., magnitude: ..., ... } let vec = new Vector(3, 4); console.log(Object.getPrototypeOf(vec)); // same as Vector.prototype // i don't know why you would subclass vector but let's roll with it class Vectest extends Vector { ... } console.log(Vectest.prototype); // { ... } console.log(Object.getPrototypeOf(Vectest.prototype)) // same as Vector.prototype 

Alas, class syntax has a couple shortcomings. You can’t use the class block to assign arbitrary data to either the type object or the prototype — apparently it was deemed too confusing that mutations would be shared among instances. Which… is… how prototypes work. How Python works. How JavaScript itself, one of the most popular languages of all time, has worked for twenty-two years. Argh.

You can still do whatever assignment you want outside of the class block, of course. It’s just a little ugly, and not something I’d think to look for with a sugary class.

A more subtle result of this behavior is that a class block isn’t quite the same syntax as an object literal. The check for data isn’t a runtime thing; class Foo { x: 3 } fails to parse. So JavaScript now has two largely but not entirely identical styles of key/value block.

### Attribute access

Here’s where things start to come apart at the seams, just a little bit.

JavaScript doesn’t really have an attribute protocol. Instead, it has two… extension points, I suppose.

One is Object.defineProperty, seen above. For common cases, there’s also the get syntax inside a property literal, which does the same thing. But unlike Python’s @property, these aren’t wrappers around some simple primitives; they are the primitives. JavaScript is the only language of these four to have “property that runs code on access” as a completely separate first-class concept.

If you want to intercept arbitrary attribute access (and some kinds of operators), there’s a completely different primitive: the Proxy type. It doesn’t let you intercept attribute access or operators; instead, it produces a wrapper object that supports interception and defers to the wrapped object by default.

It’s cool to see composition used in this way, but also, extremely weird. If you want to make your own type that overloads in or calling, you have to return a Proxy that wraps your own type, rather than actually returning your own type. And (unlike the other three languages in this post) you can’t return a different type from a constructor, so you have to throw that away and produce objects only from a factory. And instanceof would be broken, but you can at least fix that with Symbol.hasInstance — which is really operator overloading, implement yet another completely different way.

I know the design here is a result of legacy and speed — if any object could intercept all attribute access, then all attribute access would be slowed down everywhere. Fair enough. It still leaves the surface area of the language a bit… bumpy?

### The JavaScript philosophy

It’s a little hard to tell. The original idea of prototypes was interesting, but it was hidden behind some very awkward syntax. Since then, we’ve gotten a bunch of extra features awkwardly bolted on to reflect the wildly varied things the built-in types and DOM API were already doing. We have class syntax, but it’s been explicitly designed to avoid exposing the prototype parts of the model.

I admit I don’t do a lot of heavy JavaScript, so I might just be overlooking it, but I’ve seen virtually no code that makes use of any of the recent advances in object capabilities. Forget about custom iterators or overloading call; I can’t remember seeing any JavaScript in the wild that even uses properties yet. I don’t know if everyone’s waiting for sufficient browser support, nobody knows about them, or nobody cares.

The model has advanced recently, but I suspect JavaScript is still shackled to its legacy of “something about prototypes, I don’t really get it, just copy the other code that’s there” as an object model. Alas! Prototypes are so good. Hopefully class syntax will make it a bit more accessible, as it has in Python.

## Perl 5

Perl 5 also doesn’t have an object system and expects you to build your own. But where Lua gives you two simple, powerful tools for building one, Perl 5 feels more like a puzzle with half the pieces missing. Clearly they were going for something, but they only gave you half of it.

In brief, a Perl object is a reference that has been blessed with a package.

I need to explain a few things. Honestly, one of the biggest problems with the original Perl object setup was how many strange corners and unique jargon you had to understand just to get off the ground.

(If you want to try running any of this code, you should stick a use v5.26; as the first line. Perl is very big on backwards compatibility, so you need to opt into breaking changes, and even the mundane say builtin is behind a feature gate.)

A few things of note here. First, $self->[0] has nothing to do with objects; it’s normal syntax for getting the value of a index 0 out of an array reference called $self. (Most classes are based on hashrefs and would use $self->{value} instead.) A blessed reference is still a reference and can be treated like one. In general, -> is Perl’s dereferencey operator, but its exact behavior depends on what follows. If it’s followed by brackets, then it’ll apply the brackets to the thing in the reference: ->{} to index a hash reference, ->[] to index an array reference, and ->() to call a function reference. But if -> is followed by an identifier, then it’s a method call. For packages, that means calling a function in the package and passing the package name as the first argument. For objects — blessed references — that means calling a function in the associated package and passing the object as the first argument. This is a little weird! A blessed reference is a superposition of two things: its normal reference behavior, and some completely orthogonal object behavior. Also, object behavior has no notion of methods vs data; it only knows about methods. Perl lets you omit parentheses in a lot of places, including when calling a method with no arguments, so $vec->magnitude is really $vec->magnitude(). Perl’s blessing bears some similarities to Lua’s metatables, but ultimately Perl is much closer to Ruby’s “message passing” approach than the above three languages’ approaches of “get me something and maybe it’ll be callable”. (But this is no surprise — Ruby is a spiritual successor to Perl 5.) All of this leads to one little wrinkle: how do you actually expose data? Above, I had to write x and y methods. Am I supposed to do that for every single attribute on my type? Yes! But don’t worry, there are third-party modules to help with this incredibly fundamental task. Take Class::Accessor::Fast, so named because it’s faster than Class::Accessor:  1 2 3 package Foo; use base qw(Class::Accessor::Fast); __PACKAGE__->mk_accessors(qw(fred wilma barney));  (__PACKAGE__ is the lexical name of the current package; qw(...) is a list literal that splits its contents on whitespace.) This assumes you’re using a hashref with keys of the same names as the attributes. $obj->fred will return the fred key from your hashref, and $obj->fred(4) will change it to 4. You also, somewhat bizarrely, have to inherit from Class::Accessor::Fast. Speaking of which, ### Inheritance Inheritance is done by populating the package-global @ISA array with some number of (string) names of parent packages. Most code instead opts to write use base ...;, which does the same thing. Or, more commonly, use parent ...;, which… also… does the same thing. Every package implicitly inherits from UNIVERSAL, which can be freely modified by Perl code. A method can call its superclass method with the SUPER:: pseudo-package:  1 2 3 4 sub foo { my ($self) = @_; $self->SUPER::foo; }  However, this does a depth-first search, which means it almost certainly does the wrong thing when faced with multiple inheritance. For a while the accepted solution involved a third-party module, but Perl eventually grew an alternative you have to opt into: C3, which may be more familiar to you as the order Python uses.  1 2 3 4 5 6 use mro 'c3'; sub foo { my ($self) = @_; $self->next::method; }  Offhand, I’m not actually sure how next::method works, seeing as it was originally implemented in pure Perl code. I suspect it involves peeking at the caller’s stack frame. If so, then this is a very different style of customizability from e.g. Python — the MRO was never intended to be pluggable, and the use of a special pseudo-package means it isn’t really, but someone was determined enough to make it happen anyway. ### Operator overloading and whatnot Operator overloading looks a little weird, though really it’s pretty standard Perl.  1 2 3 4 5 6 7 8 package MyClass; use overload '+' => \&_add; sub _add { my ($self, $other,$swap) = @_; ... } 

use overload here is a pragma, where “pragma” means “regular-ass module that does some wizardry when imported”.

\&_add is how you get a reference to the _add sub so you can pass it to the overload module. If you just said &_add or _add, that would call it.

And that’s it; you just pass a map of operators to functions to this built-in module. No worry about name clashes or pollution, which is pretty nice. You don’t even have to give references to functions that live in the package, if you don’t want them to clog your namespace; you could put them in another package, or even inline them anonymously.

One especially interesting thing is that Perl lets you overload every operator. Perl has a lot of operators. It considers some math builtins like sqrt and trig functions to be operators, or at least operator-y enough that you can overload them. You can also overload the “file text” operators, such as -e $path to test whether a file exists. You can overload conversions, including implicit conversion to a regex. And most fascinating to me, you can overload dereferencing — that is, the thing Perl does when you say $hashref->{key} to get at the underlying hash. So a single object could pretend to be references of multiple different types, including a subref to implement callability. Neat.

Somewhat related: you can overload basic operators (indexing, etc.) on basic types (not references!) with the tie function, which is designed completely differently and looks for methods with fixed names. Go figure.

You can intercept calls to nonexistent methods by implementing a function called AUTOLOAD, within which the $AUTOLOAD global will contain the name of the method being called. Originally this feature was, I think, intended for loading binary components or large libraries on-the-fly only when needed, hence the name. Offhand I’m not sure I ever saw it used the way __getattr__ is used in Python. Is there a way to intercept all method calls? I don’t think so, but it is Perl, so I must be forgetting something. ### Actually no one does this any more Like a decade ago, a council of elder sages sat down and put together a whole whizbang system that covers all of it: Moose.   1 2 3 4 5 6 7 8 9 10 package Vector; use Moose; has x => (is => 'rw', isa => 'Int'); has y => (is => 'rw', isa => 'Int'); sub magnitude { my ($self) = @_; return sqrt($self->x ** 2 +$self->y ** 2); } 

Moose has its own way to do pretty much everything, and it’s all built on the same primitives. Moose also adds metaclasses, somehow, despite that the underlying model doesn’t actually support them? I’m not entirely sure how they managed that, but I do remember doing some class introspection with Moose and it was much nicer than the built-in way.

(If you’re wondering, the built-in way begins with looking at the hash called %Vector::. No, that’s not a typo.)

I really cannot stress enough just how much stuff Moose does, but I don’t want to delve into it here since Moose itself is not actually the language model.

### The Perl philosophy

I hope you can see what I meant with what I first said about Perl, now. It has multiple inheritance with an MRO, but uses the wrong one by default. It has extensive operator overloading, which looks nothing like how inheritance works, and also some of it uses a totally different mechanism with special method names instead. It only understands methods, not data, leaving you to figure out accessors by hand.

There’s 70% of an object system here with a clear general design it was gunning for, but none of the pieces really look anything like each other. It’s weird, in a distinctly Perl way.

The result is certainly flexible, at least! It’s especially cool that you can use whatever kind of reference you want for storage, though even as I say that, I acknowledge it’s no different from simply subclassing list or something in Python. It feels different in Perl, but maybe only because it looks so different.

I haven’t written much Perl in a long time, so I don’t know what the community is like any more. Moose was already ubiquitous when I left, which you’d think would let me say “the community mostly focuses on the stuff Moose can do” — but even a decade ago, Moose could already do far more than I had ever seen done by hand in Perl. It’s always made a big deal out of roles (read: interfaces), for instance, despite that I’d never seen anyone care about them in Perl before Moose came along. Maybe their presence in Moose has made them more popular? Who knows.

Also, I wrote Perl seriously, but in the intervening years I’ve only encountered people who only ever used Perl for one-offs. Maybe it’ll come as a surprise to a lot of readers that Perl has an object model at all.

## End

Well, that was fun! I hope any of that made sense.

Special mention goes to Rust, which doesn’t have an object model you can fiddle with at runtime, but does do things a little differently.

It’s been really interesting thinking about how tiny differences make a huge impact on what people do in practice. Take the choice of storage in Perl versus Python. Perl’s massively common URI class uses a string as the storage, nothing else; I haven’t seen anything like that in Python aside from markupsafe, which is specifically designed as a string type. I would guess this is partly because Perl makes you choose — using a hashref is an obvious default, but you have to make that choice one way or the other. In Python (especially 3), inheriting from object and getting dict-based storage is the obvious thing to do; the ability to use another type isn’t quite so obvious, and doing it “right” involves a tiny bit of extra work.

Or, consider that Lua could have descriptors, but the extra bit of work (especially design work) has been enough of an impediment that I’ve never implemented them. I don’t think the object implementations I’ve looked at have included them, either. Super weird!

In that light, it’s only natural that objects would be so strongly associated with the features Java and C++ attach to them. I think that makes it all the more important to play around! Look at what Moose has done. No, really, you should bear in mind my description of how Perl does stuff and flip through the Moose documentation. It’s amazing what they’ve built.

# Potential impact of the Intel ME vulnerability

Post Syndicated from Matthew Garrett original https://mjg59.dreamwidth.org/49611.html

(Note: this is my personal opinion based on public knowledge around this issue. I have no knowledge of any non-public details of these vulnerabilities, and this should not be interpreted as the position or opinion of my employer)

Intel’s Management Engine (ME) is a small coprocessor built into the majority of Intel CPUs[0]. Older versions were based on the ARC architecture[1] running an embedded realtime operating system, but from version 11 onwards they’ve been small x86 cores running Minix. The precise capabilities of the ME have not been publicly disclosed, but it is at minimum capable of interacting with the network[2], display[3], USB, input devices and system flash. In other words, software running on the ME is capable of doing a lot, without requiring any OS permission in the process.

Back in May, Intel announced a vulnerability in the Advanced Management Technology (AMT) that runs on the ME. AMT offers functionality like providing a remote console to the system (so IT support can connect to your system and interact with it as if they were physically present), remote disk support (so IT support can reinstall your machine over the network) and various other bits of system management. The vulnerability meant that it was possible to log into systems with enabled AMT with an empty authentication token, making it possible to log in without knowing the configured password.

This vulnerability was less serious than it could have been for a couple of reasons – the first is that “consumer”[4] systems don’t ship with AMT, and the second is that AMT is almost always disabled (Shodan found only a few thousand systems on the public internet with AMT enabled, out of many millions of laptops). I wrote more about it here at the time.

How does this compare to the newly announced vulnerabilities? Good question. Two of the announced vulnerabilities are in AMT. The previous AMT vulnerability allowed you to bypass authentication, but restricted you to doing what AMT was designed to let you do. While AMT gives an authenticated user a great deal of power, it’s also designed with some degree of privacy protection in mind – for instance, when the remote console is enabled, an animated warning border is drawn on the user’s screen to alert them.

This vulnerability is different in that it allows an authenticated attacker to execute arbitrary code within the AMT process. This means that the attacker shouldn’t have any capabilities that AMT doesn’t, but it’s unclear where various aspects of the privacy protection are implemented – for instance, if the warning border is implemented in AMT rather than in hardware, an attacker could duplicate that functionality without drawing the warning. If the USB storage emulation for remote booting is implemented as a generic USB passthrough, the attacker could pretend to be an arbitrary USB device and potentially exploit the operating system through bugs in USB device drivers. Unfortunately we don’t currently know.

Note that this exploit still requires two things – first, AMT has to be enabled, and second, the attacker has to be able to log into AMT. If the attacker has physical access to your system and you don’t have a BIOS password set, they will be able to enable it – however, if AMT isn’t enabled and the attacker isn’t physically present, you’re probably safe. But if AMT is enabled and you haven’t patched the previous vulnerability, the attacker will be able to access AMT over the network without a password and then proceed with the exploit. This is bad, so you should probably (1) ensure that you’ve updated your BIOS and (2) ensure that AMT is disabled unless you have a really good reason to use it.

The AMT vulnerability applies to a wide range of versions, everything from version 6 (which shipped around 2008) and later. The other vulnerability that Intel describe is restricted to version 11 of the ME, which only applies to much more recent systems. This vulnerability allows an attacker to execute arbitrary code on the ME, which means they can do literally anything the ME is able to do. This probably also means that they are able to interfere with any other code running on the ME. While AMT has been the most frequently discussed part of this, various other Intel technologies are tied to ME functionality.

Intel’s Platform Trust Technology (PTT) is a software implementation of a Trusted Platform Module (TPM) that runs on the ME. TPMs are intended to protect access to secrets and encryption keys and record the state of the system as it boots, making it possible to determine whether a system has had part of its boot process modified and denying access to the secrets as a result. The most common usage of TPMs is to protect disk encryption keys – Microsoft Bitlocker defaults to storing its encryption key in the TPM, automatically unlocking the drive if the boot process is unmodified. In addition, TPMs support something called Remote Attestation (I wrote about that here), which allows the TPM to provide a signed copy of information about what the system booted to a remote site. This can be used for various purposes, such as not allowing a compute node to join a cloud unless it’s booted the correct version of the OS and is running the latest firmware version. Remote Attestation depends on the TPM having a unique cryptographic identity that is tied to the TPM and inaccessible to the OS.

PTT allows manufacturers to simply license some additional code from Intel and run it on the ME rather than having to pay for an additional chip on the system motherboard. This seems great, but if an attacker is able to run code on the ME then they potentially have the ability to tamper with PTT, which means they can obtain access to disk encryption secrets and circumvent Bitlocker. It also means that they can tamper with Remote Attestation, “attesting” that the system booted a set of software that it didn’t or copying the keys to another system and allowing that to impersonate the first. This is, uh, bad.

Intel also recently announced Intel Online Connect, a mechanism for providing the functionality of security keys directly in the operating system. Components of this are run on the ME in order to avoid scenarios where a compromised OS could be used to steal the identity secrets – if the ME is compromised, this may make it possible for an attacker to obtain those secrets and duplicate the keys.

It’s also not entirely clear how much of Intel’s Secure Guard Extensions (SGX) functionality depends on the ME. The ME does appear to be required for SGX Remote Attestation (which allows an application using SGX to prove to a remote site that it’s the SGX app rather than something pretending to be it), and again if those secrets can be extracted from a compromised ME it may be possible to compromise some of the security assumptions around SGX. Again, it’s not clear how serious this is because it’s not publicly documented.

Various other things also run on the ME, including stuff like video DRM (ensuring that high resolution video streams can’t be intercepted by the OS). It may be possible to obtain encryption keys from a compromised ME that allow things like Netflix streams to be decoded and dumped. From a user privacy or security perspective, these things seem less serious.

The big problem at the moment is that we have no idea what the actual process of compromise is. Intel state that it requires local access, but don’t describe what kind. Local access in this case could simply require the ability to send commands to the ME (possible on any system that has the ME drivers installed), could require direct hardware access to the exposed ME (which would require either kernel access or the ability to install a custom driver) or even the ability to modify system flash (possible only if the attacker has physical access and enough time and skill to take the system apart and modify the flash contents with an SPI programmer). The other thing we don’t know is whether it’s possible for an attacker to modify the system such that the ME is persistently compromised or whether it needs to be re-compromised every time the ME reboots. Note that even the latter is more serious than you might think – the ME may only be rebooted if the system loses power completely, so even a “temporary” compromise could affect a system for a long period of time.

It’s also almost impossible to determine if a system is compromised. If the ME is compromised then it’s probably possible for it to roll back any firmware updates but still report that it’s been updated, giving admins a false sense of security. The only way to determine for sure would be to dump the system flash and compare it to a known good image. This is impractical to do at scale.

So, overall, given what we know right now it’s hard to say how serious this is in terms of real world impact. It’s unlikely that this is the kind of vulnerability that would be used to attack individual end users – anyone able to compromise a system like this could just backdoor your browser instead with much less effort, and that already gives them your banking details. The people who have the most to worry about here are potential targets of skilled attackers, which means activists, dissidents and companies with interesting personal or business data. It’s hard to make strong recommendations about what to do here without more insight into what the vulnerability actually is, and we may not know that until this presentation next month.

Summary: Worst case here is terrible, but unlikely to be relevant to the vast majority of users.

[0] Earlier versions of the ME were built into the motherboard chipset, but as portions of that were incorporated onto the CPU package the ME followed
[1] A descendent of the SuperFX chip used in Super Nintendo cartridges such as Starfox, because why not
[2] Without any OS involvement for wired ethernet and for wireless networks in the system firmware, but requires OS support for wireless access once the OS drivers have loaded
[3] Assuming you’re using integrated Intel graphics
[4] “Consumer” is a bit of a misnomer here – “enterprise” laptops like Thinkpads ship with AMT, but are often bought by consumers.

comments

# [$] Replacing x86 firmware with Linux and Go Post Syndicated from jake original https://lwn.net/Articles/738649/rss The Intel Management Engine (ME), which is a separate processor and operating system running outside of user control on most x86 systems, has long been of concern to users who are security and privacy conscious. Google and others have been working on ways to eliminate as much of that functionality as possible (while still being able to boot and run the system). Ronald Minnich from Google came to Prague to talk about those efforts at the 2017 Embedded Linux Conference Europe. # How AWS Managed Microsoft AD Helps to Simplify the Deployment and Improve the Security of Active Directory–Integrated .NET Applications Companies using .NET applications to access sensitive user information, such as employee salary, Social Security Number, and credit card information, need an easy and secure way to manage access for users and applications. For example, let’s say that your company has a .NET payroll application. You want your Human Resources (HR) team to manage and update the payroll data for all the employees in your company. You also want your employees to be able to see their own payroll information in the application. To meet these requirements in a user-friendly and secure way, you want to manage access to the .NET application by using your existing Microsoft Active Directory identities. This enables you to provide users with single sign-on (SSO) access to the .NET application and to manage permissions using Active Directory groups. You also want the .NET application to authenticate itself to access the database, and to limit access to the data in the database based on the identity of the application user. Microsoft Active Directory supports these requirements through group Managed Service Accounts (gMSAs) and Kerberos constrained delegation (KCD). AWS Directory Service for Microsoft Active Directory, also known as AWS Managed Microsoft AD, enables you to manage gMSAs and KCD through your administrative account, helping you to migrate and develop .NET applications that need these native Active Directory features. In this blog post, I give an overview of how to use AWS Managed Microsoft AD to manage gMSAs and KCD and demonstrate how you can configure a gMSA and KCD in six steps for a .NET application: 1. Create your AWS Managed Microsoft AD. 2. Create your Amazon RDS for SQL Server database. 3. Create a gMSA for your .NET application. 4. Deploy your .NET application. 5. Configure your .NET application to use the gMSA. 6. Configure KCD for your .NET application. ### Solution overview The following diagram shows the components of a .NET application that uses Amazon RDS for SQL Server with a gMSA and KCD. The diagram also illustrates authentication and access and is numbered to show the six key steps required to use a gMSA and KCD. To deploy this solution, the AWS Managed Microsoft AD directory must be in the same Amazon Virtual Private Cloud (VPC) as RDS for SQL Server. For this example, my company name is Example Corp., and my directory uses the domain name, example.com. ### Deploy the solution The following six steps (numbered to correlate with the preceding diagram) walk you through configuring and using a gMSA and KCD. #### 1. Create your AWS Managed Microsoft AD directory Using the Directory Service console, create your AWS Managed Microsoft AD directory in your Amazon VPC. In my example, my domain name is example.com. #### 2. Create your Amazon RDS for SQL Server database Using the RDS console, create your Amazon RDS for SQL Server database instance in the same Amazon VPC where your directory is running, and enable Windows Authentication. To enable Windows Authentication, select your directory in the Microsoft SQL Server Windows Authentication section in the Configure Advanced Settings step of the database creation workflow (see the following screenshot). In my example, I create my Amazon RDS for SQL Server db-example database, and enable Windows Authentication to allow my db-example database to authenticate against my example.com directory. #### 3. Create a gMSA for your .NET application Now that you have deployed your directory, database, and application, you can create a gMSA for your .NET application. To perform the next steps, you must install the Active Directory administration tools on a Windows server that is joined to your AWS Managed Microsoft AD directory domain. If you do not have a Windows server joined to your directory domain, you can deploy a new Amazon EC2 for Microsoft Windows Server instance and join it to your directory domain. To create a gMSA for your .NET application: 1. Log on to the instance on which you installed the Active Directory administration tools by using a user that is a member of the Admins security group or the Managed Service Accounts Admins security group in your organizational unit (OU). For my example, I use the Admin user in the example OU. 1. Identify which .NET application servers (hosts) will run your .NET application. Create a new security group in your OU and add your .NET application servers as members of this new group. This allows a group of application servers to use a single gMSA, instead of creating one gMSA for each server. In my example, I create a group, App_server_grp, in my example OU. I also add Appserver1, which is my .NET application server computer name, as a member of this new group. 1. Create a gMSA in your directory by running Windows PowerShell from the Start menu. The basic syntax to create the gMSA at the Windows PowerShell command prompt follows. PS C:\Users\admin> New-ADServiceAccount -name [gMSAname] -DNSHostName [domainname] -PrincipalsAllowedToRetrieveManagedPassword [AppServersSecurityGroup] -TrustedForDelegation$truedn <Enter>

In my example, the gMSAname is gMSAexample, the DNSHostName is example.com, and the PrincipalsAllowedToRetrieveManagedPassword is the recently created security group, App_server_grp.

PS C:\Users\admin> New-ADServiceAccount -name gMSAexample -DNSHostName example.com -PrincipalsAllowedToRetrieveManagedPassword App_server_grp -TrustedForDelegation $truedn <Enter> To confirm you created the gMSA, you can run the Get-ADServiceAccount command from the PowerShell command prompt. PS C:\Users\admin> Get-ADServiceAccount gMSAexample <Enter> DistinguishedName : CN=gMSAexample,CN=Managed Service Accounts,DC=example,DC=com Enabled : True Name : gMSAexample ObjectClass : msDS-GroupManagedServiceAccount ObjectGUID : 24d8b68d-36d5-4dc3-b0a9-edbbb5dc8a5b SamAccountName : gMSAexample$
SID               : S-1-5-21-2100421304-991410377-951759617-1603
UserPrincipalName :

You also can confirm you created the gMSA by opening the Active Directory Users and Computers utility located in your Administrative Tools folder, expand the domain (example.com in my case), and expand the Managed Service Accounts folder.

#### 4. Deploy your .NET application

Deploy your .NET application on IIS on Amazon EC2 for Windows Server instances. For this step, I assume you are the application’s expert and already know how to deploy it. Make sure that all of your instances are joined to your directory.

#### 5. Configure your .NET application to use the gMSA

You can configure your .NET application to use the gMSA to enforce strong password security policy and ensure password rotation of your service account. This helps to improve the security and simplify the management of your .NET application. Configure your .NET application in two steps:

1. Grant to gMSA the required permissions to run your .NET application in the respective application folders. This is a critical step because when you change the application pool identity account to use gMSA, downtime can occur if the gMSA does not have the application’s required permissions. Therefore, make sure you first test the configurations in your development and test environments.
2. Configure your application pool identity on IIS to use the gMSA as the service account. When you configure a gMSA as the service account, you include the $ at the end of the gMSA name. You do not need to provide a password because AWS Managed Microsoft AD automatically creates and rotates the password. In my example, my service account is gMSAexample$, as shown in the following screenshot.

You have completed all the steps to use gMSA to create and rotate your .NET application service account password! Now, you will configure KCD for your .NET application.

#### 6. Configure KCD for your .NET application

You now are ready to allow your .NET application to have access to other services by using the user identity’s permissions instead of the application service account’s permissions. Note that KCD and gMSA are independent features, which means you do not have to create a gMSA to use KCD. For this example, I am using both features to show how you can use them together. To configure a regular service account such as a user or local built-in account, see the Kerberos constrained delegation with ASP.NET blog post on MSDN.

In my example, my goal is to delegate to the gMSAexample account the ability to enforce the user’s permissions to my db-example SQL Server database, instead of the gMSAexample account’s permissions. For this, I have to update the msDS-AllowedToDelegateTo gMSA attribute. The value for this attribute is the service principal name (SPN) of the service instance that you are targeting, which in this case is the db-example Amazon RDS for SQL Server database.

The SPN format for the msDS-AllowedToDelegateTo attribute is a combination of the service class, the Kerberos authentication endpoint, and the port number. The Amazon RDS for SQL Server Kerberos authentication endpoint format is [database_name].[domain_name]. The value for my msDS-AllowedToDelegateTo attribute is MSSQLSvc/db-example.example.com:1433, where MSSQLSvc and 1433 are the SQL Server Database service class and port number standards, respectively.

Follow these steps to perform the msDS-AllowedToDelegateTo gMSA attribute configuration:

1. Log on to your Active Directory management instance with a user identity that is a member of the Kerberos Delegation Admins security group. In this case, I will use admin.
2. Open the Active Directory Users and Groups utility located in your Administrative Tools folder, choose View, and then choose Advanced Features.
3. Expand your domain name (example.com in this example), and then choose the Managed Service Accounts security group. Right-click the gMSA account for the application pool you want to enable for Kerberos delegation, choose Properties, and choose the Attribute Editor tab.
4. Search for the msDS-AllowedToDelegateTo attribute on the Attribute Editor tab and choose Edit.
5. Enter the MSSQLSvc/db-example.example.com:1433 value and choose Add.
6. Choose OK and Apply, and your KCD configuration is complete.

Congratulations! At this point, your application is using a gMSA rather than an embedded static user identity and password, and the application is able to access SQL Server using the identity of the application user. The gMSA eliminates the need for you to rotate the application’s password manually, and it allows you to better scope permissions for the application. When you use KCD, you can enforce access to your database consistently based on user identities at the database level, which prevents improper access that might otherwise occur because of an application error.

#### Summary

In this blog post, I demonstrated how to simplify the deployment and improve the security of your .NET application by using a group Managed Service Account and Kerberos constrained delegation with your AWS Managed Microsoft AD directory. I also outlined the main steps to get your .NET environment up and running on a managed Active Directory and SQL Server infrastructure. This approach will make it easier for you to build new .NET applications in the AWS Cloud or migrate existing ones in a more secure way.

For additional information about using group Managed Service Accounts and Kerberos constrained delegation with your AWS Managed Microsoft AD directory, see the AWS Directory Service documentation.

To learn more about AWS Directory Service, see the AWS Directory Service home page. If you have questions about this post or its solution, start a new thread on the Directory Service forum.

– Peter