Tag Archives: BBC

Securely tailor your TV viewing with BBC Box and Raspberry Pi

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/securely-tailor-your-tv-viewing-with-bbc-box-and-raspberry-pi/

Thanks to BBC Box, you might be able to enjoy personalised services without giving up all your data. Sean McManus reports:

One day, you could watch TV shows that are tailored to your interests, thanks to BBC Box. It pulls together personal data from different sources in a household device, and gives you control over which apps may access it.

“If we were to create a device like BBC Box and put it out there, it would allow us to create personalised services without holding personal data,” says Max Leonard.

TV shows could be edited on the device to match the user’s interests, without those interests being disclosed to the BBC. One user might see more tech news and less sport news, for example.

BBC Box was partly inspired by a change in the law that gives us all the right to reuse data that companies hold on us. “You can pull out data dumps, but it’s difficult to do anything with them unless you’re a data scientist,” explains Max. “We’re trying to create technologies to enable people to do interesting things with their data, and allow organisations to create services based on that data on your behalf.”

Building the box

BBC Box is based on Raspberry Pi 3B+, the most powerful model available when this project began. “Raspberry Pi is an amazing prototyping platform,” says Max. “Relatively powerful, inexpensive, with GPIO, and able to run a proper OS. Most importantly, it can fit inside a small box!”

That prototype box is a thing of beauty, a hexagonal tube made of cedar wood. “We created a set of principles for experience and interaction with BBC Box and themes of strength, protection, and ownership came out very strongly,” says Jasmine Cox. “We looked at shapes in nature and architecture that were evocative of these themes (beehives, castles, triangles) and played with how they could be a housing for Raspberry Pi.”

The core software for collating and managing access to data is called Databox. Alpine Linux was chosen because it’s “lightweight, speedy but most importantly secure”, in Max’s words. To get around problems making GPIO access work on Alpine Linux, an Arduino Nano is used to control the LEDs. Storage is a 64GB microSD card, and apps run inside Docker containers, which helps to isolate them from each other.

Combining data securely

The BBC has piloted two apps based on BBC Box. One collects your preferred type of TV programme from BBC iPlayer and your preferred music genre from Spotify. That unique combination of data can be used to recommend events you might like from Skiddle’s database.

Another application helps two users to plan a holiday together. It takes their individual preferences and shows them the destinations they both want to visit, with information about them brought in from government and commercial sources. The app protects user privacy, because neither user has to reveal places they’d rather not visit to the other user, or the reason why.

The team is now testing these concepts with users and exploring future technology options for BBC Box.

The MagPi magazine

This article was lovingly yoinked from the latest issue of The MagPi magazine. You can read issue 87 today, for free, right now, by visiting The MagPi website.

You can also purchase issue 87 from the Raspberry Pi Press website with free worldwide delivery, from the Raspberry Pi Store, Cambridge, and from newsagents and supermarkets across the UK.

 

The post Securely tailor your TV viewing with BBC Box and Raspberry Pi appeared first on Raspberry Pi.

iplayer: тест за обществена значимост на услугите на обществените медии

Post Syndicated from nellyo original https://nellyo.wordpress.com/2019/04/27/iplayer/

В Обединеното кралство всяка нова услуга преминава през тест за съответствие с обществената мисия от две части. През тест преминават и исканията за съществени промени.  Британският регулатор е поискал от обществената телевизия Би Би Си да проведе тест за обществена значимост (PIT), за да позволи публично разглеждане на промените в услугата  iPlayer на BBC.

Би Би Си отговаря, че планираните за 2018 и 2019 г. промени не са „съществени“ и следователно не изискват оценка. Регулаторът настоява, че оценка е необходима и иска Би Би Си да представи дългосрочна стратегия за трансформиране на услугата iPlayer, вкл. за  ефектите върху всички заинтересовани страни.  Обществената телевизия представя исканата стратегия.

Сега е ред на регулатора да прецени дали  цената на предложената промяна от гледна точка на значението на услугата – и в резултат регулаторът има три опции – положително решение (Би Би Си може да извърши промяната на iPlayer), отрицателно решение или положително решение с условия.

Регулаторът открива обществена консултация.

В методологическо отношение Би  Би Си използва количествен и качествен анализ за проучване както на нагласите на аудиторията, така и икономическите ефекти и влиянието върху конкуренцията.  Съпътстващи анализи, на които се основава стратегията:

В заключение:

Новите и съществено променяните услуги на обществените медии в ЕС трябва да отговарят на мисията на обществените медии и да се финансират – ако отговарят на мисията – адекватно, не повече и не по-малко.

iplayer  е такъв пример, тест се проведе например  и когато Би Би Си 3 премина от наземно към онлайн разпространение.

Сега да се върнем в родината.

Как точно се вземат решенията за нови услуги или съществени промени в съществуващите услуги? На базата на каква точно информация БНТ2  промени лицензията си – и СЕМ разреши промените –  просто защото това е един от последните примери, иначе може да се пита и за други програми и услуги.

Вярно, законът не изисква тест за обществена значимост на услугите. И все пак – изисква се обосновка, защото за тези услуги се разходва обществен ресурс – държавен бюджет.

Идват избори за генерални директори в двете обществени медии – може някой кандидат да запише в концепцията си, че ще работи за съответствие  мисия – бюджет и за модернизиране на правната рамка.

 

2018-05-03 python, multiprocessing, thread-ове и забивания

Post Syndicated from Vasil Kolev original https://vasil.ludost.net/blog/?p=3384

Всеки ден се убеждавам, че нищо не работи.

Открих забавен проблем с python и multiprocessing, който в момента още не мога да реша чий проблем е (в крайна сметка ще се окаже мой). Отне ми прилично количество време да го хвана и си струва да го разкажа.

Малко предистория: ползваме influxdb, в което тъпчем бая секундни данни, които после предъвкваме до минутни. InfluxDB има continuous queries, които вършат тази работа – на някакъв интервал от време хващат новите данни и ги сгъват. Тези заявки имаха няколко проблема:
– не се оправят с попълване на стари данни;
– изпълняват се рядко и минутните данни изостават;
– изпълняват се в общи линии в един thread, което кара минутните данни да изостават още повече (в нашия случай преди да ги сменим с около 12 часа).

Хванаха ме дяволите и си написах просто демонче на python, което да събира информация за различните бази какви данни могат да се сгънат, и паралелно да попълва данните. Работи в общи линии по следния начин:
– взима списък с базите данни
– пуска през multiprocessing-а да се събере за всяка база какви заявки трябва да се пуснат, на база на какви measurement-и има и докога са минутните и секундните данни в тях;
– пуска през multiprocessing-а събраните от предния pass заявки
– и така до края на света (или докато зависне).

След като навакса за няколко часа, успяваше да държи минутните данни в рамките на няколко минути от последните секундни данни, което си беше сериозно подобрение на ситуацията. Единственият проблем беше, че от време на време спираше да process-ва и увисваше.

Днес намерих време да го прегледам внимателно какво му се случва. Процесът изглежда като един parent и 5 fork()-нати child-а, като:
Parent-а спи във futex 0x22555a0;
Child 18455 във futex 0x7fdbfa366000;
Child 18546 read
Child 18457 във futex 0x7fdbfa366000
Child 18461 във futex 0x7fdbfa366000
Child 18462 във futex 0x7fdbfa366000
Child 18465 във futex 0x7fdbf908c2c0

Това не беше особено полезно, и се оказа, че стандартния python debugger (pdb) не може да се закача за съществуващи процеси, но за сметка на това gdb с подходящи debug символи може, и може да дава доста полезна информация. По този начин открих, че parent-а чака един child да приключи работата си:


#11 PyEval_EvalFrameEx (
[email protected]=Frame 0x235fb80, for file /usr/lib64/python2.7/multiprocessing/pool.py, line 543, in wait (self== 1525137960000000000 AND time < 1525138107000000000 GROUP BY time(1m), * fill(linear)\' in a read only context, please use a POST request instead', u'level': u'warning'}], u'statement_id': 0}]}, None], _callback=None, _chunksize=1, _number_left=1, _ready=False, _success=True, _cond=<_Condition(_Verbose__verbose=False, _Condition__lock=, acquire=, _Condition__waiters=[], release=) at remote 0x7fdbe0015310>, _job=45499, _cache={45499: < ...>}) a...(truncated), [email protected]=0) at /usr/src/debug/Python-2.7.5/Python/ceval.c:3040

Като в pool.py около ред 543 има следното:


class ApplyResult(object):

...

def wait(self, timeout=None):
self._cond.acquire()
try:
if not self._ready:
self._cond.wait(timeout)
finally:
self._cond.release()

Първоначално си мислех, че 18546 очаква да прочете нещо от грешното място, но излезе, че това е child-а, който е спечелил състезанието за изпълняване на следващата задача и чака да му я дадат (което изглежда се раздава през futex 0x7fdbfa366000). Един от child-овете обаче чака в друг lock:


(gdb) bt
#0 __lll_lock_wait () at ../nptl/sysdeps/unix/sysv/linux/x86_64/lowlevellock.S:135
#1 0x00007fdbf9b68dcb in _L_lock_812 () from /lib64/libpthread.so.0
#2 0x00007fdbf9b68c98 in __GI___pthread_mutex_lock ([email protected]=0x7fdbf908c2c0 ) at ../nptl/pthread_mutex_lock.c:79
#3 0x00007fdbf8e846ea in _nss_files_gethostbyname4_r ([email protected]=0x233fa44 "localhost", [email protected]=0x7fdbecfcb8e0, [email protected]=0x7fdbecfcb340 "hZ \372\333\177",
[email protected]=1064, [email protected]=0x7fdbecfcb8b0, [email protected]=0x7fdbecfcb910, [email protected]=0x0) at nss_files/files-hosts.c:381
#4 0x00007fdbf9170ed8 in gaih_inet (name=, [email protected]=0x233fa44 "localhost", service=, [email protected]=0x7fdbecfcbb90, [email protected]=0x7fdbecfcb9f0,
[email protected]=0x7fdbecfcb9e0) at ../sysdeps/posix/getaddrinfo.c:877
#5 0x00007fdbf91745cd in __GI_getaddrinfo ([email protected]=0x233fa44 "localhost", [email protected]=0x7fdbecfcbbc0 "8086", [email protected]=0x7fdbecfcbb90, [email protected]=0x7fdbecfcbb78)
at ../sysdeps/posix/getaddrinfo.c:2431
#6 0x00007fdbeed8760d in socket_getaddrinfo (self=
, args=) at /usr/src/debug/Python-2.7.5/Modules/socketmodule.c:4193
#7 0x00007fdbf9e5fbb0 in call_function (oparg=
, pp_stack=0x7fdbecfcbd10) at /usr/src/debug/Python-2.7.5/Python/ceval.c:4408
#8 PyEval_EvalFrameEx (
[email protected]=Frame 0x7fdbe8013350, for file /usr/lib/python2.7/site-packages/urllib3/util/connection.py, line 64, in create_connection (address=('localhost', 8086), timeout=3000, source_address=None, socket_options=[(6, 1, 1)], host='localhost', port=8086, err=None), [email protected]=0) at /usr/src/debug/Python-2.7.5/Python/ceval.c:3040

(gdb) frame 3
#3 0x00007fdbf8e846ea in _nss_files_gethostbyname4_r ([email protected]=0x233fa44 "localhost", [email protected]=0x7fdbecfcb8e0, [email protected]=0x7fdbecfcb340 "hZ \372\333\177",
[email protected]=1064, [email protected]=0x7fdbecfcb8b0, [email protected]=0x7fdbecfcb910, [email protected]=0x0) at nss_files/files-hosts.c:381
381 __libc_lock_lock (lock);
(gdb) list
376 enum nss_status
377 _nss_files_gethostbyname4_r (const char *name, struct gaih_addrtuple **pat,
378 char *buffer, size_t buflen, int *errnop,
379 int *herrnop, int32_t *ttlp)
380 {
381 __libc_lock_lock (lock);
382
383 /* Reset file pointer to beginning or open file. */
384 enum nss_status status = internal_setent (keep_stream);
385

Или в превод – опитваме се да вземем стандартния lock, който libc-то използва за да си пази reentrant функциите, и някой го държи. Кой ли?


(gdb) p lock
$3 = {__data = {__lock = 2, __count = 0, __owner = 16609, __nusers = 1, __kind = 0, __spins = 0, __elision = 0, __list = {__prev = 0x0, __next = 0x0}},
__size = "\002\000\000\000\000\000\000\000\[email protected]\000\000\001", '\000' , __align = 2}
(gdb) p &lock
$4 = (__libc_lock_t *) 0x7fdbf908c2c0

Тук се вижда как owner-а на lock-а всъщност е parent-а. Той обаче не смята, че го държи:


(gdb) p lock
$2 = 0
(gdb) p &lock
$3 = (__libc_lock_t *) 0x7fdbf9450df0
(gdb) x/20x 0x7fdbf9450df0
0x7fdbf9450df0
: 0x00000000 0x00000000 0x00000000 0x00000000
0x7fdbf9450e00 <__abort_msg>: 0x00000000 0x00000000 0x00000000 0x00000000
0x7fdbf9450e10 : 0x00000000 0x00000000 0x00000000 0x00000000
0x7fdbf9450e20 : 0x00000000 0x00000000 0x00000000 0x00000000
0x7fdbf9450e30 : 0x001762c9 0x00000000 0x00000000 0x00000000

… което е и съвсем очаквано, при условие, че са два процеса и тая памет не е обща.

Та, явно това, което се е случило е, че докато parent-а е правел fork(), тоя lock го е държал някой, и child-а реално не може да пипне каквото и да е, свързано с него (което значи никакви reentrant функции в glibc-то, каквито па всички ползват (и би трябвало да ползват)). Въпросът е, че по принцип това не би трябвало да е възможно, щото около fork() няма нищо, което да взима тоя lock, и би трябвало glibc да си освобождава lock-а като излиза от функциите си.

Първоначалното ми идиотско предположение беше, че в signal handler-а на SIGCHLD multiprocessing модула създава новите child-ове, и така докато нещо друго държи lock-а идва сигнал, прави се нов процес и той го “наследява” заключен. Това беше твърде глупаво, за да е истина, и се оказа, че не е…

Около въпросите с lock-а бях стигнал с търсене до две неща – issue 127 в gperftools и Debian bug 657835. Първото каза, че проблемът ми може да е от друг lock, който някой друг държи преди fork-а (което ме накара да се загледам по-внимателно какви lock-ове се държат), а второто, че като цяло ако fork-ваш thread-нато приложение, може после единствено да правиш execve(), защото всичко друго не е ясно колко ще работи.

И накрая се оказа, че ако се ползва multiprocessing модула, той пуска в главния процес няколко thread-а, които да се занимават със следенето и пускането на child-ове за обработка. Та ето какво реално се случва:

– някой child си изработва нужния брой операции и излиза
– parent-а получава SIGCHLD и си отбелязва, че трябва да види какво става
– главния thread на parent-а тръгва да събира списъка бази, и вика в някакъв момент _nss_files_gethostbyname4_r, който взима lock-а;
– по това време другия thread казва “а, нямам достатъчно child-ове, fork()”
– profit.

Текущото ми глупаво решение е да не правя нищо в главния thread, което може да взима тоя lock и да се надявам, че няма още някой такъв. Бъдещото ми решение е или да го пиша на python3 с някой друг модул по темата, или на go (което ще трябва да науча).

Continued: the answers to your questions for Eben Upton

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/eben-q-a-2/

Last week, we shared the first half of our Q&A with Raspberry Pi Trading CEO and Raspberry Pi creator Eben Upton. Today we follow up with all your other questions, including your expectations for a Raspberry Pi 4, Eben’s dream add-ons, and whether we really could go smaller than the Zero.

Live Q&A with Eben Upton, creator of the Raspberry Pi

Get your questions to us now using #AskRaspberryPi on Twitter

With internet security becoming more necessary, will there be automated versions of VPN on an SD card?

There are already third-party tools which turn your Raspberry Pi into a VPN endpoint. Would we do it ourselves? Like the power button, it’s one of those cases where there are a million things we could do and so it’s more efficient to let the community get on with it.

Just to give a counterexample, while we don’t generally invest in optimising for particular use cases, we did invest a bunch of money into optimising Kodi to run well on Raspberry Pi, because we found that very large numbers of people were using it. So, if we find that we get half a million people a year using a Raspberry Pi as a VPN endpoint, then we’ll probably invest money into optimising it and feature it on the website as we’ve done with Kodi. But I don’t think we’re there today.

Have you ever seen any Pis running and doing important jobs in the wild, and if so, how does it feel?

It’s amazing how often you see them driving displays, for example in radio and TV studios. Of course, it feels great. There’s something wonderful about the geographic spread as well. The Raspberry Pi desktop is quite distinctive, both in its previous incarnation with the grey background and logo, and the current one where we have Greg Annandale’s road picture.

The PIXEL desktop on Raspberry Pi

And so it’s funny when you see it in places. Somebody sent me a video of them teaching in a classroom in rural Pakistan and in the background was Greg’s picture.

Raspberry Pi 4!?!

There will be a Raspberry Pi 4, obviously. We get asked about it a lot. I’m sticking to the guidance that I gave people that they shouldn’t expect to see a Raspberry Pi 4 this year. To some extent, the opportunity to do the 3B+ was a surprise: we were surprised that we’ve been able to get 200MHz more clock speed, triple the wireless and wired throughput, and better thermals, and still stick to the $35 price point.

We’re up against the wall from a silicon perspective; we’re at the end of what you can do with the 40nm process. It’s not that you couldn’t clock the processor faster, or put a larger processor which can execute more instructions per clock in there, it’s simply about the energy consumption and the fact that you can’t dissipate the heat. So we’ve got to go to a smaller process node and that’s an order of magnitude more challenging from an engineering perspective. There’s more effort, more risk, more cost, and all of those things are challenging.

With 3B+ out of the way, we’re going to start looking at this now. For the first six months or so we’re going to be figuring out exactly what people want from a Raspberry Pi 4. We’re listening to people’s comments about what they’d like to see in a new Raspberry Pi, and I’m hoping by early autumn we should have an idea of what we want to put in it and a strategy for how we might achieve that.

Could you go smaller than the Zero?

The challenge with Zero as that we’re periphery-limited. If you run your hand around the unit, there is no edge of that board that doesn’t have something there. So the question is: “If you want to go smaller than Zero, what feature are you willing to throw out?”

It’s a single-sided board, so you could certainly halve the PCB area if you fold the circuitry and use both sides, though you’d have to lose something. You could give up some GPIO and go back to 26 pins like the first Raspberry Pi. You could give up the camera connector, you could go to micro HDMI from mini HDMI. You could remove the SD card and just do USB boot. I’m inventing a product live on air! But really, you could get down to two thirds and lose a bunch of GPIO – it’s hard to imagine you could get to half the size.

What’s the one feature that you wish you could outfit on the Raspberry Pi that isn’t cost effective at this time? Your dream feature.

Well, more memory. There are obviously technical reasons why we don’t have more memory on there, but there are also market reasons. People ask “why doesn’t the Raspberry Pi have more memory?”, and my response is typically “go and Google ‘DRAM price’”. We’re used to the price of memory going down. And currently, we’re going through a phase where this has turned around and memory is getting more expensive again.

Machine learning would be interesting. There are machine learning accelerators which would be interesting to put on a piece of hardware. But again, they are not going to be used by everyone, so according to our method of pricing what we might add to a board, machine learning gets treated like a $50 chip. But that would be lovely to do.

Which citizen science projects using the Pi have most caught your attention?

I like the wildlife camera projects. We live out in the countryside in a little village, and we’re conscious of being surrounded by nature but we don’t see a lot of it on a day-to-day basis. So I like the nature cam projects, though, to my everlasting shame, I haven’t set one up yet. There’s a range of them, from very professional products to people taking a Raspberry Pi and a camera and putting them in a plastic box. So those are good fun.

Raspberry Shake seismometer

The Raspberry Shake seismometer

And there’s Meteor Pi from the Cambridge Science Centre, that’s a lot of fun. And the seismometer Raspberry Shake – that sort of thing is really nice. We missed the recent South Wales earthquake; perhaps we should set one up at our Californian office.

How does it feel to go to bed every day knowing you’ve changed the world for the better in such a massive way?

What feels really good is that when we started this in 2006 nobody else was talking about it, but now we’re part of a very broad movement.

We were in a really bad way: we’d seen a collapse in the number of applicants applying to study Computer Science at Cambridge and elsewhere. In our view, this reflected a move away from seeing technology as ‘a thing you do’ to seeing it as a ‘thing that you have done to you’. It is problematic from the point of view of the economy, industry, and academia, but most importantly it damages the life prospects of individual children, particularly those from disadvantaged backgrounds. The great thing about STEM subjects is that you can’t fake being good at them. There are a lot of industries where your Dad can get you a job based on who he knows and then you can kind of muddle along. But if your dad gets you a job building bridges and you suck at it, after the first or second bridge falls down, then you probably aren’t going to be building bridges anymore. So access to STEM education can be a great driver of social mobility.

By the time we were launching the Raspberry Pi in 2012, there was this wonderful movement going on. Code Club, for example, and CoderDojo came along. Lots of different ways of trying to solve the same problem. What feels really, really good is that we’ve been able to do this as part of an enormous community. And some parts of that community became part of the Raspberry Pi Foundation – we merged with Code Club, we merged with CoderDojo, and we continue to work alongside a lot of these other organisations. So in the two seconds it takes me to fall asleep after my face hits the pillow, that’s what I think about.

We’re currently advertising a Programme Manager role in New Delhi, India. Did you ever think that Raspberry Pi would be advertising a role like this when you were bringing together the Foundation?

No, I didn’t.

But if you told me we were going to be hiring somewhere, India probably would have been top of my list because there’s a massive IT industry in India. When we think about our interaction with emerging markets, India, in a lot of ways, is the poster child for how we would like it to work. There have already been some wonderful deployments of Raspberry Pi, for example in Kerala, without our direct involvement. And we think we’ve got something that’s useful for the Indian market. We have a product, we have clubs, we have teacher training. And we have a body of experience in how to teach people, so we have a physical commercial product as well as a charitable offering that we think are a good fit.

It’s going to be massive.

What is your favourite BBC type-in listing?

There was a game called Codename: Druid. There is a famous game called Codename: Droid which was the sequel to Stryker’s Run, which was an awesome, awesome game. And there was a type-in game called Codename: Druid, which was at the bottom end of what you would consider a commercial game.

codename druid

And I remember typing that in. And what was really cool about it was that the next month, the guy who wrote it did another article that talks about the memory map and which operating system functions used which bits of memory. So if you weren’t going to do disc access, which bits of memory could you trample on and know the operating system would survive.

babbage versus bugs Raspberry Pi annual

See the full listing for Babbage versus Bugs in the Raspberry Pi 2018 Annual

I still like type-in listings. The Raspberry Pi 2018 Annual has a type-in listing that I wrote for a Babbage versus Bugs game. I will say that’s not the last type-in listing you will see from me in the next twelve months. And if you download the PDF, you could probably copy and paste it into your favourite text editor to save yourself some time.

The post Continued: the answers to your questions for Eben Upton appeared first on Raspberry Pi.

Community profile: Dave Akerman

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/community-profile-dave-akerman/

This column is from The MagPi issue 61. You can download a PDF of the full issue for free, or subscribe to receive the print edition through your letterbox or the digital edition on your tablet. All proceeds from the print and digital editions help the Raspberry Pi Foundation achieve our charitable goals.

The pinned tweet on Dave Akerman’s Twitter account shows a table displaying the various components needed for a high-altitude balloon (HAB) flight. Batteries, leads, a camera and Raspberry Pi, plus an unusually themed payload. The caption reads ‘The Queen, The Duke of York, and my TARDIS”, and sums up Dave’s maker career in a heartbeat.

David Akerman on Twitter

The Queen, The Duke of York, and my TARDIS 🙂 #UKHAS #RaspberryPi

Though writing software for industrial automation pays the bills, the majority of Dave’s time is spent in the world of high-altitude ballooning and the ever-growing community that encompasses it. And, while he makes some money sending business-themed balloons to near space for the likes of Aardman Animations, Confused.com, and the BBC, Dave is best known in the Raspberry Pi community for his use of the small computer in every payload, and his work as a tutor alongside the Foundation’s staff at Skycademy events.

Dave Akerman The MagPi Raspberry Pi Community Profile

Dave continues to help others while breaking records and having a good time exploring the atmosphere.

Dave has dedicated many hours and many, many more miles to assist with the Foundation’s Skycademy programme, helping to explore high-altitude ballooning with educators from across the UK. Using a Raspberry Pi and various other pieces of lightweight tech, Dave and Foundation staff member James Robinson explored the incorporation of high-altitude ballooning into education. Through Skycademy, educators were able to learn new skills and take them to the classroom, setting off their own balloons with their students, and recording the results on Raspberry Pis.

Dave Akerman The MagPi Raspberry Pi Community Profile

Dave’s most recent flight broke a new record. On 13 August 2017, his HAB payload was able to send back the highest images taken by any amateur flight.

But education isn’t the only reason for Dave’s involvement in the HAB community. As with anyone passionate about a specific hobby, Dave strives to break records. The most recent record-breaking flight took place on 13 August 2017, when Dave’s Raspberry Pi Zero HAB sent home the highest images taken by any amateur high-altitude balloon launch: at 43014 metres. No other HAB balloon has provided images from such an altitude, and the lightweight nature of the Pi Zero definitely helped, as Dave went on to mention on Twitter a few days later.

Dave Akerman The MagPi Raspberry Pi Community Profile

Dave is recognised as being the first person to incorporate a Raspberry Pi into a HAB payload, and continues to break records with the help of the little green board. More recently, he’s been able to lighten the load by using the Raspberry Pi Zero.

When the first Pi made its way to near space, Dave tore the computer apart in order to meet the weight restriction. The Pi in the Sky board was created to add the extra features needed for the flight. Since then, the HAT has experienced a few changes.

Dave Akerman The MagPi Raspberry Pi Community Profile

The Pi in the Sky board, created specifically for HAB flights.

Dave first fell in love with high-altitude ballooning after coming across the hobby in a video shared on a photographic forum. With a lifelong interest in space thanks to watching the Moon landings as a boy, plus a talent for electronics and photography, it seems a natural progression for him. Throw in his coding skills from learning to program on a Teletype and it’s no wonder he was ready and eager to take to the skies, so to speak, and capture the curvature of the Earth. What was so great about using the Raspberry Pi was the instant gratification he got from receiving images in real time as they were taken during the flight. While other devices could control a camera and store captured images for later retrieval, thanks to the Pi Dave was able to transmit the files back down to Earth and check the progress of his balloon while attempting to break records with a flight.

Dave Akerman The MagPi Raspberry Pi Community Profile Morph

One of the many commercial flights Dave has organised featured the classic children’s TV character Morph, a creation of the Aardman Animations studio known for Wallace and Gromit. Morph took to the sky twice in his mission to reach near space, and finally succeeded in 2016.

High-altitude ballooning isn’t the only part of Dave’s life that incorporates a Raspberry Pi. Having “lost count” of how many Pis he has running tasks, Dave has also created radio receivers for APRS (ham radio data), ADS-B (aircraft tracking), and OGN (gliders), along with a time-lapse camera in his garden, and he has a few more Pi for tinkering purposes.

The post Community profile: Dave Akerman appeared first on Raspberry Pi.

Engineering deep dive: Encoding of SCTs in certificates

Post Syndicated from Let's Encrypt - Free SSL/TLS Certificates original https://letsencrypt.org/2018/04/04/sct-encoding.html

<p>Let&rsquo;s Encrypt recently <a href="https://community.letsencrypt.org/t/signed-certificate-timestamps-embedded-in-certificates/57187">launched SCT embedding in
certificates</a>.
This feature allows browsers to check that a certificate was submitted to a
<a href="https://en.wikipedia.org/wiki/Certificate_Transparency">Certificate Transparency</a>
log. As part of the launch, we did a thorough review
that the encoding of Signed Certificate Timestamps (SCTs) in our certificates
matches the relevant specifications. In this post, I&rsquo;ll dive into the details.
You&rsquo;ll learn more about X.509, ASN.1, DER, and TLS encoding, with references to
the relevant RFCs.</p>

<p>Certificate Transparency offers three ways to deliver SCTs to a browser: In a
TLS extension, in stapled OCSP, or embedded in a certificate. We chose to
implement the embedding method because it would just work for Let&rsquo;s Encrypt
subscribers without additional work. In the SCT embedding method, we submit
a &ldquo;precertificate&rdquo; with a <a href="#poison">poison extension</a> to a set of
CT logs, and get back SCTs. We then issue a real certificate based on the
precertificate, with two changes: The poison extension is removed, and the SCTs
obtained earlier are added in another extension.</p>

<p>Given a certificate, let&rsquo;s first look for the SCT list extension. According to CT (<a href="https://tools.ietf.org/html/rfc6962#section-3.3">RFC 6962
section 3.3</a>),
the extension OID for a list of SCTs is <code>1.3.6.1.4.1.11129.2.4.2</code>. An <a href="http://www.hl7.org/Oid/information.cfm">OID (object
ID)</a> is a series of integers, hierarchically
assigned and globally unique. They are used extensively in X.509, for instance
to uniquely identify extensions.</p>

<p>We can <a href="https://acme-v01.api.letsencrypt.org/acme/cert/031f2484307c9bc511b3123cb236a480d451">download an example certificate</a>,
and view it using OpenSSL (if your OpenSSL is old, it may not display the
detailed information):</p>

<pre><code>$ openssl x509 -noout -text -inform der -in Downloads/031f2484307c9bc511b3123cb236a480d451

CT Precertificate SCTs:
Signed Certificate Timestamp:
Version : v1(0)
Log ID : DB:74:AF:EE:CB:29:EC:B1:FE:CA:3E:71:6D:2C:E5:B9:
AA:BB:36:F7:84:71:83:C7:5D:9D:4F:37:B6:1F:BF:64
Timestamp : Mar 29 18:45:07.993 2018 GMT
Extensions: none
Signature : ecdsa-with-SHA256
30:44:02:20:7E:1F:CD:1E:9A:2B:D2:A5:0A:0C:81:E7:
13:03:3A:07:62:34:0D:A8:F9:1E:F2:7A:48:B3:81:76:
40:15:9C:D3:02:20:65:9F:E9:F1:D8:80:E2:E8:F6:B3:
25:BE:9F:18:95:6D:17:C6:CA:8A:6F:2B:12:CB:0F:55:
FB:70:F7:59:A4:19
Signed Certificate Timestamp:
Version : v1(0)
Log ID : 29:3C:51:96:54:C8:39:65:BA:AA:50:FC:58:07:D4:B7:
6F:BF:58:7A:29:72:DC:A4:C3:0C:F4:E5:45:47:F4:78
Timestamp : Mar 29 18:45:08.010 2018 GMT
Extensions: none
Signature : ecdsa-with-SHA256
30:46:02:21:00:AB:72:F1:E4:D6:22:3E:F8:7F:C6:84:
91:C2:08:D2:9D:4D:57:EB:F4:75:88:BB:75:44:D3:2F:
95:37:E2:CE:C1:02:21:00:8A:FF:C4:0C:C6:C4:E3:B2:
45:78:DA:DE:4F:81:5E:CB:CE:2D:57:A5:79:34:21:19:
A1:E6:5B:C7:E5:E6:9C:E2
</code></pre>

<p>Now let&rsquo;s go a little deeper. How is that extension represented in
the certificate? Certificates are expressed in
<a href="https://en.wikipedia.org/wiki/Abstract_Syntax_Notation_One">ASN.1</a>,
which generally refers to both a language for expressing data structures
and a set of formats for encoding them. The most common format,
<a href="https://en.wikipedia.org/wiki/X.690#DER_encoding">DER</a>,
is a tag-length-value format. That is, to encode an object, first you write
down a tag representing its type (usually one byte), then you write
down a number expressing how long the object is, then you write down
the object contents. This is recursive: An object can contain multiple
objects within it, each of which has its own tag, length, and value.</p>

<p>One of the cool things about DER and other tag-length-value formats is that you
can decode them to some degree without knowing what they mean. For instance, I
can tell you that 0x30 means the data type &ldquo;SEQUENCE&rdquo; (a struct, in ASN.1
terms), and 0x02 means &ldquo;INTEGER&rdquo;, then give you this hex byte sequence to
decode:</p>

<pre><code>30 06 02 01 03 02 01 0A
</code></pre>

<p>You could tell me right away that decodes to:</p>

<pre><code>SEQUENCE
INTEGER 3
INTEGER 10
</code></pre>

<p>Try it yourself with this great <a href="https://lapo.it/asn1js/#300602010302010A">JavaScript ASN.1
decoder</a>. However, you wouldn&rsquo;t know
what those integers represent without the corresponding ASN.1 schema (or
&ldquo;module&rdquo;). For instance, if you knew that this was a piece of DogData, and the
schema was:</p>

<pre><code>DogData ::= SEQUENCE {
legs INTEGER,
cutenessLevel INTEGER
}
</code></pre>

<p>You&rsquo;d know this referred to a three-legged dog with a cuteness level of 10.</p>

<p>We can take some of this knowledge and apply it to our certificates. As a first
step, convert the above certificate to hex with
<code>xxd -ps &lt; Downloads/031f2484307c9bc511b3123cb236a480d451</code>. You can then copy
and paste the result into
<a href="https://lapo.it/asn1js">lapo.it/asn1js</a> (or use <a href="https://lapo.it/asn1js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this handy link</a>). You can also run <code>openssl asn1parse -i -inform der -in Downloads/031f2484307c9bc511b3123cb236a480d451</code> to use OpenSSL&rsquo;s parser, which is less easy to use in some ways, but easier to copy and paste.</p>

<p>In the decoded data, we can find the OID <code>1.3.6.1.4.1.11129.2.4.2</code>, indicating
the SCT list extension. Per <a href="https://tools.ietf.org/html/rfc5280#page-17">RFC 5280, section
4.1</a>, an extension is defined:</p>

<pre><code>Extension ::= SEQUENCE {
extnID OBJECT IDENTIFIER,
critical BOOLEAN DEFAULT FALSE,
extnValue OCTET STRING
— contains the DER encoding of an ASN.1 value
— corresponding to the extension type identified
— by extnID
}
</code></pre>

<p>We&rsquo;ve found the <code>extnID</code>. The &ldquo;critical&rdquo; field is omitted because it has the
default value (false). Next up is the <code>extnValue</code>. This has the type
<code>OCTET STRING</code>, which has the tag &ldquo;0x04&rdquo;. <code>OCTET STRING</code> means &ldquo;here&rsquo;s
a bunch of bytes!&rdquo; In this case, as described by the spec, those bytes
happen to contain more DER. This is a fairly common pattern in X.509
to deal with parameterized data. For instance, this allows defining a
structure for extensions without knowing ahead of time all the structures
that a future extension might want to carry in its value. If you&rsquo;re a C
programmer, think of it as a <code>void*</code> for data structures. If you prefer Go,
think of it as an <code>interface{}</code>.</p>

<p>Here&rsquo;s that <code>extnValue</code>:</p>

<pre><code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
</code></pre>

<p>That&rsquo;s tag &ldquo;0x04&rdquo;, meaning <code>OCTET STRING</code>, followed by &ldquo;0x81 0xF5&rdquo;, meaning
&ldquo;this string is 245 bytes long&rdquo; (the 0x81 prefix is part of <a href="#variable-length">variable length
number encoding</a>).</p>

<p>According to <a href="https://tools.ietf.org/html/rfc6962#section-3.3">RFC 6962, section
3.3</a>, &ldquo;obtained SCTs
can be directly embedded in the final certificate, by encoding the
SignedCertificateTimestampList structure as an ASN.1 <code>OCTET STRING</code>
and inserting the resulting data in the TBSCertificate as an X.509v3
certificate extension&rdquo;</p>

<p>So, we have an <code>OCTET STRING</code>, all&rsquo;s good, right? Except if you remove the
tag and length from extnValue to get its value, you&rsquo;re left with:</p>

<pre><code>04 81 F2 00F0007500DB74AFEEC…
</code></pre>

<p>There&rsquo;s that &ldquo;0x04&rdquo; tag again, but with a shorter length. Why
do we nest one <code>OCTET STRING</code> inside another? It&rsquo;s because the
contents of extnValue are required by RFC 5280 to be valid DER, but a
SignedCertificateTimestampList is not encoded using DER (more on that
in a minute). So, by RFC 6962, a SignedCertificateTimestampList is wrapped in an
<code>OCTET STRING</code>, which is wrapped in another <code>OCTET STRING</code> (the extnValue).</p>

<p>Once we decode that second <code>OCTET STRING</code>, we&rsquo;re left with the contents:</p>

<pre><code>00F0007500DB74AFEEC…
</code></pre>

<p>&ldquo;0x00&rdquo; isn&rsquo;t a valid tag in DER. What is this? It&rsquo;s TLS encoding. This is
defined in <a href="https://tools.ietf.org/html/rfc5246#section-4">RFC 5246, section 4</a>
(the TLS 1.2 RFC). TLS encoding, like ASN.1, has both a way to define data
structures and a way to encode those structures. TLS encoding differs
from DER in that there are no tags, and lengths are only encoded when necessary for
variable-length arrays. Within an encoded structure, the type of a field is determined by
its position, rather than by a tag. This means that TLS-encoded structures are
more compact than DER structures, but also that they can&rsquo;t be processed without
knowing the corresponding schema. For instance, here&rsquo;s the top-level schema from
<a href="https://tools.ietf.org/html/rfc6962#section-3.3">RFC 6962, section 3.3</a>:</p>

<pre><code> The contents of the ASN.1 OCTET STRING embedded in an OCSP extension
or X509v3 certificate extension are as follows:

opaque SerializedSCT&lt;1..2^16-1&gt;;

struct {
SerializedSCT sct_list &lt;1..2^16-1&gt;;
} SignedCertificateTimestampList;

Here, &quot;SerializedSCT&quot; is an opaque byte string that contains the
serialized TLS structure.
</code></pre>

<p>Right away, we&rsquo;ve found one of those variable-length arrays. The length of such
an array (in bytes) is always represented by a length field just big enough to
hold the max array size. The max size of an <code>sct_list</code> is 65535 bytes, so the
length field is two bytes wide. Sure enough, those first two bytes are &ldquo;0x00
0xF0&rdquo;, or 240 in decimal. In other words, this <code>sct_list</code> will have 240 bytes. We
don&rsquo;t yet know how many SCTs will be in it. That will become clear only by
continuing to parse the encoded data and seeing where each struct ends (spoiler
alert: there are two SCTs!).</p>

<p>Now we know the first SerializedSCT starts with <code>0075…</code>. SerializedSCT
is itself a variable-length field, this time containing <code>opaque</code> bytes (much like <code>OCTET STRING</code>
back in the ASN.1 world). Like SignedCertificateTimestampList, it has a max size
of 65535 bytes, so we pull off the first two bytes and discover that the first
SerializedSCT is 0x0075 (117 decimal) bytes long. Here&rsquo;s the whole thing, in
hex:</p>

<pre><code>00DB74AFEECB29ECB1FECA3E716D2CE5B9AABB36F7847183C75D9D4F37B61FBF64000001627313EB19000004030046304402207E1FCD1E9A2BD2A50A0C81E713033A0762340DA8F91EF27A48B3817640159CD30220659FE9F1D880E2E8F6B325BE9F18956D17C6CA8A6F2B12CB0F55FB70F759A419
</code></pre>

<p>This can be decoded using the TLS encoding struct defined in <a href="https://tools.ietf.org/html/rfc6962#page-13">RFC 6962, section
3.2</a>:</p>

<pre><code>enum { v1(0), (255) }
Version;

struct {
opaque key_id[32];
} LogID;

opaque CtExtensions&lt;0..2^16-1&gt;;

struct {
Version sct_version;
LogID id;
uint64 timestamp;
CtExtensions extensions;
digitally-signed struct {
Version sct_version;
SignatureType signature_type = certificate_timestamp;
uint64 timestamp;
LogEntryType entry_type;
select(entry_type) {
case x509_entry: ASN.1Cert;
case precert_entry: PreCert;
} signed_entry;
CtExtensions extensions;
};
} SignedCertificateTimestamp;
</code></pre>

<p>Breaking that down:</p>

<pre><code># Version sct_version v1(0)
00
# LogID id (aka opaque key_id[32])
DB74AFEECB29ECB1FECA3E716D2CE5B9AABB36F7847183C75D9D4F37B61FBF64
# uint64 timestamp (milliseconds since the epoch)
000001627313EB19
# CtExtensions extensions (zero-length array)
0000
# digitally-signed struct
04030046304402207E1FCD1E9A2BD2A50A0C81E713033A0762340DA8F91EF27A48B3817640159CD30220659FE9F1D880E2E8F6B325BE9F18956D17C6CA8A6F2B12CB0F55FB70F759A419
</code></pre>

<p>To understand the &ldquo;digitally-signed struct,&rdquo; we need to turn back to <a href="https://tools.ietf.org/html/rfc5246#section-4.7">RFC 5246,
section 4.7</a>. It says:</p>

<pre><code>A digitally-signed element is encoded as a struct DigitallySigned:

struct {
SignatureAndHashAlgorithm algorithm;
opaque signature&lt;0..2^16-1&gt;;
} DigitallySigned;
</code></pre>

<p>And in <a href="https://tools.ietf.org/html/rfc5246#section-7.4.1.4.1">section
7.4.1.4.1</a>:</p>

<pre><code>enum {
none(0), md5(1), sha1(2), sha224(3), sha256(4), sha384(5),
sha512(6), (255)
} HashAlgorithm;

enum { anonymous(0), rsa(1), dsa(2), ecdsa(3), (255) }
SignatureAlgorithm;

struct {
HashAlgorithm hash;
SignatureAlgorithm signature;
} SignatureAndHashAlgorithm;
</code></pre>

<p>We have &ldquo;0x0403&rdquo;, which corresponds to sha256(4) and ecdsa(3). The next two
bytes, &ldquo;0x0046&rdquo;, tell us the length of the &ldquo;opaque signature&rdquo; field, 70 bytes in
decimal. To decode the signature, we reference <a href="https://tools.ietf.org/html/rfc4492#page-20">RFC 4492 section
5.4</a>, which says:</p>

<pre><code>The digitally-signed element is encoded as an opaque vector &lt;0..2^16-1&gt;, the
contents of which are the DER encoding corresponding to the
following ASN.1 notation.

Ecdsa-Sig-Value ::= SEQUENCE {
r INTEGER,
s INTEGER
}
</code></pre>

<p>Having dived through two layers of TLS encoding, we are now back in ASN.1 land!
We
<a href="https://lapo.it/asn1js/#304402207E1FCD1E9A2BD2A50A0C81E713033A0762340DA8F91EF27A48B3817640159CD30220659FE9F1D880E2E8F6B325BE9F18956D17C6CA8A6F2B12CB0F55FB70F759A419">decode</a>
the remaining bytes into a SEQUENCE containing two INTEGERS. And we&rsquo;re done! Here&rsquo;s the whole
extension decoded:</p>

<pre><code># Extension SEQUENCE – RFC 5280
30
# length 0x0104 bytes (260 decimal)
820104
# OBJECT IDENTIFIER
06
# length 0x0A bytes (10 decimal)
0A
# value (1.3.6.1.4.1.11129.2.4.2)
2B06010401D679020402
# OCTET STRING
04
# length 0xF5 bytes (245 decimal)
81F5
# OCTET STRING (embedded) – RFC 6962
04
# length 0xF2 bytes (242 decimal)
81F2
# Beginning of TLS encoded SignedCertificateTimestampList – RFC 5246 / 6962
# length 0xF0 bytes
00F0
# opaque SerializedSCT&lt;1..2^16-1&gt;
# length 0x75 bytes
0075
# Version sct_version v1(0)
00
# LogID id (aka opaque key_id[32])
DB74AFEECB29ECB1FECA3E716D2CE5B9AABB36F7847183C75D9D4F37B61FBF64
# uint64 timestamp (milliseconds since the epoch)
000001627313EB19
# CtExtensions extensions (zero-length array)
0000
# digitally-signed struct – RFC 5426
# SignatureAndHashAlgorithm (ecdsa-sha256)
0403
# opaque signature&lt;0..2^16-1&gt;;
# length 0x0046
0046
# DER-encoded Ecdsa-Sig-Value – RFC 4492
30 # SEQUENCE
44 # length 0x44 bytes
02 # r INTEGER
20 # length 0x20 bytes
# value
7E1FCD1E9A2BD2A50A0C81E713033A0762340DA8F91EF27A48B3817640159CD3
02 # s INTEGER
20 # length 0x20 bytes
# value
659FE9F1D880E2E8F6B325BE9F18956D17C6CA8A6F2B12CB0F55FB70F759A419
# opaque SerializedSCT&lt;1..2^16-1&gt;
# length 0x77 bytes
0077
# Version sct_version v1(0)
00
# LogID id (aka opaque key_id[32])
293C519654C83965BAAA50FC5807D4B76FBF587A2972DCA4C30CF4E54547F478
# uint64 timestamp (milliseconds since the epoch)
000001627313EB2A
# CtExtensions extensions (zero-length array)
0000
# digitally-signed struct – RFC 5426
# SignatureAndHashAlgorithm (ecdsa-sha256)
0403
# opaque signature&lt;0..2^16-1&gt;;
# length 0x0048
0048
# DER-encoded Ecdsa-Sig-Value – RFC 4492
30 # SEQUENCE
46 # length 0x46 bytes
02 # r INTEGER
21 # length 0x21 bytes
# value
00AB72F1E4D6223EF87FC68491C208D29D4D57EBF47588BB7544D32F9537E2CEC1
02 # s INTEGER
21 # length 0x21 bytes
# value
008AFFC40CC6C4E3B24578DADE4F815ECBCE2D57A579342119A1E65BC7E5E69CE2
</code></pre>

<p>One surprising thing you might notice: In the first SCT, <code>r</code> and <code>s</code> are twenty
bytes long. In the second SCT, they are both twenty-one bytes long, and have a
leading zero. Integers in DER are two&rsquo;s complement, so if the leftmost bit is
set, they are interpreted as negative. Since <code>r</code> and <code>s</code> are positive, if the
leftmost bit would be a 1, an extra byte has to be added so that the leftmost
bit can be 0.</p>

<p>This is a little taste of what goes into encoding a certificate. I hope it was
informative! If you&rsquo;d like to learn more, I recommend &ldquo;<a href="http://luca.ntop.org/Teaching/Appunti/asn1.html">A Layman&rsquo;s Guide to a
Subset of ASN.1, BER, and DER</a>.&rdquo;</p>

<p><a name="poison"></a>Footnote 1: A &ldquo;poison extension&rdquo; is defined by <a href="https://tools.ietf.org/html/rfc6962#section-3.1">RFC 6962
section 3.1</a>:</p>

<pre><code>The Precertificate is constructed from the certificate to be issued by adding a special
critical poison extension (OID `1.3.6.1.4.1.11129.2.4.3`, whose
extnValue OCTET STRING contains ASN.1 NULL data (0x05 0x00))
</code></pre>

<p>In other words, it&rsquo;s an empty extension whose only purpose is to ensure that
certificate processors will not accept precertificates as valid certificates. The
specification ensures this by setting the &ldquo;critical&rdquo; bit on the extension, which
ensures that code that doesn&rsquo;t recognize the extension will reject the whole
certificate. Code that does recognize the extension specifically as poison
will also reject the certificate.</p>

<p><a name="variable-length"></a>Footnote 2: Lengths from 0-127 are represented by
a single byte (short form). To express longer lengths, more bytes are used (long form).
The high bit (0x80) on the first byte is set to distinguish long form from short
form. The remaining bits are used to express how many more bytes to read for the
length. For instance, 0x81F5 means &ldquo;this is long form because the length is
greater than 127, but there&rsquo;s still only one byte of length (0xF5) to decode.&rdquo;</p>

Cabinet of Secret Documents from Australia

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2018/02/cabinet_of_secr.html

This story of leaked Australian government secrets is unlike any other I’ve heard:

It begins at a second-hand shop in Canberra, where ex-government furniture is sold off cheaply.

The deals can be even cheaper when the items in question are two heavy filing cabinets to which no-one can find the keys.

They were purchased for small change and sat unopened for some months until the locks were attacked with a drill.

Inside was the trove of documents now known as The Cabinet Files.

The thousands of pages reveal the inner workings of five separate governments and span nearly a decade.

Nearly all the files are classified, some as “top secret” or “AUSTEO”, which means they are to be seen by Australian eyes only.

Yes, that really happened. The person who bought and opened the file cabinets contacted the Australian Broadcasting Corp, who is now publishing a bunch of it.

There’s lots of interesting (and embarassing) stuff in the documents, although most of it is local politics. I am more interested in the government’s reaction to the incident: they’re pushing for a law making it illegal for the press to publish government secrets it received through unofficial channels.

“The one thing I would point out about the legislation that does concern me particularly is that classified information is an element of the offence,” he said.

“That is to say, if you’ve got a filing cabinet that is full of classified information … that means all the Crown has to prove if they’re prosecuting you is that it is classified ­ nothing else.

“They don’t have to prove that you knew it was classified, so knowledge is beside the point.”

[…]

Many groups have raised concerns, including media organisations who say they unfairly target journalists trying to do their job.

But really anyone could be prosecuted just for possessing classified information, regardless of whether they know about it.

That might include, for instance, if you stumbled across a folder of secret files in a regular skip bin while walking home and handed it over to a journalist.

This illustrates a fundamental misunderstanding of the threat. The Australian Broadcasting Corp gets their funding from the government, and was very restrained in what they published. They waited months before publishing as they coordinated with the Australian government. They allowed the government to secure the files, and then returned them. From the government’s perspective, they were the best possible media outlet to receive this information. If the government makes it illegal for the Australian press to publish this sort of material, the next time it will be sent to the BBC, the Guardian, the New York Times, or Wikileaks. And since people no longer read their news from newspapers sold in stores but on the Internet, the result will be just as many people reading the stories with far fewer redactions.

The proposed law is older than this leak, but the leak is giving it new life. The Australian opposition party is being cagey on whether they will support the law. They don’t want to appear weak on national security, so I’m not optimistic.

EDITED TO ADD (2/8): The Australian government backed down on that new security law.

EDITED TO ADD (2/13): Excellent political cartoon.

Community Profile: Dr. Lucy Rogers

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/community-profile-lucy-rogers/

This column is from The MagPi issue 58. You can download a PDF of the full issue for free, or subscribe to receive the print edition through your letterbox or the digital edition on your tablet. All proceeds from the print and digital editions help the Raspberry Pi Foundation achieve our charitable goals.

Dr Lucy Rogers calls herself a Transformer. “I transform simple electronics into cool gadgets, I transform science into plain English, I transform problems into opportunities. I am also a catalyst. I am interested in everything around me, and can often see ways of putting two ideas from very different fields together into one package. If I cannot do this myself, I connect the people who can.”

Dr Lucy Rogers Raspberry Pi The MagPi Community Profile

Among many other projects, Dr Lucy Rogers currently focuses much of her attention on reducing the damage from space debris

It’s a pretty wide range of interests and skills for sure. But it only takes a brief look at Lucy’s résumé to realise that she means it. When she says she’s interested in everything around her, this interest reaches from electronics to engineering, wearable tech, space, robotics, and robotic dinosaurs. And she can be seen talking about all of these things across various companies’ social media, such as IBM, websites including the Women’s Engineering Society, and books, including her own.

Dr Lucy Rogers Raspberry Pi The MagPi Community Profile

With her bright LED boots, Lucy was one of the wonderful Pi community members invited to join us and HRH The Duke of York at St James’s Palace just over a year ago

When not attending conferences as guest speaker, tinkering with electronics, or creating engaging IoT tutorials, she can be found retrofitting Raspberry Pis into the aforementioned robotic dinosaurs at Blackgang Chine Land of Imagination, writing, and judging battling bots for the BBC’s Robot Wars.

Dr Lucy Rogers Raspberry Pi The MagPi Community Profile

First broadcast in the UK between 1998 and 2004, Robot Wars was revived in 2016 with a new look and new judges, including Dr Lucy Rogers. Competitors battle their home-brew robots, and Lucy, together with the other two judges, awards victories among the carnage of robotic remains

Lucy graduated from Lancaster University with a degree in Mechanical Engineering. After that, she spent seven years at Rolls-Royce Industrial Power Group as a graduate trainee before becoming a chartered engineer and earning her PhD in bubbles.

Bubbles?

“Foam formation in low‑expansion fire-fighting equipment. I investigated the equipment to determine how the bubbles were formed,” she explains. Obviously. Bubbles!

Dr Lucy Rogers Raspberry Pi The MagPi Community Profile

Lucy graduated from the Singularity University Graduate Studies Program in 2011, focusing on how robotics, nanotech, medicine, and various technologies can tackle the challenges facing the world

She then went on to become a fellow of the Royal Astronomical Society (RAS) in 2005 and, later, a fellow of both the Institution of Mechanical Engineers (IMechE) and British Interplanetary Society. As a member of the Association of British Science Writers, Lucy wrote It’s ONLY Rocket Science: an Introduction in Plain English.

Dr Lucy Rogers Raspberry Pi The MagPi Community Profile

In It’s Only Rocket Science: An Introduction in Plain English Lucy explains that ‘hard to understand’ isn’t the same as ‘impossible to understand’, and takes her readers through the journey of building a rocket, leaving Earth, and travelling the cosmos

As a standout member of the industry, and all-round fun person to be around, Lucy has quickly established herself as a valued member of the Pi community.

In 2014, with the help of Neil Ford and Andy Stanford-Clark, Lucy worked with the UK’s oldest amusement park, Blackgang Chine Land of Imagination, on the Isle of Wight, with the aim of updating its animatronic dinosaurs. The original Blackgang Chine dinosaurs had a limited range of behaviour: able to roar, move their heads, and stomp a foot in a somewhat repetitive action.

When she contacted Raspberry Pi back in the November of that same year, the team were working on more creative, varied behaviours, giving each dinosaur a new Raspberry Pi-sized brain. This later evolved into a very successful dino-hacking Raspberry Jam.

Dr Lucy Rogers Raspberry Pi The MagPi Community Profile

Lucy, Neil Ford, and Andy Stanford-Clark used several Raspberry Pis and Node-RED to visualise flows of events when updating the robotic dinosaurs at Blackgang Chine. They went on to create the successful WightPi Raspberry Jam event, where visitors could join in with the unique hacking opportunity.

Given her love for tinkering with tech, and a love for stand-up comedy that can be uncovered via a quick YouTube search, it’s no wonder that Lucy was asked to help judge the first round of the ‘Make us laugh’ Pioneers challenge for Raspberry Pi. Alongside comedian Bec Hill, Code Club UK director Maria Quevedo, and the face of the first challenge, Owen Daughtery, Lucy lent her expertise to help name winners in the various categories of the teens event, and offered her support to future Pioneers.

The post Community Profile: Dr. Lucy Rogers appeared first on Raspberry Pi.

Британският орган по конкуренцията: сделката Fox – Sky не е в обществен интерес поради риск за медийния плурализъм

Post Syndicated from nellyo original https://nellyo.wordpress.com/2018/01/24/murdoch-3/

Когато беше предложено на правителството на ГЕРБ  да въведе оценка на плурализма при допускане на медийните концентрации, първата страница на Труд беше заета от заглавието Държавни юзди за медиите слага кабинетът. И идеята отпадна от програмата.

Вероятно в медиите на Мърдок и другите засегнати издатели и собственици  също е имало кампания срещу контрола за плурализъм – но той е въведен и действа. Според  прессъобщение от 23 януари 2018  конкурентният орган (CMA) в Обединеното кралство е взел решение, според което  поемането на пълния контрол  над Sky от Fox не е в обществен интерес  поради съображения, свързани с медийния плурализъм.  Още информация от сайта на правителството на Обединеното кралство:

Плурализъм

Плурализмът на медиите е централен въпрос за демократичния процес в Обединеното кралство и като такъв е  защитен от закона. CMA  установява, че ако сделката приключи, както е предложено, тя няма да е в обществен  интерес.  Murdoch Family Trust (MFT), който контролира Fox и News Corporation (News Corp), засилвайки контрола си над Sky, би имал твърде голям контрол над доставчиците на новини във Великобритания във всички медийни платформи (телевизия, радио, онлайн и вестници) и следователно твърде голямо влияние върху общественото мнение и политическия дневен ред. Новините на MFT се гледат, четат или слушат от близо една трета от населението на Обединеното кралство и имат  дял от потреблението, който е значително по-голям  от всички останали доставчици на новини, с изключение на BBC и ITN.

Поради контрола си върху News Corp, фамилията Мърдок вече има значително влияние върху общественото мнение и  поемането на пълния контрол  над Sky от Fox ще го укрепи още повече. Въпреки съществуването  и на други медийни услуги, предоставящи новини в Обединеното кралство, CMA временно е установила, че те няма да бъдат достатъчни, за да неутрализират увеличеното влияние на MFT, ако се даде ход на сделката.

Стандарти за електронни медии

В разследването на CMA са разгледани и редица доказателства, за да се разбере дали Fox, Sky и MFT имат истински ангажимент към стандартите на електронните медии в Обединеното кралство. В това отношение се констатира, че Fox, който ще упражнява пълен контрол над Sky, не е вероятно да действа срещу обществения интерес. Като цяло Fox има истински ангажимент към стандартите   в Обединеното кралство. Тук е утвърден доставчик, притежаващ лицензии  повече от 20 години. CMA взе под внимание политиките и процедурите, които Fox  има, за да гарантира, че стандартите   са изпълнени.

Наистина преди 2012 г. имаше сериозни недостатъци в контролирания от МФТ вестник News of the world, който  спазваше закона и медийните стандарти. Но News Corp впоследствие е въвела процеси и процедури за справяне с проблема. CMA  е установила, че оттогава насам  няма опасения за стандартите в пресата на MFT.

Разследването разгледа неотдавнашните твърдения за сексуален тормоз срещу служители на Fox News в САЩ. Макар да са сериозни, CMA смята, че те не са пряко свързани с постигането на стандартите за радио- и телевизионно разпространение в ОК и не поставят под съмнение ангажимента на Fox или MFT към стандартите  за електронни медии в Обединеното кралство.

Ан Ламбер, ръководеща групата за независими разследвания, заявява:

Плурализмът на медиите е централен въпрос за нашия демократичен процес. Много е важно никоя група или индивид да няма твърде голям контрол над нашите медии или прекалено голяма власт, за да може да повлияе на политическата програма.

Ако сливането Fox / Sky продължи съгласно предложението, то ще бъде в противоречие с обществения интерес. Това би довело до факта, че фамилията  Мърдок ще има твърде голям контрол върху доставчиците на новини в Обединеното кралство и твърде голямо влияние върху общественото мнение и политическия дневен ред.

Следващи стъпки

CMA изложи редица потенциални възможности за справяне с тези проблеми, посочени в обявлението за обществени средства за защита.Органът предложи евентуални средства за защита, като взе предвид и обявяването от компанията Fox на 14 декември 2017 г., че е договорила продажбата на някои активи, включително интересите им в Sky, на The Walt Disney Company. Докладът на CMA ще бъде финализиран и предоставен на министъра по въпросите на цифровите технологии, културата, медиите и спорта до 1 май 2018 г.  Той  ще вземе окончателното решение за предложената сделка.

В момента тече триседмичен период на консултации по  констатациите на СМА.

Now Open – Third AWS Availability Zone in London

Post Syndicated from Jeff Barr original https://aws.amazon.com/blogs/aws/now-open-third-aws-availability-zone-in-london/

We expand AWS by picking a geographic area (which we call a Region) and then building multiple, isolated Availability Zones in that area. Each Availability Zone (AZ) has multiple Internet connections and power connections to multiple grids.

Today I am happy to announce that we are opening our 50th AWS Availability Zone, with the addition of a third AZ to the EU (London) Region. This will give you additional flexibility to architect highly scalable, fault-tolerant applications that run across multiple AZs in the UK.

Since launching the EU (London) Region, we have seen an ever-growing set of customers, particularly in the public sector and in regulated industries, use AWS for new and innovative applications. Here are a couple of examples, courtesy of my AWS colleagues in the UK:

Enterprise – Some of the UK’s most respected enterprises are using AWS to transform their businesses, including BBC, BT, Deloitte, and Travis Perkins. Travis Perkins is one of the largest suppliers of building materials in the UK and is implementing the biggest systems and business change in its history, including an all-in migration of its data centers to AWS.

Startups – Cross-border payments company Currencycloud has migrated its entire payments production, and demo platform to AWS resulting in a 30% saving on their infrastructure costs. Clearscore, with plans to disrupting the credit score industry, has also chosen to host their entire platform on AWS. UnderwriteMe is using the EU (London) Region to offer an underwriting platform to their customers as a managed service.

Public Sector -The Met Office chose AWS to support the Met Office Weather App, available for iPhone and Android phones. Since the Met Office Weather App went live in January 2016, it has attracted more than half a million users. Using AWS, the Met Office has been able to increase agility, speed, and scalability while reducing costs. The Driver and Vehicle Licensing Agency (DVLA) is using the EU (London) Region for services such as the Strategic Card Payments platform, which helps the agency achieve PCI DSS compliance.

The AWS EU (London) Region has achieved Public Services Network (PSN) assurance, which provides UK Public Sector customers with an assured infrastructure on which to build UK Public Sector services. In conjunction with AWS’s Standardized Architecture for UK-OFFICIAL, PSN assurance enables UK Public Sector organizations to move their UK-OFFICIAL classified data to the EU (London) Region in a controlled and risk-managed manner.

For a complete list of AWS Regions and Services, visit the AWS Global Infrastructure page. As always, pricing for services in the Region can be found on the detail pages; visit our Cloud Products page to get started.

Jeff;

Why Raspberry Pi isn’t vulnerable to Spectre or Meltdown

Post Syndicated from Eben Upton original https://www.raspberrypi.org/blog/why-raspberry-pi-isnt-vulnerable-to-spectre-or-meltdown/

Over the last couple of days, there has been a lot of discussion about a pair of security vulnerabilities nicknamed Spectre and Meltdown. These affect all modern Intel processors, and (in the case of Spectre) many AMD processors and ARM cores. Spectre allows an attacker to bypass software checks to read data from arbitrary locations in the current address space; Meltdown allows an attacker to read arbitrary data from the operating system kernel’s address space (which should normally be inaccessible to user programs).

Both vulnerabilities exploit performance features (caching and speculative execution) common to many modern processors to leak data via a so-called side-channel attack. Happily, the Raspberry Pi isn’t susceptible to these vulnerabilities, because of the particular ARM cores that we use.

To help us understand why, here’s a little primer on some concepts in modern processor design. We’ll illustrate these concepts using simple programs in Python syntax like this one:

t = a+b
u = c+d
v = e+f
w = v+g
x = h+i
y = j+k

While the processor in your computer doesn’t execute Python directly, the statements here are simple enough that they roughly correspond to a single machine instruction. We’re going to gloss over some details (notably pipelining and register renaming) which are very important to processor designers, but which aren’t necessary to understand how Spectre and Meltdown work.

For a comprehensive description of processor design, and other aspects of modern computer architecture, you can’t do better than Hennessy and Patterson’s classic Computer Architecture: A Quantitative Approach.

What is a scalar processor?

The simplest sort of modern processor executes one instruction per cycle; we call this a scalar processor. Our example above will execute in six cycles on a scalar processor.

Examples of scalar processors include the Intel 486 and the ARM1176 core used in Raspberry Pi 1 and Raspberry Pi Zero.

What is a superscalar processor?

The obvious way to make a scalar processor (or indeed any processor) run faster is to increase its clock speed. However, we soon reach limits of how fast the logic gates inside the processor can be made to run; processor designers therefore quickly began to look for ways to do several things at once.

An in-order superscalar processor examines the incoming stream of instructions and tries execute more than one at once, in one of several “pipes”, subject to dependencies between the instructions. Dependencies are important: you might think that a two-way superscalar processor could just pair up (or dual-issue) the six instructions in our example like this:

t, u = a+b, c+d
v, w = e+f, v+g
x, y = h+i, j+k

But this doesn’t make sense: we have to compute v before we can compute w, so the third and fourth instructions can’t be executed at the same time. Our two-way superscalar processor won’t be able to find anything to pair with the third instruction, so our example will execute in four cycles:

t, u = a+b, c+d
v    = e+f                   # second pipe does nothing here
w, x = v+g, h+i
y    = j+k

Examples of superscalar processors include the Intel Pentium, and the ARM Cortex-A7 and Cortex-A53 cores used in Raspberry Pi 2 and Raspberry Pi 3 respectively. Raspberry Pi 3 has only a 33% higher clock speed than Raspberry Pi 2, but has roughly double the performance: the extra performance is partly a result of Cortex-A53’s ability to dual-issue a broader range of instructions than Cortex-A7.

What is an out-of-order processor?

Going back to our example, we can see that, although we have a dependency between v and w, we have other independent instructions later in the program that we could potentially have used to fill the empty pipe during the second cycle. An out-of-order superscalar processor has the ability to shuffle the order of incoming instructions (again subject to dependencies) in order to keep its pipelines busy.

An out-of-order processor might effectively swap the definitions of w and x in our example like this:

t = a+b
u = c+d
v = e+f
x = h+i
w = v+g
y = j+k

allowing it to execute in three cycles:

t, u = a+b, c+d
v, x = e+f, h+i
w, y = v+g, j+k

Examples of out-of-order processors include the Intel Pentium 2 (and most subsequent Intel and AMD x86 processors), and many recent ARM cores, including Cortex-A9, -A15, -A17, and -A57.

What is speculation?

Reordering sequential instructions is a powerful way to recover more instruction-level parallelism, but as processors become wider (able to triple- or quadruple-issue instructions) it becomes harder to keep all those pipes busy. Modern processors have therefore grown the ability to speculate. Speculative execution lets us issue instructions which might turn out not to be required (because they are branched over): this keeps a pipe busy, and if it turns out that the instruction isn’t executed, we can just throw the result away.

To demonstrate the benefits of speculation, let’s look at another example:

t = a+b
u = t+c
v = u+d
if v:
   w = e+f
   x = w+g
   y = x+h

Now we have dependencies from t to u to v, and from w to x to y, so a two-way out-of-order processor without speculation won’t ever be able to fill its second pipe. It spends three cycles computing t, u, and v, after which it knows whether the body of the if statement will execute, in which case it then spends three cycles computing w, x, and y. Assuming the if (a branch instruction) takes one cycle, our example takes either four cycles (if v turns out to be zero) or seven cycles (if v is non-zero).

Speculation effectively shuffles the program like this:

t = a+b
u = t+c
v = u+d
w_ = e+f
x_ = w_+g
y_ = x_+h
if v:
   w, x, y = w_, x_, y_

so we now have additional instruction level parallelism to keep our pipes busy:

t, w_ = a+b, e+f
u, x_ = t+c, w_+g
v, y_ = u+d, x_+h
if v:
   w, x, y = w_, x_, y_

Cycle counting becomes less well defined in speculative out-of-order processors, but the branch and conditional update of w, x, and y are (approximately) free, so our example executes in (approximately) three cycles.

What is a cache?

In the good old days*, the speed of processors was well matched with the speed of memory access. My BBC Micro, with its 2MHz 6502, could execute an instruction roughly every 2µs (microseconds), and had a memory cycle time of 0.25µs. Over the ensuing 35 years, processors have become very much faster, but memory only modestly so: a single Cortex-A53 in a Raspberry Pi 3 can execute an instruction roughly every 0.5ns (nanoseconds), but can take up to 100ns to access main memory.

At first glance, this sounds like a disaster: every time we access memory, we’ll end up waiting for 100ns to get the result back. In this case, this example:

a = mem[0]
b = mem[1]

would take 200ns.

In practice, programs tend to access memory in relatively predictable ways, exhibiting both temporal locality (if I access a location, I’m likely to access it again soon) and spatial locality (if I access a location, I’m likely to access a nearby location soon). Caching takes advantage of these properties to reduce the average cost of access to memory.

A cache is a small on-chip memory, close to the processor, which stores copies of the contents of recently used locations (and their neighbours), so that they are quickly available on subsequent accesses. With caching, the example above will execute in a little over 100ns:

a = mem[0]    # 100ns delay, copies mem[0:15] into cache
b = mem[1]    # mem[1] is in the cache

From the point of view of Spectre and Meltdown, the important point is that if you can time how long a memory access takes, you can determine whether the address you accessed was in the cache (short time) or not (long time).

What is a side channel?

From Wikipedia:

“… a side-channel attack is any attack based on information gained from the physical implementation of a cryptosystem, rather than brute force or theoretical weaknesses in the algorithms (compare cryptanalysis). For example, timing information, power consumption, electromagnetic leaks or even sound can provide an extra source of information, which can be exploited to break the system.”

Spectre and Meltdown are side-channel attacks which deduce the contents of a memory location which should not normally be accessible by using timing to observe whether another location is present in the cache.

Putting it all together

Now let’s look at how speculation and caching combine to permit the Meltdown attack. Consider the following example, which is a user program that sometimes reads from an illegal (kernel) address:

t = a+b
u = t+c
v = u+d
if v:
   w = kern_mem[address]   # if we get here crash
   x = w&0x100
   y = user_mem[x]

Now our out-of-order two-way superscalar processor shuffles the program like this:

t, w_ = a+b, kern_mem[address]
u, x_ = t+c, w_&0x100
v, y_ = u+d, user_mem[x_]

if v:
   # crash
   w, x, y = w_, x_, y_      # we never get here

Even though the processor always speculatively reads from the kernel address, it must defer the resulting fault until it knows that v was non-zero. On the face of it, this feels safe because either:

  • v is zero, so the result of the illegal read isn’t committed to w
  • v is non-zero, so the program crashes before the read is committed to w

However, suppose we flush our cache before executing the code, and arrange a, b, c, and d so that v is zero. Now, the speculative load in the third cycle:

v, y_ = u+d, user_mem[x_]

will read from either address 0x000 or address 0x100 depending on the eighth bit of the result of the illegal read. Because v is zero, the results of the speculative instructions will be discarded, and execution will continue. If we time a subsequent access to one of those addresses, we can determine which address is in the cache. Congratulations: you’ve just read a single bit from the kernel’s address space!

The real Meltdown exploit is more complex than this, but the principle is the same. Spectre uses a similar approach to subvert software array bounds checks.

Conclusion

Modern processors go to great lengths to preserve the abstraction that they are in-order scalar machines that access memory directly, while in fact using a host of techniques including caching, instruction reordering, and speculation to deliver much higher performance than a simple processor could hope to achieve. Meltdown and Spectre are examples of what happens when we reason about security in the context of that abstraction, and then encounter minor discrepancies between the abstraction and reality.

The lack of speculation in the ARM1176, Cortex-A7, and Cortex-A53 cores used in Raspberry Pi render us immune to attacks of the sort.

* days may not be that old, or that good

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Pioneers winners: only you can save us

Post Syndicated from Erin Brindley original https://www.raspberrypi.org/blog/pioneers-winners-only-you-can-save-us/

She asked for help, and you came to her aid. Pioneers, the winners of the Only you can save us challenge have been picked!

Can you see me? Only YOU can save us!

I need your help. This is a call out for those between 11- and 16-years-old in the UK and Republic of Ireland. Something has gone very, very wrong and only you can save us. I’ve collected together as much information for you as I can. You’ll find it at http://www.raspberrypi.org/pioneers.

The challenge

In August we intercepted an emergency communication from a lonesome survivor. She seemed to be in quite a bit of trouble, and asked all you young people aged 11 to 16 to come up with something to help tackle the oncoming crisis, using whatever technology you had to hand. You had ten weeks to work in teams of two to five with an adult mentor to fulfil your mission.

The judges

We received your world-saving ideas, and our savvy survivor pulled together a ragtag bunch of apocalyptic experts to help us judge which ones would be the winning entries.

Dr Shini Somara

Dr Shini Somara is an advocate for STEM education and a mechanical engineer. She was host of The Health Show and has appeared in documentaries for the BBC, PBS Digital, and Sky. You can check out her work hosting Crash Course Physics on YouTube.

Prof Lewis Dartnell is an astrobiologist and author of the book The Knowledge: How to Rebuild Our World From Scratch.

Emma Stephenson has a background in aeronautical engineering and currently works in the Shell Foundation’s Access to Energy and Sustainable Mobility portfolio.

Currently sifting through the entries with the other judges of #makeyourideas with @raspberrypifoundation @_raspberrypi_

151 Likes, 3 Comments – Shini Somara (@drshinisomara) on Instagram: “Currently sifting through the entries with the other judges of #makeyourideas with…”

The winners

Our survivor is currently putting your entries to good use repairing, rebuilding, and defending her base. Our judges chose the following projects as outstanding examples of world-saving digital making.

Theme winner: Computatron

Raspberry Pioneers 2017 – Nerfus Dislikus Killer Robot

This is our entry to the pioneers ‘Only you can save us’ competition. Our team name is Computatrum. Hope you enjoy!

Are you facing an unknown enemy whose only weakness is Nerf bullets? Then this is the robot for you! We loved the especially apocalyptic feel of the Computatron’s cleverly hacked and repurposed elements. The team even used an old floppy disc mechanism to help fire their bullets!

Technically brilliant: Robot Apocalypse Committee

Pioneers Apocalypse 2017 – RationalPi

Thousands of lines of code… Many sheets of acrylic… A camera, touchscreen and fingerprint scanner… This is our entry into the Raspberry Pi Pioneers2017 ‘Only YOU can Save Us’ theme. When zombies or other survivors break into your base, you want a secure way of storing your crackers.

The Robot Apocalypse Committee is back, and this time they’ve brought cheese! The crew designed a cheese- and cracker-dispensing machine complete with face and fingerprint recognition to ensure those rations last until the next supply drop.

Best explanation: Pi Chasers

Tala – Raspberry Pi Pioneers Project

Hi! We are PiChasers and we entered the Raspberry Pi Pionners challenge last time when the theme was “Make it Outdoors!” but now we’ve been faced with another theme “Apocolypse”. We spent a while thinking of an original thing that would help in an apocolypse and decided upon a ‘text-only phone’ which uses local radio communication rather than cellular.

This text-based communication device encased in a tupperware container could be a lifesaver in a crisis! And luckily, the Pi Chasers produced an excellent video and amazing GitHub repo, ensuring that any and all survivors will be able to build their own in the safety of their base.

Most inspiring journey: Three Musketeers

Pioneers Entry – The Apocalypse

Pioneers Entry Team Name: The Three Musketeers Team Participants: James, Zach and Tom

We all know that zombies are terrible at geometry, and the Three Musketeers used this fact to their advantage when building their zombie security system. We were impressed to see the team working together to overcome the roadblocks they faced along the way.

We appreciate what you’re trying to do: Zombie Trolls

Zombie In The Middle

Uploaded by CDA Bodgers on 2017-12-01.

Playing piggy in the middle with zombies sure is a unique way of saving humankind from total extinction! We loved this project idea, and although the Zombie Trolls had a little trouble with their motors, we’re sure with a little more tinkering this zombie-fooling contraption could save us all.

Most awesome

Our judges also wanted to give a special commendation to the following teams for their equally awesome apocalypse-averting ideas:

  • PiRates, for their multifaceted zombie-proofing defence system and the high production value of their video
  • Byte them Pis, for their beautiful zombie-detecting doormat
  • Unatecxon, for their impressive bunker security system
  • Team Crompton, for their pressure-activated door system
  • Team Ernest, for their adventures in LEGO

The prizes

All our winning teams have secured exclusive digital maker boxes. These are jam-packed with tantalising tech to satisfy all tinkering needs, including:

Our theme winners have also secured themselves a place at Coolest Projects 2018 in Dublin, Ireland!

Thank you to everyone who got involved in this round of Pioneers. Look out for your awesome submission swag arriving in the mail!

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Community Profile: Matthew Timmons-Brown

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/community-profile-matthew-timmons-brown/

This column is from The MagPi issue 57. You can download a PDF of the full issue for free, or subscribe to receive the print edition in your mailbox or the digital edition on your tablet. All proceeds from the print and digital editions help the Raspberry Pi Foundation achieve its charitable goals.

“I first set up my YouTube channel because I noticed a massive lack of video tutorials for the Raspberry Pi,” explains Matthew Timmons-Brown, known to many as The Raspberry Pi Guy. At 18 years old, the Cambridge-based student has more than 60 000 subscribers to his channel, making his account the most successful Raspberry Pi–specific YouTube account to date.

Matthew Timmons-Brown

Matt gives a talk at the Raspberry Pi 5th Birthday weekend event

The Raspberry Pi Guy

If you’ve attended a Raspberry Pi event, there’s a good chance you’ve already met Matt. And if not, you’ll have no doubt come across one or more of his tutorials and builds online. On more than one occasion, his work has featured on the Raspberry Pi blog, with his yearly Raspberry Pi roundup videos being a staple of the birthday celebrations.

Matthew Timmons-Brown

With his website, Matt aimed to collect together “the many strands of The Raspberry Pi Guy” into one, neat, cohesive resource — and it works. From newcomers to the credit card-sized computer to hardened Pi veterans, The Raspberry Pi Guy offers aid and inspiration for many. Looking for a review of the Raspberry Pi Zero W? He’s filmed one. Looking for a step-by-step guide to building a Pi-powered Amazon Alexa? No problem, there’s one of those too.

Make your Raspberry Pi artificially intelligent! – Amazon Alexa Personal Assistant Tutorial

Artificial Intelligence. A hefty topic that has dominated the field since computers were first conceived. What if I told you that you could put an artificial intelligence service on your own $30 computer?! That’s right! In this tutorial I will show you how to create your own artificially intelligent personal assistant, using Amazon’s Alexa voice recognition and information service!

Raspberry Pi electric skateboard

Last summer, Matt introduced the world to his Raspberry Pi-controlled electric skateboard, soon finding himself plastered over local press as well as the BBC and tech sites like Adafruit and geek.com. And there’s no question as to why the build was so popular. With YouTubers such as Casey Neistat increasing the demand for electric skateboards on a near-daily basis, the call for a cheaper, home-brew version has quickly grown.

DIY 30KM/H ELECTRIC SKATEBOARD – RASPBERRY PI/WIIMOTE POWERED

Over the summer, I made my own electric skateboard using a £4 Raspberry Pi Zero. Controlled with a Nintendo Wiimote, capable of going 30km/h, and with a range of over 10km, this project has been pretty darn fun. In this video, you see me racing around Cambridge and I explain the ins and outs of this project.

Using a Raspberry Pi Zero, a Nintendo Wii Remote, and a little help from members of the Cambridge Makespace community, Matt built a board capable of reaching 30km/h, with a battery range of 10km per charge. Alongside Neistat, Matt attributes the project inspiration to Australian student Tim Maier, whose build we previously covered in The MagPi.

Matthew Timmons-Brown and Eben Upton standing in a car park looking at a smartphone

LiDAR

Despite the success and the fun of the electric skateboard (including convincing Raspberry Pi Trading CEO Eben Upton to have a go for local television news coverage), the project Matt is most proud of is his wireless LiDAR system for theoretical use on the Mars rovers.

Matthew Timmons-Brown's LiDAR project for scanning terrains with lasers

Using a tablet app to define the angles, Matt’s A Level coursework LiDAR build scans the surrounding area, returning the results to the touchscreen, where they can be manipulated by the user. With his passion for the cosmos and the International Space Station, it’s no wonder that this is Matt’s proudest build.

Built for his A Level Computer Science coursework, the build demonstrates Matt’s passion for space and physics. Used as a means of surveying terrain, LiDAR uses laser light to measure distance, allowing users to create 3D-scanned, high-resolution maps of a specific area. It is a perfect technology for exploring unknown worlds.

Matthew Timmons-Brown and two other young people at a reception in the Houses of Parliament

Matt was invited to St James’s Palace and the Houses of Parliament as part of the Raspberry Pi community celebrations in 2016

Joining the community

In a recent interview at Hills Road Sixth Form College, where he is studying mathematics, further mathematics, physics, and computer science, Matt revealed where his love of electronics and computer science started. “I originally became interested in computer science in 2012, when I read a tiny magazine article about a computer that I would be able to buy with pocket money. This was a pretty exciting thing for a 12-year-old! Your own computer… for less than £30?!” He went on to explain how it became his mission to learn all he could on the subject and how, months later, his YouTube channel came to life, cementing him firmly into the Raspberry Pi community

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BitBarista: a fully autonomous corporation

Post Syndicated from Alex Bate original https://www.raspberrypi.org/blog/bitbarista/

To some people, the idea of a fully autonomous corporation might seem like the beginning of the end. However, while the BitBarista coffee machine prototype can indeed run itself without any human interference, it also teaches a lesson about ethical responsibility and the value of quality.

BitBarista

Bitcoin coffee machine that engages coffee drinkers in the value chain

Autonomous corporations

If you’ve played Paperclips, you get it. And in case you haven’t played Paperclips, I will only say this: give a robot one job and full control to complete the task, and things may turn in a very unexpected direction. Or, in the case of Rick and Morty, they end in emotional breakdown.

BitBarista

While the fully autonomous BitBarista resides primarily on the drawing board, the team at the University of Edinburgh’s Center for Design Informatics have built a proof-of-concept using a Raspberry Pi and a Delonghi coffee maker.

BitBarista fully autonomous coffee machine using Raspberry Pi

Recently described by the BBC as ‘a coffee machine with a life of its own, dispensing coffee to punters with an ethical preference’, BitBarista works in conjunction with customers to source coffee and complete maintenance tasks in exchange for BitCoin payments. Customers pay for their coffee in BitCoin, and when BitBarista needs maintenance such as cleaning, water replenishment, or restocking, it can pay the same customers for completing those tasks.

BitBarista fully autonomous coffee machine using Raspberry Pi

Moreover, customers choose which coffee beans the machine purchases based on quality, price, environmental impact, and social responsibility. BitBarista also collects and displays data on the most common bean choices.

BitBarista fully autonomous coffee machine using Raspberry Pi

So not only is BitBarista a study into the concept of full autonomy, it’s also a means of data collection about the societal preference of cost compared to social and environmental responsibility.

For more information on BitBarista, visit the Design Informatics and PETRAS websites.

Home-made autonomy

Many people already have store-bought autonomous technology within their homes, such as the Roomba vacuum cleaner or the Nest Smart Thermostat. And within the maker community, many more still have created such devices using sensors, mobile apps, and microprocessors such as the Raspberry Pi. We see examples using the Raspberry Pi on a daily basis, from simple motion-controlled lights and security cameras to advanced devices using temperature sensors and WiFi technology to detect the presence of specific people.

How to Make a Smart Security Camera with a Raspberry Pi Zero

In this video, we use a Raspberry Pi Zero W and a Raspberry Pi camera to make a smart security camera! The camera uses object detection (with OpenCV) to send you an email whenever it sees an intruder. It also runs a webcam so you can view live video from the camera when you are away.

To get started building your own autonomous technology, you could have a look at our resources Laser tripwire and Getting started with picamera. These will help you build a visitor register of everyone who crosses the threshold a specific room.

Or build your own Raspberry Pi Zero W Butter Robot for the lolz.

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Derek Woodroffe’s steampunk tentacle hat

Post Syndicated from Janina Ander original https://www.raspberrypi.org/blog/steampunk-tentacle-hat/

Halloween: that glorious time of year when you’re officially allowed to make your friends jump out of their skin with your pranks. For those among us who enjoy dressing up, Halloween is also the occasion to go all out with costumes. And so, dear reader, we present to you: a steampunk tentacle hat, created by Derek Woodroffe.

Finished Tenticle hat

Finished Tenticle hat

Extreme Electronics

Derek is an engineer who loves all things electronics. He’s part of Extreme Kits, and he runs the website Extreme Electronics. Raspberry Pi Zero-controlled Tesla coils are Derek’s speciality — he’s even been on one of the Royal Institution’s Christmas Lectures with them! Skip ahead to 15:06 in this video to see Derek in action:

Let There Be Light! // 2016 CHRISTMAS LECTURES with Saiful Islam – Lecture 1

The first Lecture from Professor Saiful Islam’s 2016 series of CHRISTMAS LECTURES, ‘Supercharged: Fuelling the future’. Watch all three Lectures here: http://richannel.org/christmas-lectures 2016 marked the 80th anniversary since the BBC first broadcast the Christmas Lectures on TV. To celebrate, chemist Professor Saiful Islam explores a subject that the lectures’ founder – Michael Faraday – addressed in the very first Christmas Lectures – energy.

Wearables

Wearables are electronically augmented items you can wear. They might take the form of spy eyeglasses, clothes with integrated sensors, or, in this case, headgear adorned with mechanised tentacles.

Why did Derek make this? We’re not entirely sure, but we suspect he’s a fan of the Cthulu mythos. In any case, we were a little astounded by his project. This is how we reacted when Derek tweeted us about it:

Raspberry Pi on Twitter

@ExtElec @extkits This is beyond incredible and completely unexpected.

In fact, we had to recover from a fit of laughter before we actually managed to type this answer.

Making a steampunk tentacle hat

Derek made the ‘skeleton’ of each tentacle out of a net curtain spring, acrylic rings, and four lengths of fishing line. Two servomotors connect to two ends of fishing line each, and pull them to move the tentacle.

net curtain spring and acrylic rings forming a mechanic tentacle skeleton - steampunk tentacle hat by Derek Woodroffe
Two servos connecting to lengths of fishing line - steampunk tentacle hat by Derek Woodroffe

Then he covered the tentacles with nylon stockings and liquid latex, glued suckers cut out of MDF onto them, and mounted them on an acrylic base. The eight motors connect to a Raspberry Pi via an I2C 8-port PWM controller board.

artificial tentacles - steampunk tentacle hat by Derek Woodroffe
8 servomotors connected to a controller board and a raspberry pi- steampunk tentacle hat by Derek Woodroffe

The Pi makes the servos pull the tentacles so that they move in sine waves in both the x and y directions, seemingly of their own accord. Derek cut open the top of a hat to insert the mounted tentacles, and he used more liquid latex to give the whole thing a slimy-looking finish.

steampunk tentacle hat by Derek Woodroffe

Iä! Iä! Cthulhu fhtagn!

You can read more about Derek’s steampunk tentacle hat here. He will be at the Beeston Raspberry Jam in November to show off his build, so if you’re in the Nottingham area, why not drop by?

Wearables for Halloween

This build is already pretty creepy, but just imagine it with a sensor- or camera-powered upgrade that makes the tentacles reach for people nearby. You’d have nightmare fodder for weeks.

With the help of the Raspberry Pi, any Halloween costume can be taken to the next level. How could Pi technology help you to win that coveted ‘Scariest costume’ prize this year? Tell us your ideas in the comments, and be sure to share pictures of you in your get-up with us on Twitter, Facebook, or Instagram.

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Introducing Cost Allocation Tags for Amazon SQS

Post Syndicated from Jeff Barr original https://aws.amazon.com/blogs/aws/introducing-cost-allocation-tags-for-amazon-sqs/

You have long had the ability to tag your AWS resources and to see cost breakouts on a per-tag basis. Cost allocation was launched in 2012 (see AWS Cost Allocation for Customer Bills) and we have steadily added support for additional services, most recently DynamoDB (Introducing Cost Allocation Tags for Amazon DynamoDB), Lambda (AWS Lambda Supports Tagging and Cost Allocations), and EBS (New – Cost Allocation for AWS Snapshots).

Today, we are launching tag-based cost allocation for Amazon Simple Queue Service (SQS). You can now assign tags to your queues and use them to manage your costs at any desired level: application, application stage (for a loosely coupled application that communicates via queues), project, department, or developer. After you have tagged your queues, you can use the AWS Tag Editor to search queues that have tags of interest.

Here’s how I would add three tags (app, stage, and department) to one of my queues:

This feature is available now in all AWS Regions and you can start using in today! To learn more about tagging, read Tagging Your Amazon SQS Queues. To learn more about cost allocation via tags, read Using Cost Allocation Tags. To learn more about how to use message queues to build loosely coupled microservices for modern applications, read our blog post (Building Loosely Coupled, Scalable, C# Applications with Amazon SQS and Amazon SNS) and watch the recording of our recent webinar, Decouple and Scale Applications Using Amazon SQS and Amazon SNS.

If you are coming to AWS re:Invent, plan to attend session ARC 330: How the BBC Built a Massive Media Pipeline Using Microservices. In the talk you will find out how they used SNS and SQS to improve the elasticity and reliability of the BBC iPlayer architecture.

Jeff;

Обществените медии в цифровото време

Post Syndicated from nellyo original https://nellyo.wordpress.com/2017/09/18/mills/

Том Милс е професор по социология, автор на книга за  Би Би Си (‘The BBC: Myth of a Public Service’). В публикация от тази седмица, наречена Бъдещето на БиБиСи, Милс споделя идеи за бъдещето  на БиБиСи, на първо място за бъдещето на таксите. От класическата телевизия все повече се върви към услуги онлайн – и във връзка с това  Милс предлага идеи. Не всички са ясни, не е ясно  дали и как могат да бъдат реализирани, някои са крайни,  но отбелязвам публикацията – най-малко защото се признава, че таксите в Обединеното кралство изобщо не са  такси в стриктния смисъл, нито са гаранция за независимост. Някои от акцентите:

1. Това, от което се нуждаем, е решение за цифровото време.  Най-очевидна опция е такси да се събират от потребителите на цифрови услуги, не само от собственици на оборудване за наземно приемане. Друга опция е такси да се събират от посредниците (смесен вариант: и от посредниците). Трети вариант е финансирането да е от данъци, пише Милс.

2. Във всеки случай приходите трябва да са стабилни и финансирането да е независимо от политически контрол – сега се твърди, че таксите за гаранция за независимостта на БиБиСи, но – напротив – те често са служили като инструмент за влияние на правителството.

3. По независим начин трябва да се определя размерът на финансирането. При това следва да се вземе предвид уникалното място на обществените медии:

Адекватното регулиране не може да се основава на предположението, че конкуренцията на пазара ще доведе непременно до плурализъм; че това, което е добро за пазара и това, което е полезно за обществото, е задължително едно и също; или че единствената подходяща роля на обществените доставчици е да предлагат това, което пазарът не може.

4. Съществуващата  такса не е цена за достъп до програмите на Би Би Си. Таксите са механизъм за финансиране и регулиране  като част от една по-широка обществена и демократична претенция към цифровото пространство – за  достъпен ресурс от култура и знание.

5. Лицата, отговорни за вземането на решения на върха на Би Би Си, работят в силно политизирана среда. Трябва да се мисли за по-преки форми на демократична отчетност, например пряк избор от аудиторията, а частично, част от директорите –  от аудиторията  и от служителите на Би Би Си.

6.  Програмата за децентрализация трябва да бъде в центъра на вниманието. Необходимо е практиките за набиране на персонал да бъдат строго наблюдавани и ревизирани, за да се осигури адекватно представителство на аудиторията.

7. Усилията за приближаване на Би Би Си до аудиторията ще бъдат улеснени от  данните за потребителите, събрани чрез цифровите услуги на Би Би Си. Частните компании използват  такива данни, за да монетизират своите платформи – наблюдението на потребителите е с цел  печалба.  Би Би Си ще може да се възползва от всички предимства на цифровите медии, без да е необходимо да  регулира съдържанието в съответствие с търговските императиви. Основен въпрос тук е алгоритмичната прозрачност и отчетност.

Всички данни, събрани и съхранявани, би трябвало да са достъпни не само за самата Би Би Си, но и за други потребители в ясен и достъпен формат, което означава, че Би Би Си може да улесни общественото ни познаване на себе си и на другите, а не просто събирането на данни за аудиторията, за да се осигури по-добро обслужване. По този начин гражданите на Обединеното кралство, а не шепа корпорации, ще поемат водеща роля в оформянето на начина, по който се развива онлайн пространството.

8. На всекиго трябва да бъде даден неограничен достъп до отворен ресурс за култура и знание. Правилата за интелектуалната собственост  да бъдат преразгледани, така че всички програми на Би Би Си да са достъпни завинаги. Ще трябва да продължат усилията за отваряне на архивния материал на Би Би Си и на други форми на култура и обществено знание.

9. Политиката към независимите продукции трябва да бъде преразгледана и да бъде подчинена на интересите на аудиторията, а не на други интереси. Трябва да бъдат гарантирани собствените продукции. Заедно с това  – в  съчетание с амбициозна програма за цифровизация, демократизация и децентрализация  – Би Би Си може да се отвори за огромния обем неизползван талант и да създаде нови хоризонтални мрежи, които ще позволят на аудиторията да създава и открива нови идеи и нови форми на култура на мащаб невъзможно в пред-цифровата ера.

10.   Смисленото участие в развитието на обществото сега зависи от достъпа до онлайн пространството, което   бързо се монополизира  от   малък брой неотчетни пред обществото   многонационални корпорации. Необходимо е преосмисляне на обществените медии  като демократична медийна платформа,  ориентирана към технологиите, експертизата и културата – за  преодоляване на сериозния демократичен дефицит.

 

Filed under: Digital, Media Law

Landmine-clearing Pi-powered C-Turtle

Post Syndicated from Janina Ander original https://www.raspberrypi.org/blog/landmine-c-turtle/

In an effort to create a robot that can teach itself to navigate different terrains, scientists at Arizona State University have built C-Turtle, a Raspberry Pi-powered autonomous cardboard robot with turtle flippers. This is excellent news for people who live in areas with landmines: C-Turtle is a great alternative to current landmine-clearing robots, since it is much cheaper, and much easier to assemble.

C-Turtle ASU

Photo by Charlie Leight/ASU Now

Why turtle flippers?

As any user of Python will tell you*, turtles are amazing. Moreover, as the evolutionary biologist of the C-Turtle team, Andrew Jansen, will tell you, considering their bulk** turtles move very well on land with the help of their flippers. Consequently, the team tried out prototypes with cardboard flippers imitating the shape of turtle flippers. Then they compared their performance to that of prototypes with rectangular or oval ‘flippers’. And 157 million years of evolution*** won out: the robots with turtle flippers were best at moving forward.

C-Turtle ASU

Field testing with Assistant Professor Heni Ben Amor, one of the C-Turtle team’s leaders (Photo by Charlie Leight/ASU Now)

If it walks like a C-Turtle…

But the scientists didn’t just slap turtle flippers on their robot and then tell it to move like a turtle! Instead, they implemented machine learning algorithms on the Pi Zero that serves as C-Turtle’s brain, and then simply let the robot do its thing. Left to its own devices, it used the reward and punishment mechanisms of its algorithms to learn the most optimal way of propelling itself forward. And lo and behold, C-Turtle taught itself to move just like a live turtle does!

Robotic C-Turtle

This is “Robotic C-Turtle” by ASU Now on Vimeo, the home for high quality videos and the people who love them.

Landmine clearance with C-Turtle

Robots currently used to clear landmines are very expensive, since they are built to withstand multiple mine explosions. Conversely, the total cost of C-Turtle comes to about $70 (~£50) – that’s cheap enough to make it disposable. It is also more easily assembled, it doesn’t need to be remotely controlled, and it can learn to navigate new terrains. All this makes it perfect for clearing minefields.

BBC Click on Twitter

Meet C-Turtle, the landmine detecting robot. VIDEO https://t.co/Kjc6WxRC8I

C-Turtles in space?****

The researchers hope that robots similar to C-Turtle can used for space exploration. They found that the C-Turtle prototypes that had performed very well in the sandpits in their lab didn’t really do as well when they were released in actual desert conditions. By analogy, robots optimized for simulated planetary conditions might not actually perform well on-site. The ASU scientists imagine that C-Turtle materials and a laser cutter for the cardboard body could be carried on board a Mars mission. Then Martian C-Turtle design could be optimized after landing, and the robot could teach itself how best to navigate real Martian terrain.

There are already Raspberry Pis in space – imagine if they actually made it to Mars! Dave would never recover

Congrats to Assistant Professors Heni Ben Amor and Daniel Aukes, and to the rest of the C-Turtle team, on their achievement! We at Pi Towers are proud that our little computer is part of this amazing project.

C-Turtle ASU

Photo by Charlie Leight/ASU Now

* Check out our Turtley amazing resource to find out why!

** At a length of 7ft, leatherback sea turtles can weigh 1,500lb!

*** That’s right: turtles survived the extinction of the dinosaurs!

**** Is anyone else thinking of Great A’Tuin right now? Anyone? Just me? Oh well.

The post Landmine-clearing Pi-powered C-Turtle appeared first on Raspberry Pi.

Taking the first step on the journey

Post Syndicated from Matt Richardson original https://www.raspberrypi.org/blog/taking-first-step-journey/

This column is from The MagPi issue 58. You can download a PDF of the full issue for free, or subscribe to receive the print edition in your mailbox or the digital edition on your tablet. All proceeds from the print and digital editions help the Raspberry Pi Foundation achieve its charitable goals.

About five years ago was the first time I unboxed a Raspberry Pi. I hooked it up to our living room television and made space on the TV stand for an old USB keyboard and mouse. Watching the $35 computer boot up for the first time impressed me, and I had a feeling it was a big deal, but I’ll admit that I had no idea how much of a phenomenon Raspberry Pi would become. I had no idea how large the community would grow. I had no idea how much my life would be changed from that moment on. And it all started with a simple first step: booting it up.

Matt Richardson on Twitter

Finally a few minutes to experiment with @Raspberry_Pi! So far, I’m rather impressed!

The key to the success of Raspberry Pi as a computer – and, in turn, a community and a charitable foundation – is that there’s a low barrier to the first step you take with it. The low price is a big reason for that. Whether or not to try Raspberry Pi is not a difficult decision. Since it’s so affordable, you can just give it a go, and see how you get along.

The pressure is off

Linus Torvalds, the creator of the Linux operating system kernel, talked about this in a BBC News interview in 2012. He explained that a lot of people might take the first step with Raspberry Pi, but not everyone will carry on with it. But getting more people to take that first step of turning it on means there are more people who potentially will be impacted by the technology. Torvalds said:

I find things like Raspberry Pi to be an important thing: trying to make it possible for a wider group of people to tinker with computers. And making the computers cheap enough that you really can not only afford the hardware at a big scale, but perhaps more important, also afford failure.

In other words, if things don’t work out with you and your Raspberry Pi, it’s not a big deal, since it’s such an affordable computer.

In this together

Of course, we hope that more and more people who boot up a Raspberry Pi for the first time will decide to continue experimenting, creating, and learning with it. Thanks to improvements to the hardware, the Raspbian operating system, and free software packages, it’s constantly becoming easier to do many amazing things with this little computer. And our continually growing community means you’re not alone on this journey. These improvements and growth over the past few years hopefully encourage more people who boot up Raspberry Pis to keep exploring.
raspberry pi first step

The first step

However, the important thing is that people are given the opportunity to take that first step, especially young people. Young learners are at a critical age, and something like the Raspberry Pi can have an enormously positive impact on the rest of their lives. It’s a major reason why our free resources are aimed at young learners. It’s also why we train educators all over the world for free. And encouraging youngsters to take their first step with Raspberry Pi could not only make a positive difference in their lives, but also in society at large.

With the affordable computational power, excellent software, supportive community, and free resources, you’re given everything you need to make a big impact in the world when you boot up a Raspberry Pi for the first time. That moment could be step one of ten, or one of ten thousand, but it’s up to you to take that first step.

Now you!

Learning and making things with the Pi is incredibly easy, and we’ve created numerous resources and tutorials to help you along. First of all, check out our hardware guide to make sure you’re all set up. Next, you can try out Scratch and Python, our favourite programming languages. Feeling creative? Learn to code music with Sonic Pi, or make visual art with Processing. Ready to control the real world with your Pi? Create a reaction game, or an LED adornment for your clothing. Maybe you’d like to do some science with the help of our Sense HAT, or become a film maker with our camera?

You can do all this with the Raspberry Pi, and so much more. The possibilities are as limitless as your imagination. So where do you want to start?

The post Taking the first step on the journey appeared first on Raspberry Pi.

How to Deploy Local Administrator Password Solution with AWS Microsoft AD

Post Syndicated from Dragos Madarasan original https://aws.amazon.com/blogs/security/how-to-deploy-local-administrator-password-solution-with-aws-microsoft-ad/

Local Administrator Password Solution (LAPS) from Microsoft simplifies password management by allowing organizations to use Active Directory (AD) to store unique passwords for computers. Typically, an organization might reuse the same local administrator password across the computers in an AD domain. However, this approach represents a security risk because it can be exploited during lateral escalation attacks. LAPS solves this problem by creating unique, randomized passwords for the Administrator account on each computer and storing it encrypted in AD.

Deploying LAPS with AWS Microsoft AD requires the following steps:

  1. Install the LAPS binaries on instances joined to your AWS Microsoft AD domain. The binaries add additional client-side extension (CSE) functionality to the Group Policy client.
  2. Extend the AWS Microsoft AD schema. LAPS requires new AD attributes to store an encrypted password and its expiration time.
  3. Configure AD permissions and delegate the ability to retrieve the local administrator password for IT staff in your organization.
  4. Configure Group Policy on instances joined to your AWS Microsoft AD domain to enable LAPS. This configures the Group Policy client to process LAPS settings and uses the binaries installed in Step 1.

The following diagram illustrates the setup that I will be using throughout this post and the associated tasks to set up LAPS. Note that the AWS Directory Service directory is deployed across multiple Availability Zones, and monitoring automatically detects and replaces domain controllers that fail.

Diagram illustrating this blog post's solution

In this blog post, I explain the prerequisites to set up Local Administrator Password Solution, demonstrate the steps involved to update the AD schema on your AWS Microsoft AD domain, show how to delegate permissions to IT staff and configure LAPS via Group Policy, and demonstrate how to retrieve the password using the graphical user interface or with Windows PowerShell.

This post assumes you are familiar with Lightweight Directory Access Protocol Data Interchange Format (LDIF) files and AWS Microsoft AD. If you need more of an introduction to Directory Service and AWS Microsoft AD, see How to Move More Custom Applications to the AWS Cloud with AWS Directory Service, which introduces working with schema changes in AWS Microsoft AD.

Prerequisites

In order to implement LAPS, you must use AWS Directory Service for Microsoft Active Directory (Enterprise Edition), also known as AWS Microsoft AD. Any instance on which you want to configure LAPS must be joined to your AWS Microsoft AD domain. You also need a Management instance on which you install the LAPS management tools.

In this post, I use an AWS Microsoft AD domain called example.com that I have launched in the EU (London) region. To see which the regions in which Directory Service is available, see AWS Regions and Endpoints.

Screenshot showing the AWS Microsoft AD domain example.com used in this blog post

In addition, you must have at least two instances launched in the same region as the AWS Microsoft AD domain. To join the instances to your AWS Microsoft AD domain, you have two options:

  1. Use the Amazon EC2 Systems Manager (SSM) domain join feature. To learn more about how to set up domain join for EC2 instances, see joining a Windows Instance to an AWS Directory Service Domain.
  2. Manually configure the DNS server addresses in the Internet Protocol version 4 (TCP/IPv4) settings of the network card to use the AWS Microsoft AD DNS addresses (172.31.9.64 and 172.31.16.191, for this blog post) and perform a manual domain join.

For the purpose of this post, my two instances are:

  1. A Management instance on which I will install the management tools that I have tagged as Management.
  2. A Web Server instance on which I will be deploying the LAPS binary.

Screenshot showing the two EC2 instances used in this post

Implementing the solution

 

1. Install the LAPS binaries on instances joined to your AWS Microsoft AD domain by using EC2 Run Command

LAPS binaries come in the form of an MSI installer and can be downloaded from the Microsoft Download Center. You can install the LAPS binaries manually, with an automation service such as EC2 Run Command, or with your existing software deployment solution.

For this post, I will deploy the LAPS binaries on my Web Server instance (i-0b7563d0f89d3453a) by using EC2 Run Command:

  1. While signed in to the AWS Management Console, choose EC2. In the Systems Manager Services section of the navigation pane, choose Run Command.
  2. Choose Run a command, and from the Command document list, choose AWS-InstallApplication.
  3. From Target instances, choose the instance on which you want to deploy the LAPS binaries. In my case, I will be selecting the instance tagged as Web Server. If you do not see any instances listed, make sure you have met the prerequisites for Amazon EC2 Systems Manager (SSM) by reviewing the Systems Manager Prerequisites.
  4. For Action, choose Install, and then stipulate the following values:
    • Parameters: /quiet
    • Source: https://download.microsoft.com/download/C/7/A/C7AAD914-A8A6-4904-88A1-29E657445D03/LAPS.x64.msi
    • Source Hash: f63ebbc45e2d080630bd62a195cd225de734131a56bb7b453c84336e37abd766
    • Comment: LAPS deployment

Leave the other options with the default values and choose Run. The AWS Management Console will return a Command ID, which will initially have a status of In Progress. It should take less than 5 minutes to download and install the binaries, after which the Command ID will update its status to Success.

Status showing the binaries have been installed successfully

If the Command ID runs for more than 5 minutes or returns an error, it might indicate a problem with the installer. To troubleshoot, review the steps in Troubleshooting Systems Manager Run Command.

To verify the binaries have been installed successfully, open Control Panel and review the recently installed applications in Programs and Features.

Screenshot of Control Panel that confirms LAPS has been installed successfully

You should see an entry for Local Administrator Password Solution with a version of 6.2.0.0 or newer.

2. Extend the AWS Microsoft AD schema

In the previous section, I used EC2 Run Command to install the LAPS binaries on an EC2 instance. Now, I am ready to extend the schema in an AWS Microsoft AD domain. Extending the schema is a requirement because LAPS relies on new AD attributes to store the encrypted password and its expiration time.

In an on-premises AD environment, you would update the schema by running the Update-AdmPwdADSchema Windows PowerShell cmdlet with schema administrator credentials. Because AWS Microsoft AD is a managed service, I do not have permissions to update the schema directly. Instead, I will update the AD schema from the Directory Service console by importing an LDIF file. If you are unfamiliar with schema updates or LDIF files, see How to Move More Custom Applications to the AWS Cloud with AWS Directory Service.

To make things easier for you, I am providing you with a sample LDIF file that contains the required AD schema changes. Using Notepad or a similar text editor, open the SchemaChanges-0517.ldif file and update the values of dc=example,dc=com with your own AWS Microsoft AD domain and suffix.

After I update the LDIF file with my AWS Microsoft AD details, I import it by using the AWS Management Console:

  1. On the Directory Service console, select from the list of directories in the Microsoft AD directory by choosing its identifier (it will look something like d-534373570ea).
  2. On the Directory details page, choose the Schema extensions tab and choose Upload and update schema.
    Screenshot showing the "Upload and update schema" option
  3. When prompted for the LDIF file that contains the changes, choose the sample LDIF file.
  4. In the background, the LDIF file is validated for errors and a backup of the directory is created for recovery purposes. Updating the schema might take a few minutes and the status will change to Updating Schema. When the process has completed, the status of Completed will be displayed, as shown in the following screenshot.

Screenshot showing the schema updates in progress
When the process has completed, the status of Completed will be displayed, as shown in the following screenshot.

Screenshot showing the process has completed

If the LDIF file contains errors or the schema extension fails, the Directory Service console will generate an error code and additional debug information. To help troubleshoot error messages, see Schema Extension Errors.

The sample LDIF file triggers AWS Microsoft AD to perform the following actions:

  1. Create the ms-Mcs-AdmPwd attribute, which stores the encrypted password.
  2. Create the ms-Mcs-AdmPwdExpirationTime attribute, which stores the time of the password’s expiration.
  3. Add both attributes to the Computer class.

3. Configure AD permissions

In the previous section, I updated the AWS Microsoft AD schema with the required attributes for LAPS. I am now ready to configure the permissions for administrators to retrieve the password and for computer accounts to update their password attribute.

As part of configuring AD permissions, I grant computers the ability to update their own password attribute and specify which security groups have permissions to retrieve the password from AD. As part of this process, I run Windows PowerShell cmdlets that are not installed by default on Windows Server.

Note: To learn more about Windows PowerShell and the concept of a cmdlet (pronounced “command-let”), go to Getting Started with Windows PowerShell.

Before getting started, I need to set up the required tools for LAPS on my Management instance, which must be joined to the AWS Microsoft AD domain. I will be using the same LAPS installer that I downloaded from the Microsoft LAPS website. In my Management instance, I have manually run the installer by clicking the LAPS.x64.msi file. On the Custom Setup page of the installer, under Management Tools, for each option I have selected Install on local hard drive.

Screenshot showing the required management tools

In the preceding screenshot, the features are:

  • The fat client UI – A simple user interface for retrieving the password (I will use it at the end of this post).
  • The Windows PowerShell module – Needed to run the commands in the next sections.
  • The GPO Editor templates – Used to configure Group Policy objects.

The next step is to grant computers in the Computers OU the permission to update their own attributes. While connected to my Management instance, I go to the Start menu and type PowerShell. In the list of results, right-click Windows PowerShell and choose Run as administrator and then Yes when prompted by User Account Control.

In the Windows PowerShell prompt, I type the following command.

Import-module AdmPwd.PS

Set-AdmPwdComputerSelfPermission –OrgUnit “OU=Computers,OU=MyMicrosoftAD,DC=example,DC=com

To grant the administrator group called Admins the permission to retrieve the computer password, I run the following command in the Windows PowerShell prompt I previously started.

Import-module AdmPwd.PS

Set-AdmPwdReadPasswordPermission –OrgUnit “OU=Computers, OU=MyMicrosoftAD,DC=example,DC=com” –AllowedPrincipals “Admins”

4. Configure Group Policy to enable LAPS

In the previous section, I deployed the LAPS management tools on my management instance, granted the computer accounts the permission to self-update their local administrator password attribute, and granted my Admins group permissions to retrieve the password.

Note: The following section addresses the Group Policy Management Console and Group Policy objects. If you are unfamiliar with or wish to learn more about these concepts, go to Get Started Using the GPMC and Group Policy for Beginners.

I am now ready to enable LAPS via Group Policy:

  1. On my Management instance (i-03b2c5d5b1113c7ac), I have installed the Group Policy Management Console (GPMC) by running the following command in Windows PowerShell.
Install-WindowsFeature –Name GPMC
  1. Next, I have opened the GPMC and created a new Group Policy object (GPO) called LAPS GPO.
  2. In the Local Group Policy Editor, I navigate to Computer Configuration > Policies > Administrative Templates > LAPS. I have configured the settings using the values in the following table.

Setting

State

Options

Password Settings

Enabled

Complexity: large letters, small letters, numbers, specials

Do not allow password expiration time longer than required by policy

Enabled

N/A

Enable local admin password management

Enabled

N/A

  1. Next, I need to link the GPO to an organizational unit (OU) in which my machine accounts sit. In your environment, I recommend testing the new settings on a test OU and then deploying the GPO to production OUs.

Note: If you choose to create a new test organizational unit, you must create it in the OU that AWS Microsoft AD delegates to you to manage. For example, if your AWS Microsoft AD directory name were example.com, the test OU path would be example.com/example/Computers/Test.

  1. To test that LAPS works, I need to make sure the computer has received the new policy by forcing a Group Policy update. While connected to the Web Server instance (i-0b7563d0f89d3453a) using Remote Desktop, I open an elevated administrative command prompt and run the following command: gpupdate /force. I can check if the policy is applied by running the command: gpresult /r | findstr LAPS GPO, where LAPS GPO is the name of the GPO created in the second step.
  2. Back on my Management instance, I can then launch the LAPS interface from the Start menu and use it to retrieve the password (as shown in the following screenshot). Alternatively, I can run the Get-ADComputer Windows PowerShell cmdlet to retrieve the password.
Get-ADComputer [YourComputerName] -Properties ms-Mcs-AdmPwd | select name, ms-Mcs-AdmPwd

Screenshot of the LAPS UI, which you can use to retrieve the password

Summary

In this blog post, I demonstrated how you can deploy LAPS with an AWS Microsoft AD directory. I then showed how to install the LAPS binaries by using EC2 Run Command. Using the sample LDIF file I provided, I showed you how to extend the schema, which is a requirement because LAPS relies on new AD attributes to store the encrypted password and its expiration time. Finally, I showed how to complete the LAPS setup by configuring the necessary AD permissions and creating the GPO that starts the LAPS password change.

If you have comments about this post, submit them in the “Comments” section below. If you have questions about or issues implementing this solution, please start a new thread on the Directory Service forum.

– Dragos