Tag Archives: Certificate Authorities

E-Mailing Private HTTPS Keys

Post Syndicated from Bruce Schneier original https://www.schneier.com/blog/archives/2018/03/e-mailing_priva.html

I don’t know what to make of this story:

The email was sent on Tuesday by the CEO of Trustico, a UK-based reseller of TLS certificates issued by the browser-trusted certificate authorities Comodo and, until recently, Symantec. It was sent to Jeremy Rowley, an executive vice president at DigiCert, a certificate authority that acquired Symantec’s certificate issuance business after Symantec was caught flouting binding industry rules, prompting Google to distrust Symantec certificates in its Chrome browser. In communications earlier this month, Trustico notified DigiCert that 50,000 Symantec-issued certificates Trustico had resold should be mass revoked because of security concerns.

When Rowley asked for proof the certificates were compromised, the Trustico CEO emailed the private keys of 23,000 certificates, according to an account posted to a Mozilla security policy forum. The report produced a collective gasp among many security practitioners who said it demonstrated a shockingly cavalier treatment of the digital certificates that form one of the most basic foundations of website security.

Generally speaking, private keys for TLS certificates should never be archived by resellers, and, even in the rare cases where such storage is permissible, they should be tightly safeguarded. A CEO being able to attach the keys for 23,000 certificates to an email raises troubling concerns that those types of best practices weren’t followed.

I am croggled by the multiple layers of insecurity here.

BoingBoing post.

Preparing for AWS Certificate Manager (ACM) Support of Certificate Transparency

Post Syndicated from Jonathan Kozolchyk original https://aws.amazon.com/blogs/security/how-to-get-ready-for-certificate-transparency/


Starting April 30, 2018, Google Chrome will require all publicly trusted certificates to be logged in at least two Certificate Transparency logs. This means that any certificate issued that is not logged will result in an error message in Google Chrome. Beginning April 24, 2018, Amazon will log all new and renewed certificates in at least two public logs unless you disable Certificate Transparency logging.

Without Certificate Transparency, it can be difficult for a domain owner to know if an unexpected certificate was issued for their domain. Under the current system, no record is kept of certificates being issued, and domain owners do not have a reliable way to identify rogue certificates.

To address this situation, Certificate Transparency creates a cryptographically secure log of each certificate issued. Domain owners can search the log to identify unexpected certificates, whether issued by mistake or malice. Domain owners can also identify Certificate Authorities (CAs) that are improperly issuing certificates. In this blog post, I explain more about Certificate Transparency and tell you how to prepare for it.

How does Certificate Transparency work?

When a CA issues a publicly trusted certificate, the CA must submit the certificate to one or more Certificate Transparency log servers. The Certificate Transparency log server responds with a signed certificate timestamp (SCT) that confirms the log server will add the certificate to the list of known certificates. The SCT is then embedded in the certificate and delivered automatically to a browser. The SCT is like a receipt that proves the certificate was published into the Certificate Transparency log. Starting April 30, Google Chrome will require an SCT as proof that the certificate was published to a Certificate Transparency log in order to trust the certificate without displaying an error message.

What is Amazon doing to support Certificate Transparency?

Certificate Transparency is a good practice. It enables AWS customers to be more confident that an unauthorized certificate hasn’t been issued by a CA. Beginning on April 24, 2018, Amazon will log all new and renewed certificates in at least two Certificate Transparency logs unless you disable Certificate Transparency logging.

We recognize that there can be times when our customers do not want to log certificates. For example, if you are building a website for an unreleased product and have registered the subdomain, newproduct.example.com, requesting a logged certificate for your domain will make it publicly known that the new product is coming. Certificate Transparency logging also can expose server hostnames that you want to keep private. Hostnames such as payments.example.com can reveal the purpose of a server and provide attackers with information about your private network. These logs do not contain the private key for your certificate. For these reasons, you will be able to disable Certificate Transparency logging on a per-certificate basis using the ACM APIs or with the AWS CLI, starting on March 27, 2018. Doing so will lead to errors in Google Chrome, which may be preferable to exposing the information. We will share instructions on the AWS Security Blog about how to disable Certificate Transparency logging as we get closer to March 27, 2018.


Beginning April 24, 2018, ACM will begin logging all new and renewed certificates by default. If you don’t want a certificate to be logged, you’ll be able to opt out using the AWS API or CLI. However, for Google Chrome to trust the certificate, all issued or imported certificates must have the SCT information embedded in them by April 30, 2018.

If you have comments about this blog post, submit them in the “Comments” section below. If you have questions, start a new thread in the ACM forum.

– Jonathan

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