TLS

Because crypto is too pleasant without x509.

mkcert: valid HTTPS certificates for localhost

(or for any other names) The web is moving to HTTPS, preventing network attackers from observing or injecting page contents. But HTTPS needs TLS certificates, and while deployment is increasingly a solved issue thanks to the ACME protocol and Let's Encrypt, development still mostly ends up happening over HTTP because…

We need to talk about Session Tickets

More specifically, TLS 1.2 Session Tickets. Session Tickets, specified in RFC 5077, are a technique to resume TLS sessions by storing key material encrypted on the clients. In TLS 1.2 they speed up the handshake from two to one round-trips. Unfortunately, a combination of deployment realities and three…

Playing with kernel TLS in Linux 4.13 and Go

Linux 4.13 introduces support for nothing less than... TLS! The 1600 LoC patch allows userspace to pass the kernel the encryption keys for an established connection, making encryption happen transparently inside the kernel. The only ciphersuite supported is AES-128-GCM as per RFC 5288, meaning it only supports TLS version…

Finding Ticketbleed

Ticketbleed (CVE-2016-9244) is a software vulnerability in the TLS stack of certain F5 products that allows a remote attacker to extract up to 31 bytes of uninitialized memory at a time, which can contain any kind of random sensitive information, like in Heartbleed. If you suspect you might be affected…

TLS 1.3 at 33c3

Nick Sullivan and I gave a talk about TLS 1.3 at 33c3, the latest Chaos Communication Congress. Here's the Fahrplan entry. We spoke about the flow of TLS 1.2 vs. TLS 1.3, how it manages to save a round trip, resumption and 0-RTT, forward secrecy and replays,…