From 2be7522164a8ae230f2266ca7d00c14f48bd85f7 Mon Sep 17 00:00:00 2001 From: =?UTF-8?q?Tobias=20Nie=C3=9Fen?= Date: Sat, 2 Apr 2022 18:17:56 +0200 Subject: [PATCH] doc: remove faulty justification for 128-bit AES This sentence implies that AES-128 is preferred over AES-256 because of a related-key attack from 2009. However, that attack by Alex Biryukov, Orr Dunkelman, Nathan Keller, Dmitry Khovratovich, and Adi Shamir, while impressive, is only effective against variants of AES-256 with a reduced number of rounds and it requires related keys. This means that the attack is not effective against AES-256 as it is used within TLS. (AES-128 is still often preferred over AES-256 simply because it is believed to be sufficiently secure and because it is faster.) --- doc/api/tls.md | 4 ---- 1 file changed, 4 deletions(-) diff --git a/doc/api/tls.md b/doc/api/tls.md index 65fb7eda4e0dfc..0c19a7537d3605 100644 --- a/doc/api/tls.md +++ b/doc/api/tls.md @@ -385,9 +385,6 @@ The default cipher suite prefers GCM ciphers for [Chrome's 'modern cryptography' setting][] and also prefers ECDHE and DHE ciphers for perfect forward secrecy, while offering _some_ backward compatibility. -128 bit AES is preferred over 192 and 256 bit AES in light of [specific -attacks affecting larger AES key sizes][]. - Old clients that rely on insecure and deprecated RC4 or DES-based ciphers (like Internet Explorer 6) cannot complete the handshaking process with the default configuration. If these clients _must_ be supported, the @@ -2268,4 +2265,3 @@ added: v11.4.0 [cipher list format]: https://www.openssl.org/docs/man1.1.1/man1/ciphers.html#CIPHER-LIST-FORMAT [forward secrecy]: https://en.wikipedia.org/wiki/Perfect_forward_secrecy [perfect forward secrecy]: #perfect-forward-secrecy -[specific attacks affecting larger AES key sizes]: https://www.schneier.com/blog/archives/2009/07/another_new_aes.html