commit dca3c9fff87227b8119afe804ce0ae8ed840b1f8 Author: Nick Mathewson nickm@torproject.org Date: Tue Jan 10 11:13:45 2012 -0500

Add missing documentation for counter-mode checks --- src/common/aes.c | 17 ++++++++++++----- 1 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/src/common/aes.c b/src/common/aes.c index 3c315dc..da7220f 100644 --- a/src/common/aes.c +++ b/src/common/aes.c @@ -47,8 +47,8 @@ * OpenSSL pre-1.0 (by about 10%!). But OpenSSL 1.0.0 added a counter mode * implementation faster than the one here (by about 7%). So we pick which * one to used based on the Openssl version above. (OpenSSL 1.0.0a fixed a - * critical bug in that counter mode implementation, so we actually require - * that one.) + * critical bug in that counter mode implementation, so we need to test to + * make sure that we have a fixed version.) */

/*======================================================================*/ @@ -90,12 +90,13 @@ struct aes_cnt_cipher { uint8_t using_evp; };

-/** True if we should prefer the EVP implementation for AES, either because +/** True iff we should prefer the EVP implementation for AES, either because * we're testing it or because we have hardware acceleration configured */ static int should_use_EVP = 0;

#ifdef CAN_USE_OPENSSL_CTR -/**DOCDOC*/ +/** True iff we have tested the counter-mode implementation and found that it + * doesn't have the counter-mode bug from OpenSSL 1.0.0. */ static int should_use_openssl_CTR = 0; #endif

@@ -129,7 +130,13 @@ evaluate_evp_for_aes(int force_val) return 0; }

-/**DOCDOC*/ +/** Test the OpenSSL counter mode implementation to see whether it has the + * counter-mode bug from OpenSSL 1.0.0. If the implementation works, then + * we will use it for future encryption/decryption operations. + * + * We can't just look at the OpenSSL version, since some distributions update + * their OpenSSL packages without changing the version number. + **/ int evaluate_ctr_for_aes(void) {