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Diffstat (limited to 'src/lib/ctime/lib_ctime.dox')
| -rw-r--r-- | src/lib/ctime/lib_ctime.dox | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/src/lib/ctime/lib_ctime.dox b/src/lib/ctime/lib_ctime.dox index 476c95991c..bf95b03165 100644 --- a/src/lib/ctime/lib_ctime.dox +++ b/src/lib/ctime/lib_ctime.dox @@ -1,4 +1,16 @@ /** @dir lib/ctime -@brief lib/ctime +@brief lib/ctime: Constant-time code to avoid side-channels. + +This module contains constant-time implementations of various +data comparison and table lookup functions. We use these in preference to +memcmp() and so forth, since memcmp() can leak information about its inputs +based on how fast it returns. In general, your code should call tor_memeq() +and tor_memneq(), not memcmp(). + +We also define some _non_-constant-time wrappers for memcmp() here: Since we +consider calls to memcmp() to be in error, we require that code that actually +doesn't need to be constant-time to use the fast_memeq() / fast_memneq() / +fast_memcmp() aliases instead. + **/ |