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Diffstat (limited to 'src/lib/ctime/lib_ctime.md')
| -rw-r--r-- | src/lib/ctime/lib_ctime.md | 14 |
1 files changed, 14 insertions, 0 deletions
diff --git a/src/lib/ctime/lib_ctime.md b/src/lib/ctime/lib_ctime.md new file mode 100644 index 0000000000..913199f6a5 --- /dev/null +++ b/src/lib/ctime/lib_ctime.md @@ -0,0 +1,14 @@ +@dir /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. + |