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author | Jack Lloyd <[email protected]> | 2018-02-24 10:29:27 -0500 |
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committer | Jack Lloyd <[email protected]> | 2018-02-24 10:29:27 -0500 |
commit | 7ba53cde04f255662891ce75d6df922e2a7b45ac (patch) | |
tree | aae8f6dc75a2fa02b49ce8101be5821b8a10c219 /doc/manual/side_channels.rst | |
parent | 052aa347142f122da3f28513b42c8c3f3d6dc23f (diff) |
Update news/docs
Diffstat (limited to 'doc/manual/side_channels.rst')
-rw-r--r-- | doc/manual/side_channels.rst | 12 |
1 files changed, 5 insertions, 7 deletions
diff --git a/doc/manual/side_channels.rst b/doc/manual/side_channels.rst index 7cf8a7b35..01d20a66d 100644 --- a/doc/manual/side_channels.rst +++ b/doc/manual/side_channels.rst @@ -210,9 +210,9 @@ bytes runs in constant time, depending only on the block size of the cipher. AES ---------------------- -On x86 processors which support it, AES-NI instruction set is used, as it is -fast and (presumed) side channel silent. There is no support at the moment for -the similar ARMv8 or POWER AES instructions; patches would be welcome. +Some x86, ARMv8 and POWER processors support AES instructions which +are fast and are thought to be side channel silent. These instructions +are used when available. On x86 processors without AES-NI but with SSSE3 (which includes older Intel Atoms and Core2 Duos, and even now some embedded or low power x86 chips), a @@ -239,10 +239,8 @@ GCM On platforms that support a carryless multiply instruction (recent x86 and ARM), GCM is fast and constant time. -On all other platforms, GCM is slow and constant time. It uses a simple bit at -at time loop. It would be much faster using a table lookup, but we wish to avoid -side channels. One improvement here would be the option of using a 2K or 4K -table, but using a side-channel silent (masked) table lookup. +On all other platforms, GCM uses a slow but constant time algorithm. There is +also an SSSE3 variant of the same (still slow) algorithm. OCB ----------------------- |