tree 98e584bd155f0270b780dc8830c86efe211e8cf1
parent 91b2501f02e9cfa1643f90b5dfd3ae397b75922b
author Adam Langley <alangley@gmail.com> 1452885401 -0800
committer Adam Langley <alangley@gmail.com> 1453932301 +0000

Use Barrett reduction in CBC processing rather than tricks.

Division isn't constant-time on Intel chips so the code was adding a
large multiple of md_size to try and force the operation to always take
the maximum amount of time.

I'm less convinced, these days, that compilers aren't going to get smart
enough to optimise that away so use Barrett reduction instead.

Change-Id: Ib8c514192682a2fcb4b1fb7e7c6dd1301d9888d0
Reviewed-on: https://boringssl-review.googlesource.com/6906
Reviewed-by: David Benjamin <davidben@chromium.org>
Reviewed-by: Adam Langley <alangley@gmail.com>