tree 6143f0767661da7431293d147227aa7ff23bf298
parent ad5e3e3597f98bca70b2f2e11dc439000d092a44
author David Benjamin <davidben@google.com> 1586230782 -0400
committer CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org> 1586306410 +0000

Generalize bn_from_montgomery_small.

Montgomery reduction works when the input is at most N*R (N^2 is a
tighter bound that's easier to describe and usually suffices). This is
useful when reducing product-sized values. In particular,
hash-to-curve's hash_to_field function requires a reduction. Generalize
this so we can implement it with Montgomery reduction.

Bug: chromium:1014199
Change-Id: I1a07f9b94823742384a98c0c6fecdedfe5240b7b
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/40588
Commit-Queue: David Benjamin <davidben@google.com>
Reviewed-by: Adam Langley <agl@google.com>