We currently preferentially sign the largest hash available and
advertise such a preference for signatures we accept. We're just as
happy with SHA-256 and, all else equal, a smaller hash would be epsilon
more performant. We also currently claim, in TLS 1.3, we prefer P-384
over P-256 which is off.
Instead order SHA-256 first, next the larger SHA-2 hashes, and leave
SHA-1 at the bottom. Within a hash, order ECDSA > RSA-PSS > RSA-PKCS1.
This has the added consequence that we will preferentially pair P-256
with SHA-256 in signatures we generate instead of larger hashes that get
truncated anyway.
Change-Id: If4aee068ba6829e8c0ef7948f56e67a5213e4c50
Reviewed-on: https://boringssl-review.googlesource.com/11821
Reviewed-by: Adam Langley <agl@google.com>
3a322f5e48