Take the mappings for MD5 and SHA-224 values out of the code altogether. This
aligns with the current TLS 1.3 draft.
For MD5, this is a no-op. It is not currently possible to configure accepted
signature algorithms, MD5 wasn't in the hardcoded list, and we already had a
test ensuring we enforced our preferences correctly. MD5 also wasn't in the
default list of hashes our keys could sign and no one overrides it with a
different hash.
For SHA-224, this is not quite a no-op. The hardcoded accepted signature
algorithms list included SHA-224, so this will break servers relying on that.
However, Chrome's metrics have zero data points of servers picking SHA-224 and
no other major browser includes it. Thus that should be safe.
SHA-224 was also in the default list of hashes we are willing to sign. For
client certificates, Chromium's abstractions already did not allow signing
SHA-224, so this is a no-op there. For servers, this will break any clients
which only accept SHA-224. But no major browsers do this and I am not aware of
any client implementation which does such ridiculous thing.
(SHA-1's still in there. Getting rid of that one is going to take more effort.)
Change-Id: I6a765fdeea9e19348e409d58a0eac770b318e599
Reviewed-on: https://boringssl-review.googlesource.com/7020
Reviewed-by: Adam Langley <agl@google.com>
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