[Rebased and tests added by davidben.]
In doing so, regenerate the test RSA certificate to be 2048-bit RSA.
RSA-PSS with SHA-512 is actually too large for 1024-bit RSA. Also make
the sigalg test loop test versions that do and don't work which subsumes
the ecdsa_sha1 TLS 1.3 test.
For now, RSA-PKCS1 is still allowed because NSS has yet to implement
RSA-PSS and we'd like to avoid complicated interop testing.
Change-Id: I686b003ef7042ff757bdaab8d5838b7a4d6edd87
Reviewed-on: https://boringssl-review.googlesource.com/8613
Reviewed-by: David Benjamin <davidben@google.com>
Initial fork from f2d678e6e89b6508147086610e985d4e8416e867 (1.0.2 beta).
(This change contains substantial changes from the original and
effectively starts a new history.)
