If I perturb kOrder in the malleability check, our and Wycheproof's
tests don't easily notice. This adds some tests with s above and below
the order. EdDSA hashes the public key with the message, which
frustrates constructing actual boundary cases. Instead, these inputs
were found by generating many signatures.
This isn't ideal, but it is sensitive to the most significant 32 bits.
Change-Id: I7fc03758ab97650d0e94478f355ea7085ae0559a
Reviewed-on: https://boringssl-review.googlesource.com/c/boringssl/+/44346
Commit-Queue: David Benjamin <davidben@google.com>
Commit-Queue: Adam Langley <agl@google.com>
Reviewed-by: Adam Langley <agl@google.com>