p521: initial ecdsa
support with FIPS 186-4 test vectors
#956
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Initial
ecdsa
feature and test vectors to ensure it's working.Due to P-521's unusual modulus size, we can't use the upstream
ecdsa::{SigningKey, VerifyingKey}
types (although we are able to use the generic implementation of ECDSA). Theecdsa
crate currently includes bounds for the digest size in several places, including the RFC6979 implementation, which are incompatible with P-521, which uses a 66-byte serialized scalar size along with SHA-521, which emits a 64-byte digest. Fixing that will require breaking changes to theecdsa
crate.To work around this, newtypes for
SigningKey
andVerifyingKey
have been added. They largely wrap the inner types, but don't use RFC6979 and instead randomly generateR
each time signing is performed (using an on-by-defaultgetrandom
feature which enablesrand_core::OsRng
).FIPS 186-4 test vectors adapted from
SigGen.txt
in186-4ecdsatestvectors.zip
from:https://csrc.nist.gov/projects/cryptographic-algorithm-validation-program/digital-signatures
cc @MasterAwesome