ot::Crypto::HmacSha256::Finish() method

A reference to a `Hash` to output the calculated hash.

Finalizes the hash computation.

Calculates the ECDSA signature for a hashed message using the private key from `KeyPair`. Uses the deterministic digital signature generation procedure from RFC 6979.

Uses the `PublicKey` to verify the ECDSA signature of a hashed message.