Signs digest, the digest of the signed attributes, with the signer's private key.
public byte[] SignDigest(ReadOnlySpan<byte> digest, HashAlgorithmName digestAlgorithm)
The digest to sign.
The algorithm digest was computed with.
ISO 32000-2 §12.8.3.3; RFC 5652 §5.5. Throw to abandon the signature; nothing is written then.