""" Calculate signature for provided digest
:param GOST3410Curve curve: curve to use
:param long prv: private key
:param digest: digest for signing
:type digest: bytes, 32 or 64 bytes
""" Calculate signature for provided digest
:param GOST3410Curve curve: curve to use
:param long prv: private key
:param digest: digest for signing
:type digest: bytes, 32 or 64 bytes