def sign(self,<EOL>digital_signature_algorithm,<EOL>crypto_alg,<EOL>hash_algorithm,<EOL>padding,<EOL>signing_key,<EOL>data):
if digital_signature_algorithm:<EOL><INDENT>(hash_alg, crypto_alg) = self._digital_signature_algorithms.get(<EOL>digital_signature_algorithm,<EOL>(None, None)<EOL>)<EOL><DEDENT>elif crypto_alg and hash_algorithm:<EOL><INDENT>hash_alg = self._encryption_hash_algorithms.get(<EOL>hash_algorithm, None<EOL>)<EOL><DEDENT>else:<EOL><INDENT>raise exceptions.InvalidField(<EOL>'<STR_LIT>'<EOL>'<STR_LIT>'<EOL>)<EOL><DEDENT>if crypto_alg == enums.CryptographicAlgorithm.RSA:<EOL><INDENT>try:<EOL><INDENT>key = self._create_RSA_private_key(signing_key)<EOL><DEDENT>except Exception:<EOL><INDENT>raise exceptions.InvalidField('<STR_LIT>'<EOL>'<STR_LIT>')<EOL><DEDENT><DEDENT>else:<EOL><INDENT>raise exceptions.InvalidField(<EOL>'<STR_LIT>'<EOL>)<EOL><DEDENT>if padding:<EOL><INDENT>padding_method = self._asymmetric_padding_methods.get(<EOL>padding, None<EOL>)<EOL><DEDENT>else:<EOL><INDENT>raise exceptions.InvalidField(<EOL>'<STR_LIT>'<EOL>)<EOL><DEDENT>if padding == enums.PaddingMethod.PSS:<EOL><INDENT>signature = key.sign(<EOL>data,<EOL>asymmetric_padding.PSS(<EOL>mgf=asymmetric_padding.MGF1(hash_alg()),<EOL>salt_length=asymmetric_padding.PSS.MAX_LENGTH<EOL>),<EOL>hash_alg()<EOL>)<EOL><DEDENT>elif padding == enums.PaddingMethod.PKCS1v15:<EOL><INDENT>signature = key.sign(<EOL>data,<EOL>padding_method(),<EOL>hash_alg()<EOL>)<EOL><DEDENT>else:<EOL><INDENT>raise exceptions.InvalidField(<EOL>"<STR_LIT>"<EOL>"<STR_LIT>".format(padding)<EOL>)<EOL><DEDENT>return signature<EOL>
Args:
    digital_signature_algorithm (DigitalSignatureAlgorithm): An
        enumeration specifying the asymmetric cryptographic algorithm
        and hashing algorithm to use for the signature operation. Can
        be None if cryptographic_algorithm and hash_algorithm are set.
    crypto_alg (CryptographicAlgorithm): An enumeration
        specifying the asymmetric cryptographic algorithm to use for
        the signature operation. Can be None if
        digital_signature_algorithm is set.
    hash_algorithm (HashingAlgorithm): An enumeration specifying the
        hash algorithm to use for the signature operation. Can be None
        if digital_signature_algorithm is set.
    padding (PaddingMethod): An enumeration specifying the asymmetric
        padding method to use for the signature operation.
    signing_key (bytes): The bytes of the private key to use for the
        signature operation.
    data (bytes): The data to be signed.

Returns:
    signature (bytes): the bytes of the signature data

Raises:
    CryptographicFailure: Raised when an error occurs during signature
        creation.
    InvalidField: Raised when an unsupported hashing or cryptographic
        algorithm is specified.