def from_key_bytes(cls, algorithm, key_bytes):
        """Builds a `Signer` from an algorithm suite and a raw signing key.

        :param algorithm: Algorithm on which to base signer
        :type algorithm: aws_encryption_sdk.identifiers.Algorithm
        :param bytes key_bytes: Raw signing key
        :rtype: aws_encryption_sdk.internal.crypto.Signer
        """
        key = serialization.load_der_private_key(data=key_bytes, password=None, backend=default_backend())
        return cls(algorithm, key)