def verify(self, signature, data):
        """
        Verify a signature using this key.

        @type signature: L{bytes}
        @param signature: The signature to verify.

        @type data: L{bytes}
        @param data: The signed data.

        @rtype: L{bool}
        @return: C{True} if the signature is valid.
        """
        if len(signature) == 40:
            # DSA key with no padding
            signatureType, signature = b'ssh-dss', common.NS(signature)
        else:
            signatureType, signature = common.getNS(signature)

        if signatureType != self.sshType():
            return False

        keyType = self.type()
        if keyType == 'RSA':
            k = self._keyObject
            if not self.isPublic():
                k = k.public_key()
            args = (
                common.getNS(signature)[0],
                data,
                padding.PKCS1v15(),
                hashes.SHA1(),
            )
        elif keyType == 'DSA':
            concatenatedSignature = common.getNS(signature)[0]
            r = int_from_bytes(concatenatedSignature[:20], 'big')
            s = int_from_bytes(concatenatedSignature[20:], 'big')
            signature = encode_dss_signature(r, s)
            k = self._keyObject
            if not self.isPublic():
                k = k.public_key()
            args = (signature, data, hashes.SHA1())

        elif keyType == 'EC':  # Pragma: no branch
            concatenatedSignature = common.getNS(signature)[0]
            rstr, sstr, rest = common.getNS(concatenatedSignature, 2)
            r = int_from_bytes(rstr, 'big')
            s = int_from_bytes(sstr, 'big')
            signature = encode_dss_signature(r, s)

            k = self._keyObject
            if not self.isPublic():
                k = k.public_key()

            keySize = self.size()
            if keySize <= 256:  # Hash size depends on key size
                hashSize = hashes.SHA256()
            elif keySize <= 384:
                hashSize = hashes.SHA384()
            else:
                hashSize = hashes.SHA512()
            args = (signature, data, ec.ECDSA(hashSize))

        try:
            k.verify(*args)
        except InvalidSignature:
            return False
        else:
            return True

        Verify a signature using this key.

        @type signature: L{bytes}
        @param signature: The signature to verify.

        @type data: L{bytes}
        @param data: The signed data.

        @rtype: L{bool}
        @return: C{True} if the signature is valid.
        
stackoverflow/venv/lib/python3.6/site-packages/twisted/conch/ssh/keys.py