key_exchange.py

def key_exchange(self, client_pub_key) -> tuple[bool, dict]:
    try:
        _salt = os.urandom(16)
        shared_secret = self.get_shared_secret(client_pub_key)
        session_key = self.get_shared_secret_kdf(_salt, shared_secret)
        keyId = self.generate_kid(session_key)
        kex_result = {
            'KeyId': keyId,
            'Salt': _salt.hex(),
            'ServerPublicKey': self.serv_priv_key.public_key().public_bytes(
                encoding = serialization.Encoding.DER,
                format = serialization.PublicFormat.SubjectPublicKeyInfo
            ).hex()
        }
        return (True, kex_result)
    except ValueError:
        return (False, msg_config.KEX_INVALID_DER)
    except UnsupportedAlgorithm:
        return (False, msg_config.KEX_INVALID_ALG)