In order for two parties to share the same secret key, we studied the Diffie-Hellman protocol, whose security rests on the difficulty of the discrete logarithm problem.Īlthough this represents progress towards secure communication, it is particularly vulnerable to problems of authentication. The same key is used for both encryption and decryption, so we say it is a symmetric key cipher. The Vigenère cipher we studied uses a secret key for encrypting and decrypting messages. In the previous notebook, we studied a few basic ciphers together with Diffie-Hellman key exchange.
