Efficient key exchange and authentication protocols protecting weak secrets

We propose new key exchange and authentication protocols, which are efficient in protecting a poorly-chosen weak secret from guessing attacks, based on the use of a one-time pad and a strong one-way hash function. Cryptographic protocols assume that a strong secret should be shared between communication participants for authentication in the light of an ever-present threat of guessing attacks. Cryptographically long secret would be better for security only if ordinary users could remember it. But most users choose an easy-to-remember password as a secret and such a weak secret can be guessed easily. In our previous work, we made much of introducing a basic concept and its application. In this paper, we describe our idea in more detail and propose more protocols which correspond to variants of our basic protocol using well-defined notations. Formal verification and efficiency comparison of the proposed protocols are also presented. By our scheme the password guessing attacks are defeated efficiently, and a session key is exchanged and participants are authenticated securely.