Key Establishment Using Signcryption Techniques

Abstract

Possibly the most useful branch of public key cryptography is key establishment. After all, it is the problem of symmetric key distribution that prompted Diffie and Hellman to propose the notion of public key cryptography in the first place [74]. The basic idea behind a key establishment protocol is that two (or more) parties should exchange cryptographic messages in such a way that, at the end of the protocol, they both know a shared key—typically a bitstring of a fixed length that can be used with a symmetric cryptosystem. It is imperative that no party other than those actively participating in the key establishment protocol (and perhaps one or more trusted third parties) can obtain any information about this shared secret key. We also usually require that, at the end of a successful protocol execution, each party is convinced of the identity of the other party. Hence, the basic security notions we require from a key establishment protocol are those of confidentiality and entity authentication .