Public key cryptosystem and a key exchange protocol using tools of non-abelian group

Abstract. Public Key Cryptosystems assure privacy as well as integrity of the transactions between two parties. The sizes of the keys play an important role. The larger the key the harder is to crack a block of encrypted data. We propose a new public key cryptosystem and a Key Exchange Protocol based on the generalization of discrete logarithm problem using Non-abelian group of block upper triangular matrices of higher order. The proposed cryptosystem is efficient in producing keys of large sizes without the need of large primes. The security of both the systems relies on the difficulty of discrete logarithms over finite fields.