Abstract

Proposed paper gives a secure key exchange scheme using block upper triangular matrices of higher order. By using this method it is possible to generate keys of large orders without the need of large primes thereby avoiding the common ciphertext attacks. The element used for generating shared key is the element of (1, 3) block of the matrix which depends upon the elements of (1, 2) as well as on the (2, 3) blocks thereby increasing the hardness of the problem and providing greater security. Moreover our proposal is compared with the method proposed by Alvarez et al. (2009)

Key words: Block upper triangular matrices, public key cryptography, polynomial matrices, DH key exchange.