Key Recovery Attack on a Knapsack Public Key Cryptosystem

Abstract

A new knapsack public key cryptosystem is crypt analyzed. The cryptanalytic attack uses the Euclidean algorithm to obtain the greatest common divisor of some integers, and thus recovers the modulus. Then the attack reconstructs the multiplier by solving a linear congruence. Therefore, all the secret keys can be retrieved in polynomial time. Hence, the public key cryptosystem is insecure.