Specialised attack on Chor-Rivest public key cryptosystem

The Chor-Rivest public key cryptosystem (PKC) is a knapsack-type crypto-system based on arithmetic in finite fields GF (p^h). It uses large fields, such as GF (197²⁴), where it is possible to compute discrete logarithms, which must be carried out at system configuration. The author presents a ´specialised attack´ on the Chor-Rivest PKC which exploits an inherent algebraic property of the system.