On the Insecurity of Generalized (Rivest-Shamir-Adleman) - Advance and Adaptable Cryptosystem

Abstract

This paper explores the security claims of the Generalized (Rivest-Shamir-Adleman) - Advance and Adaptable Cryptosystem, in short the GRSA-AA cryptosystem. In the GRSA-AA design proposal, the public key n is defined as the multiplication of two large prime numbers, while the values of encryption key E and decryption key D are relying on the result of multiplying 2 k large prime numbers called N where n divides N. The GRSA-AA claimed that the brute force is necessary to break the cryptosystem even if the integer n was factored. Nevertheless, this paper aims to show that this scheme is insecure once n is factored. The mathematical proof is presented to show that it is easy to generate an alternative value to the private key D without brute-forcing, yet successfully break the system.