Abstract

Public key infrastructure is used for strong encryption and decryption in large applications across the internet. If the private key is known to hackers, then all previous encrypted received messages can be decrypted. In this paper, a scheme that uses triple keys for encryption/decryption is proposed to overcome several attacks that are possible on RSA algorithm. This scheme is based on the modified RSA algorithm by supporting three distinct prime numbers used for encryption/decryption. These numbers are used to generate three encryption/decryption keys that are coprime with the gcd (ϕ(p, q, r) = (p-1)(q-1)(r-1)). These keys are the server’s private key (p), the secure user’s private key (q), and the server’s public key (r). Hackers, who manage to get a copy of the server’s private key or are able to crack the server’s public key, cannot decrypt the messages exchanged between the user and the server as they need to know the user’s private key. This key is only known to initiators who have the authentication parameters. Therefore, hackers are unable to crack the message encrypted using the proposed technique. In addition, cryptanalyst would require double the time to break the system compared to RSA as revealed by the obtained results.

Key words: Modified RSA; Public key infrastructure; Asymmetric encryption; Security; Cryptography.