Implementation of a public-key cryptosystem on the VAX 11/780

There is a growing need for secure transmission of messages and data via non-secure communication links. Most conventional cryptographic systems require the delivery, usually by couriers, of keys to sending and receiving locations. Public-key cryptosystems partially eliminate this requirement by allowing the sender's key to be made public.

Two public-key cryptosystems were considered in this thesis and one, the RSA system, was implemented on the VAX 11/780 computer. The various program segments were described in detail. Demonstrations of encoding-decoding operations were made and included as an Appendix. Generation of large prime numbers needed by the RSA system was described. Finally, it was concluded that, with minor improvements, the demonstration program could be upgraded to a commercially useful public-key cryptosystem.