The implementation of a cryptography-based secure office system
Christian Mueller-Schloer, Neal R. Wagner · 1982
A cryptography-based secure office system is discussed, including design criteria and a specific implementation. The system is intended to be practical, simple, and inexpensive, but also highly secure. The implementation uses a hybrid scheme of conventional (DES) and public-key (RSA) cryptography. Randomly generated DES keys encrypt messages and files, and the DES keys themselves and a one-way hash of the messages are encrypted and signed by RSA keys. The system provides secure electronic mail (including electronic registered mail and an electronic notary public), secure two-way channels, and secure user files. Timestamps and a special signed file of public keys help decrease the need for an online central authority involved in all transactions.