Secure communications over insecure channels

TLDR

Traditional cryptographic security requires secret key transmission before secure messaging, and further research into key selection over open channels is promising. This paper shows that it is possible to select a key over open communications channels in such a fashion that communications security can be maintained. The method forces an adversary to expend work that grows quadratically with the effort required by the communicants to select the key. The method provides a logically new kind of protection against the passive eavesdropper.

Abstract

According to traditional conceptions of cryptographic security, it is necessary to transmit a key, by secret means, before encrypted massages can be sent securely. This paper shows that it is possible to select a key over open communications channels in such a fashion that communications security can be maintained. A method is described which forces any enemy to expend an amount of work which increases as the square of the work required of the two communicants to select the key. The method provides a logically new kind of protection against the passive eavesdropper. It suggests that further research on this topic will be highly rewarding, both in a theoretical and a practical sense.