CRYPTOGRAPHIC REDUNDANCY AND MIXING FUNCTIONS

This paper studies the use of structures based on error correcting cod es to achieve secrecy rather than error control, In many cases, howeve r, the same code can achieve both error control and secrecy, The first section of the paper describes an optimal construction for combining multiple semi-secure channels, e.g., a bundle of fiber-optic cables or reels of tape sent by independent couriers, into a single channel wit h much higher security. The remainder of the paper shows how mixing an d scrambling functions formed from error correcting codes can be used to enhance the security of trunked communications circuits and convent ional cryptographic systems which depend, for their security, on unpro ven assertions about computational difficulty.