Wildcat Crypto

With his “Pretty Good Privacy” (PGP), Phil Zimmermann launched the era of what I call Wildcat Crypto. Up to that point discussions on cryptology had focussed on whether DES, the US government standard, was secure and whether government involvement in its development might have jeopardized its security. To avoid government involvement, PGP used IDEA as alternative to DES for its bulk encryption. Yet IDEA is a close relative of DES and shares its weakness: small, constant-size blocks. True Wildcat Crypto calls for a radical departure in the form of blocks that are much larger, and moreover, vary in length under control of the key. In this article I trace the relevant history and outline my implementation of such a radical alternative.