Rick Busdiecker <rfb@lehman.com> writes:

it is quite easy to write cryptographic algorithms that use very large numbers without adding extra support. The downside is that the language is

Yup. I've written some code that generates large numbers, tests for primality and does RSA. The basic RSA enclode is just (mod-expt m e n) and decrypt is (mod-expt c d n) where mod-expt is just an optimized version of (mod (expt x p) n), ala Schneier, page 200 (1st edition).

Actually, there is a modexpt (and a Fermat test) implementation in chapter 1 of Abelson/Sussman, with a footnote mentioning cryptography. I do wonder if they have an export license... :)