Hej! I've finally got the time to read "Cyphernomicon", and in chapter 5 (Cryptology) and 17 (The Future) I found this, which I think looks interesting, since I'm interested in computational topology. 5.5.9. Miscellaneous Abstract Ideas [...stuff deleted...] - links to knot theory 17.10.3. Ciphers are somewhat like knots...the right sequence of moves unties them, the wrong sequence only makes them more tangled. ("Knot theory" is becoming a hot topic in math and physics (work of Vaughn Jones, string theory, etc.) and I suspect there are some links between knot theory and crypto.) Has any work been done along those lines? I did some searches with AltaVista, but I only found Cyphernomicon... /Krister