do-it-yourself encryption Really don't know where to put this, so thought I'd ask all the fine folks here and see if I get a response. One of the curses of being widely read is that sometimes you remember the subject but neither content nor location of something you read once and would really like to find out where it can be found again. I know I've read several 'schemes' for doing encryption(high security, no kiddy stuff, the kind it takes a wealthy adversary centuries to crack) in your head or with a few notes on a piece of paper(which if compromised mean nothing cryptanalytically) but cannot find it anywhere. Any of this ring a bell for someone who can provide a url or summary? The kind of stuff I'm looking for is probably symmetric(tho assymetric would be great and can require any kind of printout or out-of-mind assistance as long as nothing is given away cryptanalytically on any of it. If anyone remembers anything like this I'd love to hear about it.