Visit http://patent.womplex.ibm.com/ and learn all about it. I don't claim to know much about cryptography, but these sure look like garbage to me.
5,307,412, "Random Coding Cipher System and Method" 5,335,280, "Random Sum Cipher System and Method"
Sender and receiver share what should be a one-time pad, with a trailer on each encrypted each message saying where in the pad to start next time. I don't see any advantage compared to the standard approach of using your pad sequentially other than that this scheme makes it harder to tell when it's used up.
5,533,128, "Pseudo-Random Transposition Cipher System and Method"
Sender and receiver initialize their set of pseudo-random number generators to the same secret thing and use the generated streams of digits to control a transposition cipher. Sheesh. I didn't look at the full patents, just the summaries, so I may have missed something. Please look at the patents themselves before flaming. The IBM web site is a fabulous resource -- they have a CD-ROM farm that provides scanned page images of all the patents issued for the past several decades. Also check out the gallery of obscure patents, e.g., the human slingshot, and the microprocessor controlled belching beer mug. Regards, John Levine, johnl@iecc.com, Village Trustee, Trumansburg NY Primary Perpetrator of "The Internet for Dummies" and Information Superhighwayman wanna-be, http://iecc.com/johnl