jgk@osc.COM (Joe Keane) (05/02/91)
In article <GUEST.91Apr29180522@geech.ai.mit.edu> guest@geech.ai.mit.edu (Guest Account) writes: >For those of you who have heard of VCR PLUS+, does anyone know how the >date, channel, start time and stop time are encoded into the program >number? Here are examples: I'm curious about this too. I doubt these guys hired professional cryptographers to design their encoding scheme, so i bet it's not hard to break. Does anyone have information on the scheme? Failing that, does anyone have a large number of examples they'd like to send me? -- Joe Keane, amateur cryptographer jgk@osc.com (...!uunet!stratus!osc!jgk)
ts@cup.portal.com (Tim W Smith) (05/03/91)
Why do you assume that they did not hire cryptographers? The company that makes this thing is in Pasadena, California. The only rational reason a company making a gadget like this would be in Pasadena would be if they are from Caltech or JPL or both. Assuming that they want to protect these codes, I would expect people from Caltech or JPL to be smart enough to either hire a cryptographer or to learn enough about cryptography themselves to make this a hard problem. Tim Smith ps: I think that they can make this problem very hard without using sophisticated cryptographic methods. For instance, with 100K or so of ROM (quite feasible in a device this size), they could simply use a table lookup scheme as part of the encoding process. If these tables are well constructed, to break this you might either have to have a nearly complete set of encodings, or take the device apart and disassemble the software.