"Patrick J. LoPresti" writes:
I find it surprising that people so familiar with public key cryptography would be reassured by the argument, "Here, this algorithm has been examined by thousands and nobody has found a trap door." Public key cryptography demonstrates that it is possible, in principle, to construct an algorithm with a trap door that nobody else is *ever* going to find.
This is not correct as you have phrased it. Although it is not possible to find a decision proceedure for any non-trivial property of programs in general (whether it halts, for example) in practice well written code can be well understood and cannot conceal very much at all. In order to use public key cryptography to obfuscate a program as you suggest, you'd have to include huge tables of large numbers in it. Any idiot can observe the existance of such mysterious tables. Trying to conceal anything in cleanly written code is an enormous challenge, and one that has nothing to do with public key crypto per se. Incidently, this doesn't mean that you can't conceal things by producing subtle flaws in, for example, random number generation code. However, such flaws are hardly of the form "nobody else is *ever* going to find" -- anyone being extremely cautious in his analysis will find such flaws. .pm