4 ms·
> whereas a good puzzle cannot be impossible to crack. This is a very important distinction. It would be no fun if the cipher on a given cryptographer's tombst
by ythn 9y ago
> whereas a good puzzle cannot be impossible to crack.
This is a very important distinction. It would be no fun if the cipher on a given cryptographer's tombstone were created with a one-time pad.
- tlrobinson 9y agoWell, a certain type of person would find it fun to put an unsolvable puzzle on their own tombstone.
- ChrisSD 9y agoInterestingly a one time pad may be crackable. Its theoretical uncrackability is only true if a truly random number generator is used. Most cryptography is fine with urandom but a one time pad requires using something like radioactive decay to generate your pad. This is one reason (among many) why it's impractical for most crypto purposes.
- dlubarov 9y agoAssuming a flawless CSRNG, 128 bits of entropy is more than enough to withstand current attack power. It's hard to predict the future -- quantum computers employing Grover's algorithm could conceivably have 2x or more attack power per unit energy -- but 256 bits should be adequate for a long time. It's fine to use low-grade sources of entropy like timestamps as long as we have enough of it. I might only generate a few bits of actual entropy per second when I move my mouse in somewhat predictable arcs, but if I keep at it for a while, I'll generate 256 bits of entropy eventually.
- tptacek 9y agoRight, but his point is that you're not really talking about an OTP anymore, but rather a stream cipher that's as strong as the RNG. It will situationally be quite secure, but not the theoretical unbreakability of an OTP. OTPs are silly.
- mirimir 9y agoIf the one-time pad were public somewhere, how hard would it be to find it? Say, if it were indexed by Google?