4 ms·
Right. Hence "nothing up my sleeve" numbers. It's hard to fit a backdoor into Pi.
by cperciva 11y ago
Right. Hence "nothing up my sleeve" numbers. It's hard to fit a backdoor into Pi.
- baby 11y agoWhy did you choose Pi? And not e? (see what I'm doing?)
- tptacek 11y agoBecause pi is the simplest constant that has already been used as a magic constant in other cryptographic algorithms. Next question?
- baby 11y agoThat's completely not true. Example sha-1: > The constant values used are chosen to be nothing up my sleeve numbers: the four round constants k are 230 times the square roots of 2, 3, 5 and 10. The first four starting values for h0 through h3 are the same with the MD5 algorithm, and the fifth (for h4) is similar.
- tptacek 11y ago230 times the square roots of 2, 3, 5 and 10 versus the first N digits of Pi, minus the leading 3 (what Blowfish used).
- baby 11y agoother examples: https://news.ycombinator.com/item?id=11161841 https://news.ycombinator.com/item?id=11161841
- tptacek 11y agoLook at the BLAKE example there: it's simply the leading digits of pi. The rest of the examples seem like they prove my point. 1/pi? sin(n)? First N primes? Cubes of first N primes? I agree! Super sketchy! Why would you use any of those? Just use pi.
- baby 11y agoWAT, there was no pi in that list
- pbsd 11y agoYou probably don't want to use BLAKE as the poster child for this argument, since it uses two sets of constants of distinct provenance: the initialization vector, which uses the same constants as SHA-2, i.e., the square roots of the first 8 primes, and the constants used in the compression function, which are indeed the expansion of pi. BLAKE2 got rid of the pi constants.
- wglb 11y agoI used to think so until I read Carl Sagan's Contact.