On Wednesday, 11 June 2014 at 06:41:34 UTC, Joseph Rushton
Done :) ... if I get a response, I'll make sure to incorporate
Great, let me know how that goes. :-)
Well, the ultimate conclusion of the conversation with the guy is
1. ISAAC probably isn't cryptographically secure. Despite not
having found any attacks, it just isn't proof of security. It's
not been looked at enough to really approve of its usage for that
purpose (I'm kind of agreeing with this)
2. ISAAC in his opinion probably isn't appropriate for non secure
uses for much the same reason.
I don't agree with that because everything I've seen for ISAAC
shows that it has some really good statistical properties. Even
if it's not cryptographically secure, it appears to produce
"better" pseudorandom numbers to me than something like MT19937
or Well* (and ISAAC is really fast after the initial cost has
been paid back)
Ultimately, I think ISAAC (and ISAAC-64) _will_ get more scrutiny
in the future as it's a PRNG used in Rust, for instance. I would
not suggest it for default purposes, but I think having it as a
non-crypto RNG in D wouldn't be a bad idea for those who want to
choose to use it.
3. Better ideas for crypto PRNGs are AES-CTR or Salsa20.
I agree with this approach for the crypto section of std.random.
I'd also suggest Blum Blum Shub as another thing to add. It's
awfully slow, but it's probably one of the few PRNGs that is
"provably strong" (that is, it's been reduced to a known hard
Also, he suggested me to refer to a presentation he made last
I've gone through it and it looks like excellent reference
material. Note slide 76 saying: "Don't use RaaS (things like
random.org) -> random bits may be shared or reused". Also, it has
suggestions for entropy on Windows (CryptGenRandom) which is
something that will be necessary as well.
Overall, very enlightening.