in reply to Re: Cryptographically Secure Psuedorandom Number Genergator - PRNG?
in thread Cryptographically Secure Psuedorandom Number Genergator - PRNG?

That page itself links to a perl version of the ISAAC code: http://burtleburtle.net/bob/rand/randperl.txt.

But the code is trivial enough that exposing the C code via an XS or Inline module should be a pretty straightforward path to retaining the speed of C if that's an issue.

Hugo

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Re^3: Cryptographically Secure Psuedorandom Number Genergator - PRNG?
by radiantmatrix (Parson) on Jun 10, 2005 at 17:21 UTC

    Aha! Thank you! I'm working producing a module for that code that can provide a drop-in replacement to the default rand(). I will probably publish it in the Monestary first, then work on submitting to CPAN (which will be a new experience for me, and so might take some time).

    As I mention in my new update to the parent node, however, I also need a cross-platform (at least *NIX and Win) method to generate a seed. For ISAAC specifically, I would want at least one and no more than 256 32-bit values with which to seed the PRNG. Any thoughts?

    Yoda would agree with Perl design: there is no try{}

[reply]

      Not sure how best to seed if you can't rely on /dev/random. I've seen a colleague on Mac trying to generate an ssh (or maybe PGP) key and being required to "type randomly for long enough" to generate random bits for security; not sure what application that was though.

      So maybe the thing you need to look at is the device driver code for /dev/random. Everything2 has some interesting information about what it does, and for Linux the source should be in drivers/char/random.c.

      Hugo

[reply]

      You don't like the random bytes from a random file idea?

      Examine what is said, not who speaks -- Silence betokens consent -- Love the truth but pardon error.
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[reply]

        I like the idea, but I don't think it is sufficient; I can't guarantee, in a cross-platform way, where to find a set of files that changes fast enough.

        What if someone uses this module as a PRNG to generate a single random password in a script -- but that script is called very quickly on a high-volume web server. I can find fast-changing files on Windows and Linux, but what about other platforms?

        Also, the idea of using 'random' bytes from a 'random' file when I don't yet have a seed for a random-number generator seems like a bit of a chicken-and-egg problem, don't you think? ;-)

        Yoda would agree with Perl design: there is no try{}

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