Re: fortuna API ?

On 04/27/2014 04:32 AM, Laurent Alebarde wrote:
> My use case is PRNG in the meaning that when I seed the generator with
> the same value, it produces the same pseudo-random numbers sequence. Can
> this be achieved with this library ? In other words, does this fortuna
> implementation a PRNG or a pseudo-TRNG ?

Fortuna has two parts: a generator and an accumulator.  The generator
produces a predictable series of values from a seed, and the accumulator
tries to reseed the generator with enough entropy that an attacker who
knows the internal RNG state can't follow the RNG state across the reseed.

You just want the generator.

>  Is there a documentation of this API somewhere please ?

It's not a public-facing API, so probably not.  I'm not aware of an
open-source Fortuna implementation with a public-facing generator API.
You might be able to lift generator code from a Fortuna implementation
and adapt it for your purposes.  If so, you'll want to separate out the
generator from the accumulator.

(Also note the comments at the top of rand-fortuna.c that it implements
something "Fortuna-like" and not Fortuna itself.)