Re: randomdev entropy gathering is really weak

[Kris Kennaway]

On Sun, 23 Jul 2000, Jeroen C. van Gelderen wrote:

> > Well, a simple scheme which doesn't seem to suffer from any of the
> > vulnerabilities discussed in the schneier papers is to accumulate entropy
> > in a pool, and only return output when the pool is full. i.e. the PRNG
> > would either block or return 0 bytes of data, or a full pool's worth.
> 
> And you can make Yarrow do just that. Not very practical but
> you can do it. You effectively set Pg to 1/(2^(k/3)).

Oh, I missed this - thanks. It does introduce an extra overhead, namely
applying a generator gate with every output (since n < k and Pg < 1) and
then the full reseed with every k bits of output. ITYM Pg = k 2^(-k/3)
though - you want a maximum k bits of output, not 1. I'm not sure if the
current implementation will let you do this (since Pg < 1 here).

> Reseeds do not *have* to happen asynchronously as pointed out
> above.

Yeah, but they do in the current implementation (AFAICT).

Kris

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