Re: /dev/random - using up entropy?

[Wei Dai <weidai@eskimo.com>]

On Sat, 4 Nov 1995, Bill Stewart wrote:

> Most of the designs I've seen look like this:
>         A Reservoir of entropy R = R1....Rn, where n is large, 1024 or 4096
>         An input stream I = I1....Ik, which is mixed into R
>         A mixing function F which is used to mix R <= F(R,I) 
>                 for some chunk of I, possibly empty.
>         A hash function H, typically MD5.
>         An output O = O1...Om = H(R), and E gets mixed after every output.
>                 (These are capital-o, not zero...)

I believe PGP uses this approach.  An implementation of it can also be
found in Crypto++ as randpool.cpp.