If you are looking for PRNG conditioning code, feel free to snarf code from http://www.clark.net/pub/cme/html/ranno.html I'm assuming your new PRNG has enough state (more than 64 bits) that the 128-bit key (or later, larger keys) is worth its bits. I'm assuming you solve the problem of finding enough entropy bits for seeding the PRNG and considering how to keep as much of that entropy as possible in your PRNG seed (rather than, for a silly example, distilling it to an unsigned int for driving rand() ). For example, the state in ranG (from the giveaway code) or in ranM may not by itself lead to a secure PRNG, but when it drives a one-way function (e.g., ranH, ranD, ranN) the state is still serving a purpose. [ranG keeps 186 bytes of state while ranM keeps 32KB of state.] - Carl