PRNG taking advantage of very large seed Can anyone suggest a good (CS)PRNG algorithm that takes advantage of having a very large (ideally arbitrarily large) seed? I'd like to use several kilobytes, perhaps several hundred kilobytes, of random data to generate up to a few dozen megabytes of PRNG output. The PRNG algorithms I'm aware of only take relatively small seeds: I'd like to make the most of the random input data I have.
The PRNG proposed by Barak and Halevi should be able to meet your needs and provide sufficient security. 

Their PRNG has an API of next and refresh. refresh takes an arbitrarily long string and uses it to update the internal state of the PRNG. next returns some number of random bytes (if more is needed, one can simply call next in succession).

They prove some very nice properties of their PRNG (which together define robustness of a PRNG), and give a concrete implementation.

The entire paper is definitely worth a read.