Hi :) Josh (and the manual) is right -- don't use Guile's RNG for security-sensitive purposes. Mostly it's just for games, monte-carlo simulations and the like. I wish it were a CSPRNG but it's not; oh well.
The quality of the PRNG is a separate issue. MWC could be improved, but JS impls at least moved to xorshift128+ or something like that. Anyway a separate topic entirely. For sufficiently random sequences of bytes for cryptographic purposes, I recommend get-bytevector-n on /dev/urandom. Andy
