I would discourage the integration of any PRNG algorithm into the code for three reasons. (1) libbitcoin passes this call to the operating system (through boost I believe). This allows integration with hardware random number generation. (2) Software cannot produce random numbers, so we discourage the use of even our own single API for this in any security context relating to bitcoin. Even bx allows all seeds to be input as arguments. We do not want to imply otherwise. (3) It is more code to maintain, and non-trivial.