BN_pseudo_rand
if (!BN_pseudo_rand(btmp, SERIAL_RAND_BITS, 0, 0))
int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
if (!BN_pseudo_rand(y, BN_num_bits(p), 0, 0))
int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);