BN_generate_prime_ex
if (!BN_generate_prime_ex(bn, prime_config.bits,
if (!BN_generate_prime_ex(ret->p, prime_len, 1, t1, t2, cb))
if (!BN_generate_prime_ex(rsa->p, bitsp, 0, NULL, NULL, cb))
if (!BN_generate_prime_ex(rsa->q, bitsq, 0, NULL, NULL,
int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe, const BIGNUM *add,