load_bignum
BIGNUM *load_bignum(const char *name);
a = load_bignum("ecdsa_1.param.priv");
b = load_bignum("ecdsa_1.param.pub");
a = load_bignum("rsa_1.param.n");
b = load_bignum("rsa_1.param.p");
c = load_bignum("rsa_1.param.q");