BN_hex2bn
if (BN_hex2bn(&bn, hex) != len) {
static int BN_hex2bn(BIGNUM **, const char *);
n = BN_hex2bn(val, p + 2);
(void)BN_hex2bn(&modulus, HEXMODULUS);
(void)BN_hex2bn(&public, xpublic);
(void)BN_hex2bn(&secret, xsecret);
(void)BN_hex2bn(&modulus, HEXMODULUS);
int BN_hex2bn(BIGNUM **/*a*/, const char */*str*/);
BN_hex2bn(&a, cp);
BN_hex2bn(&a, cp);
BN_hex2bn(&a, argv[2]);