private_key=

static VALUE ossl_ec_key_set_private_key(VALUE self, VALUE private_key)
{
    EC_KEY *ec;
    BIGNUM *bn = NULL;

    Require_EC_KEY(self, ec);
    if (!NIL_P(private_key))
        bn = GetBNPtr(private_key);

    switch (EC_KEY_set_private_key(ec, bn)) {
    case 1:
        break;
    case 0:
        if (bn == NULL)
            break;
    default:
        ossl_raise(eECError, "EC_KEY_set_private_key");
    }

    return private_key;
}