OpenSSL::BN#+@

static VALUE
ossl_bn_uplus(VALUE self)
{
    VALUE obj;
    BIGNUM *bn1, *bn2;

    GetBN(self, bn1);
    obj = NewBN(cBN);
    bn2 = BN_dup(bn1);
    if (!bn2)
        ossl_raise(eBNError, "BN_dup");
    SetBN(obj, bn2);

    return obj;
}