new

static VALUE
ossl_dh_initialize(int argc, VALUE *argv, VALUE self)
{
    EVP_PKEY *pkey;
    DH *dh;
    int g = 2;
    BIO *in;
    VALUE arg, gen;

    GetPKey(self, pkey);
    if(rb_scan_args(argc, argv, "02", &arg, &gen) == 0) {
      dh = DH_new();
    }
    else if (FIXNUM_P(arg)) {
        if (!NIL_P(gen)) {
            g = NUM2INT(gen);
        }
        if (!(dh = dh_generate(FIX2INT(arg), g))) {
            ossl_raise(eDHError, NULL);
        }
    }
    else {
        arg = ossl_to_der_if_possible(arg);
        in = ossl_obj2bio(arg);
        dh = PEM_read_bio_DHparams(in, NULL, NULL, NULL);
        if (!dh){
            (void)BIO_reset(in);
            dh = d2i_DHparams_bio(in, NULL);
        }
        BIO_free(in);
        if (!dh) ossl_raise(eDHError, NULL);
    }
    if (!EVP_PKEY_assign_DH(pkey, dh)) {
        DH_free(dh);
        ossl_raise(eDHError, NULL);
    }
    return self;
}