OpenSSL::PKey::EC::Group.new

static VALUE ossl_ec_group_initialize(int argc, VALUE *argv, VALUE self)
{
    VALUE arg1, arg2, arg3, arg4;
    EC_GROUP *group;

    TypedData_Get_Struct(self, EC_GROUP, &ossl_ec_group_type, group);
    if (group)
        ossl_raise(rb_eRuntimeError, "EC_GROUP is already initialized");

    switch (rb_scan_args(argc, argv, "13", &arg1, &arg2, &arg3, &arg4)) {
    case 1:
        if (rb_obj_is_kind_of(arg1, cEC_GROUP)) {
            const EC_GROUP *arg1_group;

            GetECGroup(arg1, arg1_group);
            if ((group = EC_GROUP_dup(arg1_group)) == NULL)
                ossl_raise(eEC_GROUP, "EC_GROUP_dup");
        } else {
            BIO *in = ossl_obj2bio(&arg1);

            group = PEM_read_bio_ECPKParameters(in, NULL, NULL, NULL);
            if (!group) {
                OSSL_BIO_reset(in);
                group = d2i_ECPKParameters_bio(in, NULL);
            }

            BIO_free(in);

            if (!group) {
                const char *name = StringValueCStr(arg1);
                int nid = OBJ_sn2nid(name);

                ossl_clear_error(); /* ignore errors in d2i_ECPKParameters_bio() */
                if (nid == NID_undef)
                    ossl_raise(eEC_GROUP, "unknown curve name (%"PRIsVALUE")", arg1);

                group = EC_GROUP_new_by_curve_name(nid);
                if (group == NULL)
                    ossl_raise(eEC_GROUP, "unable to create curve (%"PRIsVALUE")", arg1);

                EC_GROUP_set_asn1_flag(group, OPENSSL_EC_NAMED_CURVE);
                EC_GROUP_set_point_conversion_form(group, POINT_CONVERSION_UNCOMPRESSED);
            }
        }

        break;
    case 4:
        if (SYMBOL_P(arg1)) {
            ID id = SYM2ID(arg1);
            EC_GROUP *(*new_curve)(const BIGNUM *, const BIGNUM *, const BIGNUM *, BN_CTX *) = NULL;
            const BIGNUM *p = GetBNPtr(arg2);
            const BIGNUM *a = GetBNPtr(arg3);
            const BIGNUM *b = GetBNPtr(arg4);

            if (id == s_GFp) {
                new_curve = EC_GROUP_new_curve_GFp;
#if !defined(OPENSSL_NO_EC2M)
            } else if (id == s_GF2m) {
                new_curve = EC_GROUP_new_curve_GF2m;
#endif
            } else {
                ossl_raise(rb_eArgError, "unknown symbol, must be :GFp or :GF2m");
            }

            if ((group = new_curve(p, a, b, ossl_bn_ctx)) == NULL)
                ossl_raise(eEC_GROUP, "EC_GROUP_new_by_GF*");
        } else {
             ossl_raise(rb_eArgError, "unknown argument, must be :GFp or :GF2m");
        }

        break;
    default:
        ossl_raise(rb_eArgError, "wrong number of arguments");
    }

    ASSUME(group);
    RTYPEDDATA_DATA(self) = group;

    return self;
}