new

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

    TypedData_Get_Struct(self, ossl_ec_group, &ossl_ec_group_type, ec_group);
    if (ec_group->group != NULL)
        ossl_raise(rb_eRuntimeError, "EC_GROUP is already initialized");

    switch (rb_scan_args(argc, argv, "13", &arg1, &arg2, &arg3, &arg4)) {
    case 1:
        if (SYMBOL_P(arg1)) {
            const EC_METHOD *method = NULL;
            ID id = SYM2ID(arg1);

            if (id == s_GFp_simple) {
                method = EC_GFp_simple_method();
            } else if (id == s_GFp_mont) {
                method = EC_GFp_mont_method();
            } else if (id == s_GFp_nist) {
                method = EC_GFp_nist_method();
#if !defined(OPENSSL_NO_EC2M)
            } else if (id == s_GF2m_simple) {
                method = EC_GF2m_simple_method();
#endif
            }

            if (method) {
                if ((group = EC_GROUP_new(method)) == NULL)
                    ossl_raise(eEC_GROUP, "EC_GROUP_new");
            } else {
                ossl_raise(rb_eArgError, "unknown symbol, must be :GFp_simple, :GFp_mont, :GFp_nist or :GF2m_simple");
            }
        } else if (rb_obj_is_kind_of(arg1, cEC_GROUP)) {
            const EC_GROUP *arg1_group;

            SafeRequire_EC_GROUP(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);

                (void)ERR_get_error();
                if (nid == NID_undef)
                    ossl_raise(eEC_GROUP, "unknown curve name (%s)", name);

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

                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");
    }

    if (group == NULL)
        ossl_raise(eEC_GROUP, "");

    ec_group->group = group;

    return self;
}