/*
Copyright 2022 CAcert Inc.
SPDX-License-Identifier: Apache-2.0

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/

package helper

import (
	"crypto/rand"
	"fmt"
	"math/big"
)

// GenerateRandomSerial generates a random serial number to be used in X.509 certificates. The implementation is
// compliant to https://www.rfc-editor.org/rfc/rfc5280#section-4.1.2.2.
func GenerateRandomSerial() (*big.Int, error) {
	serial, err := rand.Int(rand.Reader, new(big.Int).Lsh(big.NewInt(1), 160)) //nolint:gomnd
	if err != nil {
		return nil, fmt.Errorf("could not generate random serial number: %w", err)
	}

	return serial, nil
}