cert.go

// Copyright (c) ClaceIO, LLC
// SPDX-License-Identifier: Apache-2.0

package server

import (
	"crypto/ecdsa"
	"crypto/elliptic"
	"crypto/rand"
	"crypto/x509"
	"crypto/x509/pkix"
	"encoding/pem"
	"math/big"
	"os"
	"time"
)

func GenerateSelfSignedCertificate(certPath, keyPath string, validityDuration time.Duration) error {
	priv, err := ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
	if err != nil {
		return err
	}

	notBefore := time.Now()
	notAfter := notBefore.Add(validityDuration)

	template := x509.Certificate{
		SerialNumber:          big.NewInt(1),
		Subject:               pkix.Name{Organization: []string{"Clace Server"}},
		NotBefore:             notBefore,
		NotAfter:              notAfter,
		KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
		ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
		BasicConstraintsValid: true,
	}

	certDER, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
	if err != nil {
		return err
	}

	certFile, err := os.Create(certPath)
	if err != nil {
		return err
	}
	defer certFile.Close()

	err = pem.Encode(certFile, &pem.Block{Type: "CERTIFICATE", Bytes: certDER})
	if err != nil {
		return err
	}

	keyFile, err := os.Create(keyPath)
	if err != nil {
		return err
	}
	defer keyFile.Close()

	privBytes, err := x509.MarshalECPrivateKey(priv)
	if err != nil {
		return err
	}

	err = pem.Encode(keyFile, &pem.Block{Type: "EC PRIVATE KEY", Bytes: privBytes})
	if err != nil {
		return err
	}

	return nil
}