libgo/go/crypto/tls/generate_cert.go

   1 // Copyright 2009 The Go Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style
   3 // license that can be found in the LICENSE file.
   4
   5 // +build ignore
   6
   7 // Generate a self-signed X.509 certificate for a TLS server. Outputs to
   8 // 'cert.pem' and 'key.pem' and will overwrite existing files.
   9
  10 package main
  11
  12 import (
  13         "crypto/rand"
  14         "crypto/rsa"
  15         "crypto/x509"
  16         "crypto/x509/pkix"
  17         "encoding/pem"
  18         "flag"
  19         "fmt"
  20         "log"
  21         "math/big"
  22         "net"
  23         "os"
  24         "strings"
  25         "time"
  26 )
  27
  28 var (
  29         host      = flag.String("host", "", "Comma-separated hostnames and IPs to generate a certificate for")
  30         validFrom = flag.String("start-date", "", "Creation date formatted as Jan 1 15:04:05 2011")
  31         validFor  = flag.Duration("duration", 365*24*time.Hour, "Duration that certificate is valid for")
  32         isCA      = flag.Bool("ca", false, "whether this cert should be its own Certificate Authority")
  33         rsaBits   = flag.Int("rsa-bits", 2048, "Size of RSA key to generate")
  34 )
  35
  36 func main() {
  37         flag.Parse()
  38
  39         if len(*host) == 0 {
  40                 log.Fatalf("Missing required --host parameter")
  41         }
  42
  43         priv, err := rsa.GenerateKey(rand.Reader, *rsaBits)
  44         if err != nil {
  45                 log.Fatalf("failed to generate private key: %s", err)
  46                 return
  47         }
  48
  49         var notBefore time.Time
  50         if len(*validFrom) == 0 {
  51                 notBefore = time.Now()
  52         } else {
  53                 notBefore, err = time.Parse("Jan 2 15:04:05 2006", *validFrom)
  54                 if err != nil {
  55                         fmt.Fprintf(os.Stderr, "Failed to parse creation date: %s\n", err)
  56                         os.Exit(1)
  57                 }
  58         }
  59
  60         notAfter := notBefore.Add(*validFor)
  61
  62         // end of ASN.1 time
  63         endOfTime := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
  64         if notAfter.After(endOfTime) {
  65                 notAfter = endOfTime
  66         }
  67
  68         template := x509.Certificate{
  69                 SerialNumber: new(big.Int).SetInt64(0),
  70                 Subject: pkix.Name{
  71                         Organization: []string{"Acme Co"},
  72                 },
  73                 NotBefore: notBefore,
  74                 NotAfter:  notAfter,
  75
  76                 KeyUsage:              x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
  77                 ExtKeyUsage:           []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
  78                 BasicConstraintsValid: true,
  79         }
  80
  81         hosts := strings.Split(*host, ",")
  82         for _, h := range hosts {
  83                 if ip := net.ParseIP(h); ip != nil {
  84                         template.IPAddresses = append(template.IPAddresses, ip)
  85                 } else {
  86                         template.DNSNames = append(template.DNSNames, h)
  87                 }
  88         }
  89
  90         if *isCA {
  91                 template.IsCA = true
  92                 template.KeyUsage |= x509.KeyUsageCertSign
  93         }
  94
  95         derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
  96         if err != nil {
  97                 log.Fatalf("Failed to create certificate: %s", err)
  98                 return
  99         }
 100
 101         certOut, err := os.Create("cert.pem")
 102         if err != nil {
 103                 log.Fatalf("failed to open cert.pem for writing: %s", err)
 104                 return
 105         }
 106         pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
 107         certOut.Close()
 108         log.Print("written cert.pem\n")
 109
 110         keyOut, err := os.OpenFile("key.pem", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
 111         if err != nil {
 112                 log.Print("failed to open key.pem for writing:", err)
 113                 return
 114         }
 115         pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})
 116         keyOut.Close()
 117         log.Print("written key.pem\n")
 118 }