github.com/varialus/godfly@v0.0.0-20130904042352-1934f9f095ab/src/pkg/crypto/tls/generate_cert.go (about)

     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  }