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// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
// +build ignore
// Generate a self-signed X.509 certificate for a TLS server. Outputs to
// 'cert.pem' and 'key.pem' and will overwrite existing files.
package main
import (
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"flag"
"fmt"
"log"
"math/big"
"net"
"os"
"strings"
"time"
)
var (
host = flag.String("host", "", "Comma-separated hostnames and IPs to generate a certificate for")
validFrom = flag.String("start-date", "", "Creation date formatted as Jan 1 15:04:05 2011")
validFor = flag.Duration("duration", 365*24*time.Hour, "Duration that certificate is valid for")
isCA = flag.Bool("ca", false, "whether this cert should be its own Certificate Authority")
rsaBits = flag.Int("rsa-bits", 2048, "Size of RSA key to generate")
)
func main() {
flag.Parse()
if len(*host) == 0 {
log.Fatalf("Missing required --host parameter")
}
priv, err := rsa.GenerateKey(rand.Reader, *rsaBits)
if err != nil {
log.Fatalf("failed to generate private key: %s", err)
return
}
var notBefore time.Time
if len(*validFrom) == 0 {
notBefore = time.Now()
} else {
notBefore, err = time.Parse("Jan 2 15:04:05 2006", *validFrom)
if err != nil {
fmt.Fprintf(os.Stderr, "Failed to parse creation date: %s\n", err)
os.Exit(1)
}
}
notAfter := notBefore.Add(*validFor)
// end of ASN.1 time
endOfTime := time.Date(2049, 12, 31, 23, 59, 59, 0, time.UTC)
if notAfter.After(endOfTime) {
notAfter = endOfTime
}
template := x509.Certificate{
SerialNumber: new(big.Int).SetInt64(0),
Subject: pkix.Name{
Organization: []string{"Acme Co"},
},
NotBefore: notBefore,
NotAfter: notAfter,
KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
hosts := strings.Split(*host, ",")
for _, h := range hosts {
if ip := net.ParseIP(h); ip != nil {
template.IPAddresses = append(template.IPAddresses, ip)
} else {
template.DNSNames = append(template.DNSNames, h)
}
}
if *isCA {
template.IsCA = true
template.KeyUsage |= x509.KeyUsageCertSign
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, &priv.PublicKey, priv)
if err != nil {
log.Fatalf("Failed to create certificate: %s", err)
return
}
certOut, err := os.Create("cert.pem")
if err != nil {
log.Fatalf("failed to open cert.pem for writing: %s", err)
return
}
pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
certOut.Close()
log.Print("written cert.pem\n")
keyOut, err := os.OpenFile("key.pem", os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
log.Print("failed to open key.pem for writing:", err)
return
}
pem.Encode(keyOut, &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(priv)})
keyOut.Close()
log.Print("written key.pem\n")
}
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