// 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. // 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 ( "big" "crypto/x509/pkix" "crypto/rand" "crypto/rsa" "crypto/x509" "encoding/pem" "flag" "log" "os" "time" ) var hostName *string = flag.String("host", "127.0.0.1", "Hostname to generate a certificate for") func main() { flag.Parse() priv, err := rsa.GenerateKey(rand.Reader, 1024) if err != nil { log.Fatalf("failed to generate private key: %s", err) return } now := time.Seconds() template := x509.Certificate{ SerialNumber: new(big.Int).SetInt64(0), Subject: pkix.Name{ CommonName: *hostName, Organization: []string{"Acme Co"}, }, NotBefore: time.SecondsToUTC(now - 300), NotAfter: time.SecondsToUTC(now + 60*60*24*365), // valid for 1 year. SubjectKeyId: []byte{1, 2, 3, 4}, KeyUsage: x509.KeyUsageKeyEncipherment | x509.KeyUsageDigitalSignature, } 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") }