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authorDimitri Sokolyuk <demon@dim13.org>2016-02-21 00:10:34 +0100
committerDimitri Sokolyuk <demon@dim13.org>2016-02-21 00:10:34 +0100
commita85cc677319e2c0a01c106baa3061755742dc7df (patch)
treedbcb24e4b66b5a20a9f991a25892af8205c51597
Initial import
-rw-r--r--generate_cert.go159
1 files changed, 159 insertions, 0 deletions
diff --git a/generate_cert.go b/generate_cert.go
new file mode 100644
index 0000000..deb7da8
--- /dev/null
+++ b/generate_cert.go
@@ -0,0 +1,159 @@
+// 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 (
+ "crypto/ecdsa"
+ "crypto/elliptic"
+ "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. Ignored if --ecdsa-curve is set")
+ ecdsaCurve = flag.String("ecdsa-curve", "", "ECDSA curve to use to generate a key. Valid values are P224, P256, P384, P521")
+)
+
+func publicKey(priv interface{}) interface{} {
+ switch k := priv.(type) {
+ case *rsa.PrivateKey:
+ return &k.PublicKey
+ case *ecdsa.PrivateKey:
+ return &k.PublicKey
+ default:
+ return nil
+ }
+}
+
+func pemBlockForKey(priv interface{}) *pem.Block {
+ switch k := priv.(type) {
+ case *rsa.PrivateKey:
+ return &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
+ case *ecdsa.PrivateKey:
+ b, err := x509.MarshalECPrivateKey(k)
+ if err != nil {
+ fmt.Fprintf(os.Stderr, "Unable to marshal ECDSA private key: %v", err)
+ os.Exit(2)
+ }
+ return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
+ default:
+ return nil
+ }
+}
+
+func main() {
+ flag.Parse()
+
+ if len(*host) == 0 {
+ log.Fatalf("Missing required --host parameter")
+ }
+
+ var priv interface{}
+ var err error
+ switch *ecdsaCurve {
+ case "":
+ priv, err = rsa.GenerateKey(rand.Reader, *rsaBits)
+ case "P224":
+ priv, err = ecdsa.GenerateKey(elliptic.P224(), rand.Reader)
+ case "P256":
+ priv, err = ecdsa.GenerateKey(elliptic.P256(), rand.Reader)
+ case "P384":
+ priv, err = ecdsa.GenerateKey(elliptic.P384(), rand.Reader)
+ case "P521":
+ priv, err = ecdsa.GenerateKey(elliptic.P521(), rand.Reader)
+ default:
+ fmt.Fprintf(os.Stderr, "Unrecognized elliptic curve: %q", *ecdsaCurve)
+ os.Exit(1)
+ }
+ if err != nil {
+ log.Fatalf("failed to generate private key: %s", err)
+ }
+
+ 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)
+
+ serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
+ serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
+ if err != nil {
+ log.Fatalf("failed to generate serial number: %s", err)
+ }
+
+ template := x509.Certificate{
+ SerialNumber: serialNumber,
+ 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, publicKey(priv), priv)
+ if err != nil {
+ log.Fatalf("Failed to create certificate: %s", err)
+ }
+
+ certOut, err := os.Create("cert.pem")
+ if err != nil {
+ log.Fatalf("failed to open cert.pem for writing: %s", err)
+ }
+ 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, pemBlockForKey(priv))
+ keyOut.Close()
+ log.Print("written key.pem\n")
+}