forked from danderson/provision
/
cert.go
156 lines (138 loc) · 3.8 KB
/
cert.go
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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.
// Generate a self-signed X.509 certificate for a TLS server. Outputs to
// 'cert.pem' and 'key.pem' and will overwrite existing files.
package server
import (
"crypto/ecdsa"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"fmt"
"math/big"
"net"
"os"
"strconv"
"time"
)
var (
validFor = 365 * 24 * time.Hour
)
func publicKey(priv interface{}) (answer interface{}) {
switch k := priv.(type) {
case *rsa.PrivateKey:
answer = &k.PublicKey
case *ecdsa.PrivateKey:
answer = &k.PublicKey
}
return
}
func pemBlockForKey(priv interface{}) (answer *pem.Block, err error) {
switch k := priv.(type) {
case *rsa.PrivateKey:
answer = &pem.Block{Type: "RSA PRIVATE KEY", Bytes: x509.MarshalPKCS1PrivateKey(k)}
case *ecdsa.PrivateKey:
if b, err2 := x509.MarshalECPrivateKey(k); err2 != nil {
err = fmt.Errorf("Unable to marshal ECDSA private key: %v\n", err2)
} else {
answer = &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
}
}
return
}
func buildKeys(curveOrBits, certFile, keyFile string) error {
ips, err := net.InterfaceAddrs()
if err != nil {
return err
}
addrs := []string{"greg.fill.in", "localhost"}
for _, ip := range ips {
cidr := ip.String()
ip, _, err := net.ParseCIDR(cidr)
if err != nil || ip == nil {
continue
}
addrs = append(addrs, ip.String())
}
rsaBits := 2048
ecdsaCurve := "P384"
if curveOrBits[0] == 'P' {
ecdsaCurve = curveOrBits
} else if curveOrBits == "RSA" {
ecdsaCurve = "RSA"
} else {
ecdsaCurve = "RSA"
rsaBits, err = strconv.Atoi(curveOrBits)
if err != nil {
return err
}
}
var priv interface{}
switch ecdsaCurve {
case "RSA":
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:
return fmt.Errorf("Unrecognized elliptic curve: %q", ecdsaCurve)
}
if err != nil {
return fmt.Errorf("failed to generate private key: %s", err)
}
notBefore := time.Now()
notAfter := notBefore.Add(validFor)
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
return fmt.Errorf("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,
}
for _, h := range addrs {
if ip := net.ParseIP(h); ip != nil {
template.IPAddresses = append(template.IPAddresses, ip)
} else {
template.DNSNames = append(template.DNSNames, h)
}
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, publicKey(priv), priv)
if err != nil {
return fmt.Errorf("Failed to create certificate: %s", err)
}
certOut, err := os.Create(certFile)
if err != nil {
return fmt.Errorf("failed to open cert.pem for writing: %s", err)
}
pem.Encode(certOut, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
certOut.Close()
keyOut, err := os.OpenFile(keyFile, os.O_WRONLY|os.O_CREATE|os.O_TRUNC, 0600)
if err != nil {
return fmt.Errorf("failed to open key.pem for writing: %s", err)
}
if b, err := pemBlockForKey(priv); err != nil {
return err
} else {
pem.Encode(keyOut, b)
}
keyOut.Close()
return nil
}