/
sslcert.go
153 lines (137 loc) · 4.05 KB
/
sslcert.go
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// Package sslcert contains a reworked version of https://golang.org/src/crypto/tls/generate_cert.go
package sslcert
import (
"bufio"
"bytes"
"crypto/ecdsa"
"crypto/ed25519"
"crypto/elliptic"
"crypto/rand"
"crypto/rsa"
"crypto/x509"
"crypto/x509/pkix"
"encoding/pem"
"errors"
"fmt"
"math/big"
"net"
"strings"
"time"
)
func pubKey(priv interface{}) interface{} {
switch k := priv.(type) {
case *rsa.PrivateKey:
return &k.PublicKey
case *ecdsa.PrivateKey:
return &k.PublicKey
case ed25519.PrivateKey:
return k.Public().(ed25519.PublicKey)
default:
return nil
}
}
func Generate(options Options) (privateKey, publicKey []byte, err error) {
if options.Host == "" {
return nil, nil, errors.New("Empty host value")
}
var priv interface{}
switch options.EcdsaCurve {
case "":
if options.Ed25519Key {
_, priv, err = ed25519.GenerateKey(rand.Reader)
} else {
priv, err = rsa.GenerateKey(rand.Reader, options.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:
err = fmt.Errorf("Unrecognized elliptic curve: %q", options.EcdsaCurve)
return
}
if err != nil {
err = fmt.Errorf("Failed to generate private key: %v", err)
return
}
// ECDSA, ED25519 and RSA subject keys should have the DigitalSignature
// KeyUsage bits set in the x509.Certificate template
keyUsage := x509.KeyUsageDigitalSignature
// Only RSA subject keys should have the KeyEncipherment KeyUsage bits set. In
// the context of TLS this KeyUsage is particular to RSA key exchange and
// authentication.
if _, isRSA := priv.(*rsa.PrivateKey); isRSA {
keyUsage |= x509.KeyUsageKeyEncipherment
}
var notBefore time.Time
if len(options.ValidFrom) == 0 {
notBefore = time.Now()
} else {
notBefore, err = time.Parse("Jan 2 15:04:05 2006", options.ValidFrom)
if err != nil {
err = fmt.Errorf("Failed to parse creation date: %v", err)
return
}
}
notAfter := notBefore.Add(options.ValidFor)
serialNumberLimit := new(big.Int).Lsh(big.NewInt(1), 128)
serialNumber, err := rand.Int(rand.Reader, serialNumberLimit)
if err != nil {
err = fmt.Errorf("Failed to generate serial number: %v", err)
return
}
template := x509.Certificate{
SerialNumber: serialNumber,
Subject: pkix.Name{
Organization: []string{options.Organization},
},
NotBefore: notBefore,
NotAfter: notAfter,
KeyUsage: keyUsage,
ExtKeyUsage: []x509.ExtKeyUsage{x509.ExtKeyUsageServerAuth},
BasicConstraintsValid: true,
}
hosts := strings.Split(options.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 options.IsCA {
template.IsCA = true
template.KeyUsage |= x509.KeyUsageCertSign
}
derBytes, err := x509.CreateCertificate(rand.Reader, &template, &template, pubKey(priv), priv)
if err != nil {
err = fmt.Errorf("Failed to create certificate: %v", err)
return
}
var pubKeyBuf bytes.Buffer
pubKeyBufb := bufio.NewWriter(&pubKeyBuf)
err = pem.Encode(pubKeyBufb, &pem.Block{Type: "CERTIFICATE", Bytes: derBytes})
if err != nil {
err = fmt.Errorf("Failed to write data to cert.pem: %v", err)
return
}
pubKeyBufb.Flush()
privBytes, err := x509.MarshalPKCS8PrivateKey(priv)
if err != nil {
err = fmt.Errorf("Unable to marshal private key: %v", err)
return
}
var privKeyBuf bytes.Buffer
privKeyBufb := bufio.NewWriter(&privKeyBuf)
err = pem.Encode(privKeyBufb, &pem.Block{Type: "PRIVATE KEY", Bytes: privBytes})
if err != nil {
err = fmt.Errorf("Failed to write data to key.pem: %v", err)
return
}
privKeyBufb.Flush()
return pubKeyBuf.Bytes(), privKeyBuf.Bytes(), nil
}