// Copyright 2011 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.
package packet
import (
"bytes"
"crypto"
"crypto/cipher"
"crypto/dsa"
"crypto/ecdsa"
"crypto/rsa"
"crypto/sha1"
"io"
"io/ioutil"
"math/big"
"strconv"
"time"
"golang.org/x/crypto/openpgp/elgamal"
"golang.org/x/crypto/openpgp/errors"
"golang.org/x/crypto/openpgp/s2k"
)
// PrivateKey represents a possibly encrypted private key. See RFC 4880,
// section 5.5.3.
type PrivateKey struct {
PublicKey
Encrypted bool // if true then the private key is unavailable until Decrypt has been called.
encryptedData []byte
cipher CipherFunction
s2k func(out, in []byte)
PrivateKey interface{} // An *{rsa|dsa|ecdsa}.PrivateKey or a crypto.Signer.
sha1Checksum bool
iv []byte
}
func NewRSAPrivateKey(creationTime time.Time, priv *rsa.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewRSAPublicKey(creationTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewDSAPrivateKey(creationTime time.Time, priv *dsa.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewDSAPublicKey(creationTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewElGamalPrivateKey(creationTime time.Time, priv *elgamal.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewElGamalPublicKey(creationTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewECDSAPrivateKey(creationTime time.Time, priv *ecdsa.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewECDSAPublicKey(creationTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
// NewSignerPrivateKey creates a PrivateKey from a crypto.Signer that
// implements RSA or ECDSA.
func NewSignerPrivateKey(creationTime time.Time, signer crypto.Signer) *PrivateKey {
pk := new(PrivateKey)
// In general, the public Keys should be used as pointers. We still
// type-switch on the values, for backwards-compatibility.
switch pubkey := signer.Public().(type) {
case *rsa.PublicKey:
pk.PublicKey = *NewRSAPublicKey(creationTime, pubkey)
case rsa.PublicKey:
pk.PublicKey = *NewRSAPublicKey(creationTime, &pubkey)
case *ecdsa.PublicKey:
pk.PublicKey = *NewECDSAPublicKey(creationTime, pubkey)
case ecdsa.PublicKey:
pk.PublicKey = *NewECDSAPublicKey(creationTime, &pubkey)
default:
panic("openpgp: unknown crypto.Signer type in NewSignerPrivateKey")
}
pk.PrivateKey = signer
return pk
}
func (pk *PrivateKey) parse(r io.Reader) (err error) {
err = (&pk.PublicKey).parse(r)
if err != nil {
return
}
var buf [1]byte
_, err = readFull(r, buf[:])
if err != nil {
return
}
s2kType := buf[0]
switch s2kType {
case 0:
pk.s2k = nil
pk.Encrypted = false
case 254, 255:
_, err = readFull(r, buf[:])
if err != nil {
return
}
pk.cipher = CipherFunction(buf[0])
pk.Encrypted = true
pk.s2k, err = s2k.Parse(r)
if err != nil {
return
}
if s2kType == 254 {
pk.sha1Checksum = true
}
default:
return errors.UnsupportedError("deprecated s2k function in private key")
}
if pk.Encrypted {
blockSize := pk.cipher.blockSize()
if blockSize == 0 {
return errors.UnsupportedError("unsupported cipher in private key: " + strconv.Itoa(int(pk.cipher)))
}
pk.iv = make([]byte, blockSize)
_, err = readFull(r, pk.iv)
if err != nil {
return
}
}
pk.encryptedData, err = ioutil.ReadAll(r)
if err != nil {
return
}
if !pk.Encrypted {
return pk.parsePrivateKey(pk.encryptedData)
}
return
}
func mod64kHash(d []byte) uint16 {
var h uint16
for _, b := range d {
h += uint16(b)
}
return h
}
func (pk *PrivateKey) Serialize(w io.Writer) (err error) {
// TODO(agl): support encrypted private keys
buf := bytes.NewBuffer(nil)
err = pk.PublicKey.serializeWithoutHeaders(buf)
if err != nil {
return
}
buf.WriteByte(0 /* no encryption */)
privateKeyBuf := bytes.NewBuffer(nil)
switch priv := pk.PrivateKey.(type) {
case *rsa.PrivateKey:
err = serializeRSAPrivateKey(privateKeyBuf, priv)
case *dsa.PrivateKey:
err = serializeDSAPrivateKey(privateKeyBuf, priv)
case *elgamal.PrivateKey:
err = serializeElGamalPrivateKey(privateKeyBuf, priv)
case *ecdsa.PrivateKey:
err = serializeECDSAPrivateKey(privateKeyBuf, priv)
default:
err = errors.InvalidArgumentError("unknown private key type")
}
if err != nil {
return
}
ptype := packetTypePrivateKey
contents := buf.Bytes()
privateKeyBytes := privateKeyBuf.Bytes()
if pk.IsSubkey {
ptype = packetTypePrivateSubkey
}
err = serializeHeader(w, ptype, len(contents)+len(privateKeyBytes)+2)
if err != nil {
return
}
_, err = w.Write(contents)
if err != nil {
return
}
_, err = w.Write(privateKeyBytes)
if err != nil {
return
}
checksum := mod64kHash(privateKeyBytes)
var checksumBytes [2]byte
checksumBytes[0] = byte(checksum >> 8)
checksumBytes[1] = byte(checksum)
_, err = w.Write(checksumBytes[:])
return
}
func serializeRSAPrivateKey(w io.Writer, priv *rsa.PrivateKey) error {
err := writeBig(w, priv.D)
if err != nil {
return err
}
err = writeBig(w, priv.Primes[1])
if err != nil {
return err
}
err = writeBig(w, priv.Primes[0])
if err != nil {
return err
}
return writeBig(w, priv.Precomputed.Qinv)
}
func serializeDSAPrivateKey(w io.Writer, priv *dsa.PrivateKey) error {
return writeBig(w, priv.X)
}
func serializeElGamalPrivateKey(w io.Writer, priv *elgamal.PrivateKey) error {
return writeBig(w, priv.X)
}
func serializeECDSAPrivateKey(w io.Writer, priv *ecdsa.PrivateKey) error {
return writeBig(w, priv.D)
}
// Decrypt decrypts an encrypted private key using a passphrase.
func (pk *PrivateKey) Decrypt(passphrase []byte) error {
if !pk.Encrypted {
return nil
}
key := make([]byte, pk.cipher.KeySize())
pk.s2k(key, passphrase)
block := pk.cipher.new(key)
cfb := cipher.NewCFBDecrypter(block, pk.iv)
data := make([]byte, len(pk.encryptedData))
cfb.XORKeyStream(data, pk.encryptedData)
if pk.sha1Checksum {
if len(data) < sha1.Size {
return errors.StructuralError("truncated private key data")
}
h := sha1.New()
h.Write(data[:len(data)-sha1.Size])
sum := h.Sum(nil)
if !bytes.Equal(sum, data[len(data)-sha1.Size:]) {
return errors.StructuralError("private key checksum failure")
}
data = data[:len(data)-sha1.Size]
} else {
if len(data) < 2 {
return errors.StructuralError("truncated private key data")
}
var sum uint16
for i := 0; i < len(data)-2; i++ {
sum += uint16(data[i])
}
if data[len(data)-2] != uint8(sum>>8) ||
data[len(data)-1] != uint8(sum) {
return errors.StructuralError("private key checksum failure")
}
data = data[:len(data)-2]
}
return pk.parsePrivateKey(data)
}
func (pk *PrivateKey) parsePrivateKey(data []byte) (err error) {
switch pk.PublicKey.PubKeyAlgo {
case PubKeyAlgoRSA, PubKeyAlgoRSASignOnly, PubKeyAlgoRSAEncryptOnly:
return pk.parseRSAPrivateKey(data)
case PubKeyAlgoDSA:
return pk.parseDSAPrivateKey(data)
case PubKeyAlgoElGamal:
return pk.parseElGamalPrivateKey(data)
case PubKeyAlgoECDSA:
return pk.parseECDSAPrivateKey(data)
}
panic("impossible")
}
func (pk *PrivateKey) parseRSAPrivateKey(data []byte) (err error) {
rsaPub := pk.PublicKey.PublicKey.(*rsa.PublicKey)
rsaPriv := new(rsa.PrivateKey)
rsaPriv.PublicKey = *rsaPub
buf := bytes.NewBuffer(data)
d, _, err := readMPI(buf)
if err != nil {
return
}
p, _, err := readMPI(buf)
if err != nil {
return
}
q, _, err := readMPI(buf)
if err != nil {
return
}
rsaPriv.D = new(big.Int).SetBytes(d)
rsaPriv.Primes = make([]*big.Int, 2)
rsaPriv.Primes[0] = new(big.Int).SetBytes(p)
rsaPriv.Primes[1] = new(big.Int).SetBytes(q)
if err := rsaPriv.Validate(); err != nil {
return err
}
rsaPriv.Precompute()
pk.PrivateKey = rsaPriv
pk.Encrypted = false
pk.encryptedData = nil
return nil
}
func (pk *PrivateKey) parseDSAPrivateKey(data []byte) (err error) {
dsaPub := pk.PublicKey.PublicKey.(*dsa.PublicKey)
dsaPriv := new(dsa.PrivateKey)
dsaPriv.PublicKey = *dsaPub
buf := bytes.NewBuffer(data)
x, _, err := readMPI(buf)
if err != nil {
return
}
dsaPriv.X = new(big.Int).SetBytes(x)
pk.PrivateKey = dsaPriv
pk.Encrypted = false
pk.encryptedData = nil
return nil
}
func (pk *PrivateKey) parseElGamalPrivateKey(data []byte) (err error) {
pub := pk.PublicKey.PublicKey.(*elgamal.PublicKey)
priv := new(elgamal.PrivateKey)
priv.PublicKey = *pub
buf := bytes.NewBuffer(data)
x, _, err := readMPI(buf)
if err != nil {
return
}
priv.X = new(big.Int).SetBytes(x)
pk.PrivateKey = priv
pk.Encrypted = false
pk.encryptedData = nil
return nil
}
func (pk *PrivateKey) parseECDSAPrivateKey(data []byte) (err error) {
ecdsaPub := pk.PublicKey.PublicKey.(*ecdsa.PublicKey)
buf := bytes.NewBuffer(data)
d, _, err := readMPI(buf)
if err != nil {
return
}
pk.PrivateKey = &ecdsa.PrivateKey{
PublicKey: *ecdsaPub,
D: new(big.Int).SetBytes(d),
}
pk.Encrypted = false
pk.encryptedData = nil
return nil
}
