forked from golang/crypto
/
private_key.go
564 lines (492 loc) · 13.9 KB
/
private_key.go
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// 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/cipher"
"crypto/dsa"
"crypto/ecdsa"
"crypto/sha1"
"fmt"
"io"
"io/ioutil"
"math/big"
"strconv"
"time"
"github.com/keybase/go-crypto/ed25519"
"github.com/keybase/go-crypto/openpgp/ecdh"
"github.com/keybase/go-crypto/openpgp/elgamal"
"github.com/keybase/go-crypto/openpgp/errors"
"github.com/keybase/go-crypto/openpgp/s2k"
"github.com/keybase/go-crypto/rsa"
)
// 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.PrivateKey or *dsa.PrivateKey.
sha1Checksum bool
iv []byte
s2kHeader []byte
}
type EdDSAPrivateKey struct {
PrivateKey
seed parsedMPI
}
func (e *EdDSAPrivateKey) Seed() []byte {
return e.seed.bytes
}
func (e *EdDSAPrivateKey) Sign(digest []byte) (R, S []byte, err error) {
r := bytes.NewReader(e.seed.bytes)
publicKey, privateKey, err := ed25519.GenerateKey(r)
if err != nil {
return nil, nil, err
}
if !bytes.Equal(publicKey, e.PublicKey.edk.p.bytes[1:]) { // [1:] because [0] is 0x40 mpi header
return nil, nil, errors.UnsupportedError("EdDSA: Private key does not match public key.")
}
sig := ed25519.Sign(privateKey, digest)
sigLen := ed25519.SignatureSize / 2
return sig[:sigLen], sig[sigLen:], nil
}
func NewRSAPrivateKey(currentTime time.Time, priv *rsa.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewRSAPublicKey(currentTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewDSAPrivateKey(currentTime time.Time, priv *dsa.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewDSAPublicKey(currentTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewElGamalPrivateKey(currentTime time.Time, priv *elgamal.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewElGamalPublicKey(currentTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewECDSAPrivateKey(currentTime time.Time, priv *ecdsa.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewECDSAPublicKey(currentTime, &priv.PublicKey)
pk.PrivateKey = priv
return pk
}
func NewECDHPrivateKey(currentTime time.Time, priv *ecdh.PrivateKey) *PrivateKey {
pk := new(PrivateKey)
pk.PublicKey = *NewECDHPublicKey(currentTime, &priv.PublicKey)
pk.PrivateKey = priv
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
}
// S2K == nil implies that we got a "GNU Dummy" S2K. For instance,
// because our master secret key is on a USB key in a vault somewhere.
// In that case, there is no further data to consume here.
if pk.s2k == nil {
pk.Encrypted = false
return
}
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
}
// Encrypt is the counterpart to the Decrypt() method below. It encrypts
// the private key with the provided passphrase. If config is nil, then
// the standard, and sensible, defaults apply.
//
// A key will be derived from the given passphrase using S2K Specifier
// Type 3 (Iterated + Salted, see RFC-4880 Sec. 3.7.1.3). This choice
// is hardcoded in s2k.Serialize(). S2KCount is hardcoded to 0, which is
// equivalent to 65536. And the hash algorithm for key-derivation can be
// set with config. The encrypted PrivateKey, using the algorithm specified
// in config (if provided), is written out to the encryptedData member.
// When Serialize() is called, this encryptedData member will be
// serialized, using S2K Usage value of 254, and thus SHA1 checksum.
func (pk *PrivateKey) Encrypt(passphrase []byte, config *Config) (err error) {
if pk.PrivateKey == nil {
return errors.InvalidArgumentError("there is no private key to encrypt")
}
pk.sha1Checksum = true
pk.cipher = config.Cipher()
s2kConfig := s2k.Config{
Hash: config.Hash(),
S2KCount: 0,
}
s2kBuf := bytes.NewBuffer(nil)
derivedKey := make([]byte, pk.cipher.KeySize())
err = s2k.Serialize(s2kBuf, derivedKey, config.Random(), passphrase, &s2kConfig)
if err != nil {
return err
}
pk.s2kHeader = s2kBuf.Bytes()
// No good way to set pk.s2k but to call s2k.Parse(),
// even though we have all the information here, but
// most of the functions needed are private to s2k.
pk.s2k, err = s2k.Parse(s2kBuf)
pk.iv = make([]byte, pk.cipher.blockSize())
if _, err = config.Random().Read(pk.iv); err != nil {
return err
}
privateKeyBuf := bytes.NewBuffer(nil)
if err = pk.serializePrivateKey(privateKeyBuf); err != nil {
return err
}
checksum := sha1.Sum(privateKeyBuf.Bytes())
if _, err = privateKeyBuf.Write(checksum[:]); err != nil {
return err
}
pkData := privateKeyBuf.Bytes()
block := pk.cipher.new(derivedKey)
pk.encryptedData = make([]byte, len(pkData))
cfb := cipher.NewCFBEncrypter(block, pk.iv)
cfb.XORKeyStream(pk.encryptedData, pkData)
pk.Encrypted = true
return nil
}
func (pk *PrivateKey) Serialize(w io.Writer) (err error) {
buf := bytes.NewBuffer(nil)
err = pk.PublicKey.serializeWithoutHeaders(buf)
if err != nil {
return
}
privateKeyBuf := bytes.NewBuffer(nil)
if pk.PrivateKey == nil {
_, err = buf.Write([]byte{
254, // SHA-1 Convention
9, // Encryption scheme (AES256)
101, // GNU Extensions
2, // Hash value (SHA1)
'G', 'N', 'U', // "GNU" as a string
1, // Extension type 1001 (minus 1000)
})
} else if pk.Encrypted {
_, err = buf.Write([]byte{
254, // SHA-1 Convention
byte(pk.cipher), // Encryption scheme
})
if err != nil {
return err
}
if _, err = buf.Write(pk.s2kHeader); err != nil {
return err
}
if _, err = buf.Write(pk.iv); err != nil {
return err
}
if _, err = privateKeyBuf.Write(pk.encryptedData); err != nil {
return err
}
} else {
buf.WriteByte(0 /* no encryption */)
if err = pk.serializePrivateKey(privateKeyBuf); err != nil {
return err
}
}
ptype := packetTypePrivateKey
contents := buf.Bytes()
privateKeyBytes := privateKeyBuf.Bytes()
if pk.IsSubkey {
ptype = packetTypePrivateSubkey
}
totalLen := len(contents) + len(privateKeyBytes)
if !pk.Encrypted {
totalLen += 2
}
err = serializeHeader(w, ptype, totalLen)
if err != nil {
return
}
_, err = w.Write(contents)
if err != nil {
return
}
_, err = w.Write(privateKeyBytes)
if err != nil {
return
}
if len(privateKeyBytes) > 0 && !pk.Encrypted {
checksum := mod64kHash(privateKeyBytes)
var checksumBytes [2]byte
checksumBytes[0] = byte(checksum >> 8)
checksumBytes[1] = byte(checksum)
_, err = w.Write(checksumBytes[:])
}
return
}
func (pk *PrivateKey) serializePrivateKey(w io.Writer) (err error) {
switch priv := pk.PrivateKey.(type) {
case *rsa.PrivateKey:
err = serializeRSAPrivateKey(w, priv)
case *dsa.PrivateKey:
err = serializeDSAPrivateKey(w, priv)
case *elgamal.PrivateKey:
err = serializeElGamalPrivateKey(w, priv)
case *ecdsa.PrivateKey:
err = serializeECDSAPrivateKey(w, priv)
case *ecdh.PrivateKey:
err = serializeECDHPrivateKey(w, priv)
case *EdDSAPrivateKey:
err = serializeEdDSAPrivateKey(w, priv)
default:
err = errors.InvalidArgumentError("unknown private key type")
}
return err
}
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)
}
func serializeECDHPrivateKey(w io.Writer, priv *ecdh.PrivateKey) error {
return writeBig(w, priv.X)
}
func serializeEdDSAPrivateKey(w io.Writer, priv *EdDSAPrivateKey) error {
return writeMPI(w, priv.seed.bitLength, priv.seed.bytes)
}
// Decrypt decrypts an encrypted private key using a passphrase.
func (pk *PrivateKey) Decrypt(passphrase []byte) error {
if !pk.Encrypted {
return nil
}
// For GNU Dummy S2K, there's no key here, so don't do anything.
if pk.s2k == nil {
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)
case PubKeyAlgoECDH:
return pk.parseECDHPrivateKey(data)
case PubKeyAlgoEdDSA:
return pk.parseEdDSAPrivateKey(data)
case PubKeyAlgoBadElGamal:
return errors.UnsupportedError("parsing el-gamal sign-or-encrypt privatekeys is unsupported")
default:
return errors.UnsupportedError("cannot parse this private key type")
}
}
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) parseECDHPrivateKey(data []byte) (err error) {
pub := pk.PublicKey.PublicKey.(*ecdh.PublicKey)
priv := new(ecdh.PrivateKey)
priv.PublicKey = *pub
buf := bytes.NewBuffer(data)
d, _, err := readMPI(buf)
if err != nil {
return
}
priv.X = new(big.Int).SetBytes(d)
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)
ecdsaPriv := new(ecdsa.PrivateKey)
ecdsaPriv.PublicKey = *ecdsaPub
buf := bytes.NewBuffer(data)
d, _, err := readMPI(buf)
if err != nil {
return
}
ecdsaPriv.D = new(big.Int).SetBytes(d)
pk.PrivateKey = ecdsaPriv
pk.Encrypted = false
pk.encryptedData = nil
return nil
}
func (pk *PrivateKey) parseEdDSAPrivateKey(data []byte) (err error) {
eddsaPriv := new(EdDSAPrivateKey)
eddsaPriv.PublicKey = pk.PublicKey
buf := bytes.NewBuffer(data)
eddsaPriv.seed.bytes, eddsaPriv.seed.bitLength, err = readMPI(buf)
if err != nil {
return err
}
if bLen := len(eddsaPriv.seed.bytes); bLen != 32 { // 32 bytes private part of ed25519 key.
return errors.UnsupportedError(fmt.Sprintf("Unexpected EdDSA private key length: %d", bLen))
}
pk.PrivateKey = eddsaPriv
pk.Encrypted = false
pk.encryptedData = nil
return nil
}