274149dd14
* Switch to keybase go-crypto (for some elliptic curve key) + test
* Use assert.NoError
and add a little more context to failing test description
* Use assert.(No)Error everywhere 🌈
and assert.Error in place of .Nil/.NotNil
227 lines
6.9 KiB
Go
227 lines
6.9 KiB
Go
// 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 (
|
|
"encoding/binary"
|
|
"io"
|
|
"math/big"
|
|
"strconv"
|
|
|
|
"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/rsa"
|
|
)
|
|
|
|
const encryptedKeyVersion = 3
|
|
|
|
// EncryptedKey represents a public-key encrypted session key. See RFC 4880,
|
|
// section 5.1.
|
|
type EncryptedKey struct {
|
|
KeyId uint64
|
|
Algo PublicKeyAlgorithm
|
|
CipherFunc CipherFunction // only valid after a successful Decrypt
|
|
Key []byte // only valid after a successful Decrypt
|
|
|
|
encryptedMPI1, encryptedMPI2 parsedMPI
|
|
ecdh_C []byte
|
|
}
|
|
|
|
func (e *EncryptedKey) parse(r io.Reader) (err error) {
|
|
var buf [10]byte
|
|
_, err = readFull(r, buf[:])
|
|
if err != nil {
|
|
return
|
|
}
|
|
if buf[0] != encryptedKeyVersion {
|
|
return errors.UnsupportedError("unknown EncryptedKey version " + strconv.Itoa(int(buf[0])))
|
|
}
|
|
e.KeyId = binary.BigEndian.Uint64(buf[1:9])
|
|
e.Algo = PublicKeyAlgorithm(buf[9])
|
|
switch e.Algo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
|
|
e.encryptedMPI1.bytes, e.encryptedMPI1.bitLength, err = readMPI(r)
|
|
case PubKeyAlgoElGamal:
|
|
e.encryptedMPI1.bytes, e.encryptedMPI1.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return
|
|
}
|
|
e.encryptedMPI2.bytes, e.encryptedMPI2.bitLength, err = readMPI(r)
|
|
case PubKeyAlgoECDH:
|
|
e.encryptedMPI1.bytes, e.encryptedMPI1.bitLength, err = readMPI(r)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
_, err = readFull(r, buf[:1]) // read C len (1 byte)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
e.ecdh_C = make([]byte, int(buf[0]))
|
|
_, err = readFull(r, e.ecdh_C)
|
|
}
|
|
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
_, err = consumeAll(r)
|
|
return err
|
|
}
|
|
|
|
func checksumKeyMaterial(key []byte) uint16 {
|
|
var checksum uint16
|
|
for _, v := range key {
|
|
checksum += uint16(v)
|
|
}
|
|
return checksum
|
|
}
|
|
|
|
// Decrypt decrypts an encrypted session key with the given private key. The
|
|
// private key must have been decrypted first.
|
|
// If config is nil, sensible defaults will be used.
|
|
func (e *EncryptedKey) Decrypt(priv *PrivateKey, config *Config) error {
|
|
var err error
|
|
var b []byte
|
|
|
|
// TODO(agl): use session key decryption routines here to avoid
|
|
// padding oracle attacks.
|
|
switch priv.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
|
|
b, err = rsa.DecryptPKCS1v15(config.Random(), priv.PrivateKey.(*rsa.PrivateKey), e.encryptedMPI1.bytes)
|
|
case PubKeyAlgoElGamal:
|
|
c1 := new(big.Int).SetBytes(e.encryptedMPI1.bytes)
|
|
c2 := new(big.Int).SetBytes(e.encryptedMPI2.bytes)
|
|
b, err = elgamal.Decrypt(priv.PrivateKey.(*elgamal.PrivateKey), c1, c2)
|
|
case PubKeyAlgoECDH:
|
|
// Note: Unmarshal checks if point is on the curve.
|
|
c1, c2 := ecdh.Unmarshal(priv.PrivateKey.(*ecdh.PrivateKey).Curve, e.encryptedMPI1.bytes)
|
|
if c1 == nil {
|
|
return errors.InvalidArgumentError("failed to parse EC point for encryption key")
|
|
}
|
|
b, err = decryptKeyECDH(priv, c1, c2, e.ecdh_C)
|
|
default:
|
|
err = errors.InvalidArgumentError("cannot decrypted encrypted session key with private key of type " + strconv.Itoa(int(priv.PubKeyAlgo)))
|
|
}
|
|
|
|
if err != nil {
|
|
return err
|
|
}
|
|
|
|
e.CipherFunc = CipherFunction(b[0])
|
|
e.Key = b[1 : len(b)-2]
|
|
expectedChecksum := uint16(b[len(b)-2])<<8 | uint16(b[len(b)-1])
|
|
checksum := checksumKeyMaterial(e.Key)
|
|
if checksum != expectedChecksum {
|
|
return errors.StructuralError("EncryptedKey checksum incorrect")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// Serialize writes the encrypted key packet, e, to w.
|
|
func (e *EncryptedKey) Serialize(w io.Writer) error {
|
|
var mpiLen int
|
|
switch e.Algo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
|
|
mpiLen = 2 + len(e.encryptedMPI1.bytes)
|
|
case PubKeyAlgoElGamal:
|
|
mpiLen = 2 + len(e.encryptedMPI1.bytes) + 2 + len(e.encryptedMPI2.bytes)
|
|
default:
|
|
return errors.InvalidArgumentError("don't know how to serialize encrypted key type " + strconv.Itoa(int(e.Algo)))
|
|
}
|
|
|
|
serializeHeader(w, packetTypeEncryptedKey, 1 /* version */ +8 /* key id */ +1 /* algo */ +mpiLen)
|
|
|
|
w.Write([]byte{encryptedKeyVersion})
|
|
binary.Write(w, binary.BigEndian, e.KeyId)
|
|
w.Write([]byte{byte(e.Algo)})
|
|
|
|
switch e.Algo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
|
|
writeMPIs(w, e.encryptedMPI1)
|
|
case PubKeyAlgoElGamal:
|
|
writeMPIs(w, e.encryptedMPI1, e.encryptedMPI2)
|
|
default:
|
|
panic("internal error")
|
|
}
|
|
|
|
return nil
|
|
}
|
|
|
|
// SerializeEncryptedKey serializes an encrypted key packet to w that contains
|
|
// key, encrypted to pub.
|
|
// If config is nil, sensible defaults will be used.
|
|
func SerializeEncryptedKey(w io.Writer, pub *PublicKey, cipherFunc CipherFunction, key []byte, config *Config) error {
|
|
var buf [10]byte
|
|
buf[0] = encryptedKeyVersion
|
|
binary.BigEndian.PutUint64(buf[1:9], pub.KeyId)
|
|
buf[9] = byte(pub.PubKeyAlgo)
|
|
|
|
keyBlock := make([]byte, 1 /* cipher type */ +len(key)+2 /* checksum */)
|
|
keyBlock[0] = byte(cipherFunc)
|
|
copy(keyBlock[1:], key)
|
|
checksum := checksumKeyMaterial(key)
|
|
keyBlock[1+len(key)] = byte(checksum >> 8)
|
|
keyBlock[1+len(key)+1] = byte(checksum)
|
|
|
|
switch pub.PubKeyAlgo {
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
|
|
return serializeEncryptedKeyRSA(w, config.Random(), buf, pub.PublicKey.(*rsa.PublicKey), keyBlock)
|
|
case PubKeyAlgoElGamal:
|
|
return serializeEncryptedKeyElGamal(w, config.Random(), buf, pub.PublicKey.(*elgamal.PublicKey), keyBlock)
|
|
case PubKeyAlgoECDH:
|
|
return serializeEncryptedKeyECDH(w, config.Random(), buf, pub, keyBlock)
|
|
case PubKeyAlgoDSA, PubKeyAlgoRSASignOnly:
|
|
return errors.InvalidArgumentError("cannot encrypt to public key of type " + strconv.Itoa(int(pub.PubKeyAlgo)))
|
|
}
|
|
|
|
return errors.UnsupportedError("encrypting a key to public key of type " + strconv.Itoa(int(pub.PubKeyAlgo)))
|
|
}
|
|
|
|
func serializeEncryptedKeyRSA(w io.Writer, rand io.Reader, header [10]byte, pub *rsa.PublicKey, keyBlock []byte) error {
|
|
cipherText, err := rsa.EncryptPKCS1v15(rand, pub, keyBlock)
|
|
if err != nil {
|
|
return errors.InvalidArgumentError("RSA encryption failed: " + err.Error())
|
|
}
|
|
|
|
packetLen := 10 /* header length */ + 2 /* mpi size */ + len(cipherText)
|
|
|
|
err = serializeHeader(w, packetTypeEncryptedKey, packetLen)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
_, err = w.Write(header[:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return writeMPI(w, 8*uint16(len(cipherText)), cipherText)
|
|
}
|
|
|
|
func serializeEncryptedKeyElGamal(w io.Writer, rand io.Reader, header [10]byte, pub *elgamal.PublicKey, keyBlock []byte) error {
|
|
c1, c2, err := elgamal.Encrypt(rand, pub, keyBlock)
|
|
if err != nil {
|
|
return errors.InvalidArgumentError("ElGamal encryption failed: " + err.Error())
|
|
}
|
|
|
|
packetLen := 10 /* header length */
|
|
packetLen += 2 /* mpi size */ + (c1.BitLen()+7)/8
|
|
packetLen += 2 /* mpi size */ + (c2.BitLen()+7)/8
|
|
|
|
err = serializeHeader(w, packetTypeEncryptedKey, packetLen)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
_, err = w.Write(header[:])
|
|
if err != nil {
|
|
return err
|
|
}
|
|
err = writeBig(w, c1)
|
|
if err != nil {
|
|
return err
|
|
}
|
|
return writeBig(w, c2)
|
|
}
|