mirror of
https://github.com/cheat/cheat.git
synced 2024-11-30 01:36:53 +01:00
283 lines
8.8 KiB
Go
283 lines
8.8 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 (
|
||
|
|
"crypto"
|
||
|
|
"crypto/rsa"
|
||
|
|
"encoding/binary"
|
||
|
|
"io"
|
||
|
|
"math/big"
|
||
|
|
"strconv"
|
||
|
|
|
||
|
|
"github.com/ProtonMail/go-crypto/openpgp/ecdh"
|
||
|
|
"github.com/ProtonMail/go-crypto/openpgp/elgamal"
|
||
|
|
"github.com/ProtonMail/go-crypto/openpgp/errors"
|
||
|
|
"github.com/ProtonMail/go-crypto/openpgp/internal/encoding"
|
||
|
|
)
|
||
|
|
|
||
|
|
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 encoding.Field
|
||
|
|
}
|
||
|
|
|
||
|
|
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 = new(encoding.MPI)
|
||
|
|
if _, err = e.encryptedMPI1.ReadFrom(r); err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
case PubKeyAlgoElGamal:
|
||
|
|
e.encryptedMPI1 = new(encoding.MPI)
|
||
|
|
if _, err = e.encryptedMPI1.ReadFrom(r); err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
e.encryptedMPI2 = new(encoding.MPI)
|
||
|
|
if _, err = e.encryptedMPI2.ReadFrom(r); err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
case PubKeyAlgoECDH:
|
||
|
|
e.encryptedMPI1 = new(encoding.MPI)
|
||
|
|
if _, err = e.encryptedMPI1.ReadFrom(r); err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
e.encryptedMPI2 = new(encoding.OID)
|
||
|
|
if _, err = e.encryptedMPI2.ReadFrom(r); err != nil {
|
||
|
|
return
|
||
|
|
}
|
||
|
|
}
|
||
|
|
_, err = consumeAll(r)
|
||
|
|
return
|
||
|
|
}
|
||
|
|
|
||
|
|
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 {
|
||
|
|
if e.KeyId != 0 && e.KeyId != priv.KeyId {
|
||
|
|
return errors.InvalidArgumentError("cannot decrypt encrypted session key for key id " + strconv.FormatUint(e.KeyId, 16) + " with private key id " + strconv.FormatUint(priv.KeyId, 16))
|
||
|
|
}
|
||
|
|
if e.Algo != priv.PubKeyAlgo {
|
||
|
|
return errors.InvalidArgumentError("cannot decrypt encrypted session key of type " + strconv.Itoa(int(e.Algo)) + " with private key of type " + strconv.Itoa(int(priv.PubKeyAlgo)))
|
||
|
|
}
|
||
|
|
if priv.Dummy() {
|
||
|
|
return errors.ErrDummyPrivateKey("dummy key found")
|
||
|
|
}
|
||
|
|
|
||
|
|
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:
|
||
|
|
// Supports both *rsa.PrivateKey and crypto.Decrypter
|
||
|
|
k := priv.PrivateKey.(crypto.Decrypter)
|
||
|
|
b, err = k.Decrypt(config.Random(), padToKeySize(k.Public().(*rsa.PublicKey), e.encryptedMPI1.Bytes()), nil)
|
||
|
|
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:
|
||
|
|
vsG := e.encryptedMPI1.Bytes()
|
||
|
|
m := e.encryptedMPI2.Bytes()
|
||
|
|
oid := priv.PublicKey.oid.EncodedBytes()
|
||
|
|
b, err = ecdh.Decrypt(priv.PrivateKey.(*ecdh.PrivateKey), vsG, m, oid, priv.PublicKey.Fingerprint[:])
|
||
|
|
default:
|
||
|
|
err = errors.InvalidArgumentError("cannot decrypt 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 = int(e.encryptedMPI1.EncodedLength())
|
||
|
|
case PubKeyAlgoElGamal:
|
||
|
|
mpiLen = int(e.encryptedMPI1.EncodedLength()) + int(e.encryptedMPI2.EncodedLength())
|
||
|
|
case PubKeyAlgoECDH:
|
||
|
|
mpiLen = int(e.encryptedMPI1.EncodedLength()) + int(e.encryptedMPI2.EncodedLength())
|
||
|
|
default:
|
||
|
|
return errors.InvalidArgumentError("don't know how to serialize encrypted key type " + strconv.Itoa(int(e.Algo)))
|
||
|
|
}
|
||
|
|
|
||
|
|
err := serializeHeader(w, packetTypeEncryptedKey, 1 /* version */ +8 /* key id */ +1 /* algo */ +mpiLen)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
w.Write([]byte{encryptedKeyVersion})
|
||
|
|
binary.Write(w, binary.BigEndian, e.KeyId)
|
||
|
|
w.Write([]byte{byte(e.Algo)})
|
||
|
|
|
||
|
|
switch e.Algo {
|
||
|
|
case PubKeyAlgoRSA, PubKeyAlgoRSAEncryptOnly:
|
||
|
|
_, err := w.Write(e.encryptedMPI1.EncodedBytes())
|
||
|
|
return err
|
||
|
|
case PubKeyAlgoElGamal:
|
||
|
|
if _, err := w.Write(e.encryptedMPI1.EncodedBytes()); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
_, err := w.Write(e.encryptedMPI2.EncodedBytes())
|
||
|
|
return err
|
||
|
|
case PubKeyAlgoECDH:
|
||
|
|
if _, err := w.Write(e.encryptedMPI1.EncodedBytes()); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
_, err := w.Write(e.encryptedMPI2.EncodedBytes())
|
||
|
|
return err
|
||
|
|
default:
|
||
|
|
panic("internal error")
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// 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.PublicKey.(*ecdh.PublicKey), keyBlock, pub.oid, pub.Fingerprint)
|
||
|
|
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())
|
||
|
|
}
|
||
|
|
|
||
|
|
cipherMPI := encoding.NewMPI(cipherText)
|
||
|
|
packetLen := 10 /* header length */ + int(cipherMPI.EncodedLength())
|
||
|
|
|
||
|
|
err = serializeHeader(w, packetTypeEncryptedKey, packetLen)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
_, err = w.Write(header[:])
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
_, err = w.Write(cipherMPI.EncodedBytes())
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
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
|
||
|
|
}
|
||
|
|
if _, err = w.Write(new(encoding.MPI).SetBig(c1).EncodedBytes()); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
_, err = w.Write(new(encoding.MPI).SetBig(c2).EncodedBytes())
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
func serializeEncryptedKeyECDH(w io.Writer, rand io.Reader, header [10]byte, pub *ecdh.PublicKey, keyBlock []byte, oid encoding.Field, fingerprint []byte) error {
|
||
|
|
vsG, c, err := ecdh.Encrypt(rand, pub, keyBlock, oid.EncodedBytes(), fingerprint)
|
||
|
|
if err != nil {
|
||
|
|
return errors.InvalidArgumentError("ECDH encryption failed: " + err.Error())
|
||
|
|
}
|
||
|
|
|
||
|
|
g := encoding.NewMPI(vsG)
|
||
|
|
m := encoding.NewOID(c)
|
||
|
|
|
||
|
|
packetLen := 10 /* header length */
|
||
|
|
packetLen += int(g.EncodedLength()) + int(m.EncodedLength())
|
||
|
|
|
||
|
|
err = serializeHeader(w, packetTypeEncryptedKey, packetLen)
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
|
||
|
|
_, err = w.Write(header[:])
|
||
|
|
if err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
if _, err = w.Write(g.EncodedBytes()); err != nil {
|
||
|
|
return err
|
||
|
|
}
|
||
|
|
_, err = w.Write(m.EncodedBytes())
|
||
|
|
return err
|
||
|
|
}
|