mirror of
https://github.com/rocky-linux/peridot.git
synced 2024-10-19 15:55:08 +00:00
268 lines
7.9 KiB
Go
268 lines
7.9 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 (
|
||
|
"bytes"
|
||
|
"crypto/cipher"
|
||
|
"io"
|
||
|
"strconv"
|
||
|
|
||
|
"github.com/ProtonMail/go-crypto/openpgp/errors"
|
||
|
"github.com/ProtonMail/go-crypto/openpgp/s2k"
|
||
|
)
|
||
|
|
||
|
// This is the largest session key that we'll support. Since no 512-bit cipher
|
||
|
// has even been seriously used, this is comfortably large.
|
||
|
const maxSessionKeySizeInBytes = 64
|
||
|
|
||
|
// SymmetricKeyEncrypted represents a passphrase protected session key. See RFC
|
||
|
// 4880, section 5.3.
|
||
|
type SymmetricKeyEncrypted struct {
|
||
|
Version int
|
||
|
CipherFunc CipherFunction
|
||
|
Mode AEADMode
|
||
|
s2k func(out, in []byte)
|
||
|
aeadNonce []byte
|
||
|
encryptedKey []byte
|
||
|
}
|
||
|
|
||
|
func (ske *SymmetricKeyEncrypted) parse(r io.Reader) error {
|
||
|
// RFC 4880, section 5.3.
|
||
|
var buf [2]byte
|
||
|
if _, err := readFull(r, buf[:]); err != nil {
|
||
|
return err
|
||
|
}
|
||
|
ske.Version = int(buf[0])
|
||
|
if ske.Version != 4 && ske.Version != 5 {
|
||
|
return errors.UnsupportedError("unknown SymmetricKeyEncrypted version")
|
||
|
}
|
||
|
ske.CipherFunc = CipherFunction(buf[1])
|
||
|
if ske.CipherFunc.KeySize() == 0 {
|
||
|
return errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(buf[1])))
|
||
|
}
|
||
|
|
||
|
if ske.Version == 5 {
|
||
|
mode := make([]byte, 1)
|
||
|
if _, err := r.Read(mode); err != nil {
|
||
|
return errors.StructuralError("cannot read AEAD octect from packet")
|
||
|
}
|
||
|
ske.Mode = AEADMode(mode[0])
|
||
|
}
|
||
|
|
||
|
var err error
|
||
|
if ske.s2k, err = s2k.Parse(r); err != nil {
|
||
|
if _, ok := err.(errors.ErrDummyPrivateKey); ok {
|
||
|
return errors.UnsupportedError("missing key GNU extension in session key")
|
||
|
}
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
if ske.Version == 5 {
|
||
|
// AEAD nonce
|
||
|
nonce := make([]byte, ske.Mode.NonceLength())
|
||
|
_, err := readFull(r, nonce)
|
||
|
if err != nil && err != io.ErrUnexpectedEOF {
|
||
|
return err
|
||
|
}
|
||
|
ske.aeadNonce = nonce
|
||
|
}
|
||
|
|
||
|
encryptedKey := make([]byte, maxSessionKeySizeInBytes)
|
||
|
// The session key may follow. We just have to try and read to find
|
||
|
// out. If it exists then we limit it to maxSessionKeySizeInBytes.
|
||
|
n, err := readFull(r, encryptedKey)
|
||
|
if err != nil && err != io.ErrUnexpectedEOF {
|
||
|
return err
|
||
|
}
|
||
|
|
||
|
if n != 0 {
|
||
|
if n == maxSessionKeySizeInBytes {
|
||
|
return errors.UnsupportedError("oversized encrypted session key")
|
||
|
}
|
||
|
ske.encryptedKey = encryptedKey[:n]
|
||
|
}
|
||
|
return nil
|
||
|
}
|
||
|
|
||
|
// Decrypt attempts to decrypt an encrypted session key and returns the key and
|
||
|
// the cipher to use when decrypting a subsequent Symmetrically Encrypted Data
|
||
|
// packet.
|
||
|
func (ske *SymmetricKeyEncrypted) Decrypt(passphrase []byte) ([]byte, CipherFunction, error) {
|
||
|
key := make([]byte, ske.CipherFunc.KeySize())
|
||
|
ske.s2k(key, passphrase)
|
||
|
if len(ske.encryptedKey) == 0 {
|
||
|
return key, ske.CipherFunc, nil
|
||
|
}
|
||
|
switch ske.Version {
|
||
|
case 4:
|
||
|
plaintextKey, cipherFunc, err := ske.decryptV4(key)
|
||
|
return plaintextKey, cipherFunc, err
|
||
|
case 5:
|
||
|
plaintextKey, err := ske.decryptV5(key)
|
||
|
return plaintextKey, CipherFunction(0), err
|
||
|
}
|
||
|
err := errors.UnsupportedError("unknown SymmetricKeyEncrypted version")
|
||
|
return nil, CipherFunction(0), err
|
||
|
}
|
||
|
|
||
|
func (ske *SymmetricKeyEncrypted) decryptV4(key []byte) ([]byte, CipherFunction, error) {
|
||
|
// the IV is all zeros
|
||
|
iv := make([]byte, ske.CipherFunc.blockSize())
|
||
|
c := cipher.NewCFBDecrypter(ske.CipherFunc.new(key), iv)
|
||
|
plaintextKey := make([]byte, len(ske.encryptedKey))
|
||
|
c.XORKeyStream(plaintextKey, ske.encryptedKey)
|
||
|
cipherFunc := CipherFunction(plaintextKey[0])
|
||
|
if cipherFunc.blockSize() == 0 {
|
||
|
return nil, ske.CipherFunc, errors.UnsupportedError(
|
||
|
"unknown cipher: " + strconv.Itoa(int(cipherFunc)))
|
||
|
}
|
||
|
plaintextKey = plaintextKey[1:]
|
||
|
if len(plaintextKey) != cipherFunc.KeySize() {
|
||
|
return nil, cipherFunc, errors.StructuralError(
|
||
|
"length of decrypted key not equal to cipher keysize")
|
||
|
}
|
||
|
return plaintextKey, cipherFunc, nil
|
||
|
}
|
||
|
|
||
|
func (ske *SymmetricKeyEncrypted) decryptV5(key []byte) ([]byte, error) {
|
||
|
blockCipher := CipherFunction(ske.CipherFunc).new(key)
|
||
|
aead := ske.Mode.new(blockCipher)
|
||
|
|
||
|
adata := []byte{0xc3, byte(5), byte(ske.CipherFunc), byte(ske.Mode)}
|
||
|
plaintextKey, err := aead.Open(nil, ske.aeadNonce, ske.encryptedKey, adata)
|
||
|
if err != nil {
|
||
|
return nil, err
|
||
|
}
|
||
|
return plaintextKey, nil
|
||
|
}
|
||
|
|
||
|
// SerializeSymmetricKeyEncrypted serializes a symmetric key packet to w.
|
||
|
// The packet contains a random session key, encrypted by a key derived from
|
||
|
// the given passphrase. The session key is returned and must be passed to
|
||
|
// SerializeSymmetricallyEncrypted or SerializeAEADEncrypted, depending on
|
||
|
// whether config.AEADConfig != nil.
|
||
|
// If config is nil, sensible defaults will be used.
|
||
|
func SerializeSymmetricKeyEncrypted(w io.Writer, passphrase []byte, config *Config) (key []byte, err error) {
|
||
|
cipherFunc := config.Cipher()
|
||
|
keySize := cipherFunc.KeySize()
|
||
|
if keySize == 0 {
|
||
|
return nil, errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(cipherFunc)))
|
||
|
}
|
||
|
|
||
|
sessionKey := make([]byte, keySize)
|
||
|
_, err = io.ReadFull(config.Random(), sessionKey)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
|
||
|
err = SerializeSymmetricKeyEncryptedReuseKey(w, sessionKey, passphrase, config)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
|
||
|
key = sessionKey
|
||
|
return
|
||
|
}
|
||
|
|
||
|
// SerializeSymmetricKeyEncryptedReuseKey serializes a symmetric key packet to w.
|
||
|
// The packet contains the given session key, encrypted by a key derived from
|
||
|
// the given passphrase. The session key must be passed to
|
||
|
// SerializeSymmetricallyEncrypted or SerializeAEADEncrypted, depending on
|
||
|
// whether config.AEADConfig != nil.
|
||
|
// If config is nil, sensible defaults will be used.
|
||
|
func SerializeSymmetricKeyEncryptedReuseKey(w io.Writer, sessionKey []byte, passphrase []byte, config *Config) (err error) {
|
||
|
var version int
|
||
|
if config.AEAD() != nil {
|
||
|
version = 5
|
||
|
} else {
|
||
|
version = 4
|
||
|
}
|
||
|
cipherFunc := config.Cipher()
|
||
|
keySize := cipherFunc.KeySize()
|
||
|
if keySize == 0 {
|
||
|
return errors.UnsupportedError("unknown cipher: " + strconv.Itoa(int(cipherFunc)))
|
||
|
}
|
||
|
|
||
|
s2kBuf := new(bytes.Buffer)
|
||
|
keyEncryptingKey := make([]byte, keySize)
|
||
|
// s2k.Serialize salts and stretches the passphrase, and writes the
|
||
|
// resulting key to keyEncryptingKey and the s2k descriptor to s2kBuf.
|
||
|
err = s2k.Serialize(s2kBuf, keyEncryptingKey, config.Random(), passphrase, &s2k.Config{Hash: config.Hash(), S2KCount: config.PasswordHashIterations()})
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
s2kBytes := s2kBuf.Bytes()
|
||
|
|
||
|
var packetLength int
|
||
|
switch version {
|
||
|
case 4:
|
||
|
packetLength = 2 /* header */ + len(s2kBytes) + 1 /* cipher type */ + keySize
|
||
|
case 5:
|
||
|
nonceLen := config.AEAD().Mode().NonceLength()
|
||
|
tagLen := config.AEAD().Mode().TagLength()
|
||
|
packetLength = 3 + len(s2kBytes) + nonceLen + keySize + tagLen
|
||
|
}
|
||
|
err = serializeHeader(w, packetTypeSymmetricKeyEncrypted, packetLength)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
|
||
|
buf := make([]byte, 2)
|
||
|
// Symmetric Key Encrypted Version
|
||
|
buf[0] = byte(version)
|
||
|
// Cipher function
|
||
|
buf[1] = byte(cipherFunc)
|
||
|
|
||
|
if version == 5 {
|
||
|
// AEAD mode
|
||
|
buf = append(buf, byte(config.AEAD().Mode()))
|
||
|
}
|
||
|
_, err = w.Write(buf)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
_, err = w.Write(s2kBytes)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
|
||
|
switch version {
|
||
|
case 4:
|
||
|
iv := make([]byte, cipherFunc.blockSize())
|
||
|
c := cipher.NewCFBEncrypter(cipherFunc.new(keyEncryptingKey), iv)
|
||
|
encryptedCipherAndKey := make([]byte, keySize+1)
|
||
|
c.XORKeyStream(encryptedCipherAndKey, buf[1:])
|
||
|
c.XORKeyStream(encryptedCipherAndKey[1:], sessionKey)
|
||
|
_, err = w.Write(encryptedCipherAndKey)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
case 5:
|
||
|
blockCipher := cipherFunc.new(keyEncryptingKey)
|
||
|
mode := config.AEAD().Mode()
|
||
|
aead := mode.new(blockCipher)
|
||
|
// Sample nonce using random reader
|
||
|
nonce := make([]byte, config.AEAD().Mode().NonceLength())
|
||
|
_, err = io.ReadFull(config.Random(), nonce)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
// Seal and write (encryptedData includes auth. tag)
|
||
|
adata := []byte{0xc3, byte(5), byte(cipherFunc), byte(mode)}
|
||
|
encryptedData := aead.Seal(nil, nonce, sessionKey, adata)
|
||
|
_, err = w.Write(nonce)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
_, err = w.Write(encryptedData)
|
||
|
if err != nil {
|
||
|
return
|
||
|
}
|
||
|
}
|
||
|
|
||
|
return
|
||
|
}
|