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Merge pull request #160 from ProtonMail/fix/split-message-aead

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Add support for AEADMessages in PGPMessage.SeparateKeyAndData
This commit is contained in:
wussler 2022-01-10 14:55:06 +01:00 • committed by GitHub
commit 14f558a276
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GPG key ID: 4AEE18F83AFDEB23
3 changed files with 96 additions and 56 deletions
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6
CHANGELOG.md
View file

@ -4,6 +4,12 @@ All notable changes to this project will be documented in this file.
The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
## Unreleased
### Fixed
- Fixed bug with `NewPGPSplitMessageFromArmored(armored)` and `PGPMessage.SeparateKeyAndData()`.
Those functions didn't parse AEAD encrypted messages correctly (eg messages encrypted with the latest versions of gnupg), resulting in a nil `DataPacket`.
## [2.4.0] 2021-12-21
### Added

123
crypto/message.go
View file

@ -333,7 +333,6 @@ func (msg *PGPMessage) SeparateKeyAndData(estimatedLength, garbageCollector int)
// For info on each, see: https://golang.org/pkg/runtime/#MemStats
packets := packet.NewReader(bytes.NewReader(msg.Data))
outSplit = &PGPSplitMessage{}
gcCounter := 0
// Store encrypted key and symmetrically encrypted packet separately
var encryptedKey *packet.EncryptedKey
@ -345,68 +344,21 @@ func (msg *PGPMessage) SeparateKeyAndData(estimatedLength, garbageCollector int)
}
switch p := p.(type) {
case *packet.EncryptedKey:
// TODO: add support for multiple keypackets
if encryptedKey != nil && encryptedKey.Key != nil {
break
}
encryptedKey = p
case *packet.SymmetricallyEncrypted:
// TODO: add support for multiple keypackets
var b bytes.Buffer
// 2^16 is an estimation of the size difference between input and output, the size difference is most probably
// 16 bytes at a maximum though.
// We need to avoid triggering a grow from the system as this will allocate too much memory causing problems
// in low-memory environments
b.Grow(1<<16 + estimatedLength)
// empty encoded length + start byte
if _, err := b.Write(make([]byte, 6)); err != nil {
return nil, errors.Wrap(err, "gopenpgp: error in writing data packet header")
outSplit.DataPacket, err = readPacketContents(p.Contents, estimatedLength, garbageCollector)
if err != nil {
return nil, err
}
if err := b.WriteByte(byte(1)); err != nil {
return nil, errors.Wrap(err, "gopenpgp: error in writing data packet header")
case *packet.AEADEncrypted:
outSplit.DataPacket, err = readPacketContents(p.Contents, estimatedLength, garbageCollector)
if err != nil {
return nil, err
}
actualLength := 1
block := make([]byte, 128)
for {
n, err := p.Contents.Read(block)
if goerrors.Is(err, io.EOF) {
break
}
if _, err := b.Write(block[:n]); err != nil {
return nil, errors.Wrap(err, "gopenpgp: error in writing data packet body")
}
actualLength += n
gcCounter += n
if gcCounter > garbageCollector && garbageCollector > 0 {
runtime.GC()
gcCounter = 0
}
}
// quick encoding
symEncryptedData := b.Bytes()
switch {
case actualLength < 192:
symEncryptedData[4] = byte(210)
symEncryptedData[5] = byte(actualLength)
symEncryptedData = symEncryptedData[4:]
case actualLength < 8384:
actualLength -= 192
symEncryptedData[3] = byte(210)
symEncryptedData[4] = 192 + byte(actualLength>>8)
symEncryptedData[5] = byte(actualLength)
symEncryptedData = symEncryptedData[3:]
default:
symEncryptedData[0] = byte(210)
symEncryptedData[1] = byte(255)
symEncryptedData[2] = byte(actualLength >> 24)
symEncryptedData[3] = byte(actualLength >> 16)
symEncryptedData[4] = byte(actualLength >> 8)
symEncryptedData[5] = byte(actualLength)
}
outSplit.DataPacket = symEncryptedData
}
}
if encryptedKey == nil {
@ -422,6 +374,65 @@ func (msg *PGPMessage) SeparateKeyAndData(estimatedLength, garbageCollector int)
return outSplit, nil
}
func readPacketContents(contents io.Reader, estimatedLength int, garbageCollector int) ([]byte, error) {
gcCounter := 0
var b bytes.Buffer
// 2^16 is an estimation of the size difference between input and output, the size difference is most probably
// 16 bytes at a maximum though.
// We need to avoid triggering a grow from the system as this will allocate too much memory causing problems
// in low-memory environments
b.Grow(1<<16 + estimatedLength)
// empty encoded length + start byte
if _, err := b.Write(make([]byte, 6)); err != nil {
return nil, errors.Wrap(err, "gopenpgp: error in writing data packet header")
}
if err := b.WriteByte(byte(1)); err != nil {
return nil, errors.Wrap(err, "gopenpgp: error in writing data packet header")
}
actualLength := 1
block := make([]byte, 128)
for {
n, err := contents.Read(block)
if goerrors.Is(err, io.EOF) {
break
}
if _, err := b.Write(block[:n]); err != nil {
return nil, errors.Wrap(err, "gopenpgp: error in writing data packet body")
}
actualLength += n
gcCounter += n
if gcCounter > garbageCollector && garbageCollector > 0 {
runtime.GC()
gcCounter = 0
}
}
// quick encoding
symEncryptedData := b.Bytes()
switch {
case actualLength < 192:
symEncryptedData[4] = byte(210)
symEncryptedData[5] = byte(actualLength)
symEncryptedData = symEncryptedData[4:]
case actualLength < 8384:
actualLength -= 192
symEncryptedData[3] = byte(210)
symEncryptedData[4] = 192 + byte(actualLength>>8)
symEncryptedData[5] = byte(actualLength)
symEncryptedData = symEncryptedData[3:]
default:
symEncryptedData[0] = byte(210)
symEncryptedData[1] = byte(255)
symEncryptedData[2] = byte(actualLength >> 24)
symEncryptedData[3] = byte(actualLength >> 16)
symEncryptedData[4] = byte(actualLength >> 8)
symEncryptedData[5] = byte(actualLength)
}
return symEncryptedData, nil
}
// GetBinary returns the unarmored binary content of the signature as a []byte.
func (sig *PGPSignature) GetBinary() []byte {
return sig.Data

23
crypto/message_test.go
View file

@ -439,3 +439,26 @@ func TestMessageGetArmoredWithEmptyHeaders(t *testing.T) {
assert.NotContains(t, armored, "Version")
assert.NotContains(t, armored, "Comment")
}
func TestPGPSplitMessageFromArmoredWithAEAD(t *testing.T) {
var message = `-----BEGIN PGP MESSAGE-----
hF4DJDxTg/yg6TkSAQdA3Ogzuxwz7IdSRCh81gdYuB0bKqkYDs7EksOkYJ7eUnMw
FsRNg+X3KbCj9j747An4J7V8trghOIN00dlpuR77wELS79XHoP55qmyVyPzmTXdx
1F8BCQIQyGCAxAA1ppydoBVp7ithTEl2bU72tbOsLCFY8TBamG6t3jfqJpO2lz+G
M0xNgvwIDrAQsN35VGw72I/FvWJ0VG3rpBKgFp5nPK0NblRomXTRRfoNgSoVUcxU
vA==
=YNf2
-----END PGP MESSAGE-----
`
split, err := NewPGPSplitMessageFromArmored(message)
if err != nil {
t.Errorf("Couldn't parse split message: %v", err)
}
if split.KeyPacket == nil {
t.Error("Key packet was nil")
}
if split.DataPacket == nil {
t.Error("Data packet was nil")
}
}