Fix parsing issue of AEAD encrypted messages.

In pgpMessage.SeparateKeyAndData(), the parsing would
ignore AEAD encrypted data packets. Which would result
in a split message with a nil data packet.
We add support for AEAD encrypted data packets.
This also affects `NewPGPSplitMessageFromArmored` and `NewPGPSplitMessage`.

CHANGELOG.md

@@ -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

crypto/message.go

@@ -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
@@ -345,13 +344,38 @@ 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
+			outSplit.DataPacket, err = readPacketContents(p.Contents, estimatedLength, garbageCollector)
+			if err != nil {
+				return nil, err
+			}
+		case *packet.AEADEncrypted:
+			outSplit.DataPacket, err = readPacketContents(p.Contents, estimatedLength, garbageCollector)
+			if err != nil {
+				return nil, err
+			}
+		}
+	}
+	if encryptedKey == nil {
+		return nil, errors.New("gopenpgp: packets don't include an encrypted key packet")
+	}
+
+	var buf bytes.Buffer
+	if err := encryptedKey.Serialize(&buf); err != nil {
+		return nil, errors.Wrap(err, "gopenpgp: cannot serialize encrypted key")
+	}
+	outSplit.KeyPacket = buf.Bytes()
+
+	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.
@@ -370,7 +394,7 @@ func (msg *PGPMessage) SeparateKeyAndData(estimatedLength, garbageCollector int)
 	actualLength := 1
 	block := make([]byte, 128)
 	for {
-				n, err := p.Contents.Read(block)
+		n, err := contents.Read(block)
 		if goerrors.Is(err, io.EOF) {
 			break
 		}
@@ -406,20 +430,7 @@ func (msg *PGPMessage) SeparateKeyAndData(estimatedLength, garbageCollector int)
 		symEncryptedData[4] = byte(actualLength >> 8)
 		symEncryptedData[5] = byte(actualLength)
 	}
-			outSplit.DataPacket = symEncryptedData
+	return symEncryptedData, nil
-		}
-	}
-	if encryptedKey == nil {
-		return nil, errors.New("gopenpgp: packets don't include an encrypted key packet")
-	}
-
-	var buf bytes.Buffer
-	if err := encryptedKey.Serialize(&buf); err != nil {
-		return nil, errors.Wrap(err, "gopenpgp: cannot serialize encrypted key")
-	}
-	outSplit.KeyPacket = buf.Bytes()
-
-	return outSplit, nil
 }
 
 // GetBinary returns the unarmored binary content of the signature as a []byte.

crypto/message_test.go

@@ -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")
+	}
+}