Merge pull request #187 from ProtonMail/feat/session_key_aead_decryption

Add support for decrypting AEAD data packets with a session key.

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
+
+### Added
+- `SessionKey.Decrypt() and SessionKey.DecryptAndVerify`, now suport the decryption of AEAD encrypted 
+data packets (packet type 20).
+
 ## [2.4.7] 2022-04-27
 
 ### Changed

crypto/keyring_message_test.go

@@ -0,0 +1,38 @@
+package crypto
+
+import (
+	"io/ioutil"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestAEADKeyRingDecryption(t *testing.T) {
+	pgpMessageData, err := ioutil.ReadFile("testdata/gpg2.3-aead-pgp-message.pgp")
+	if err != nil {
+		t.Fatal("Expected no error when reading message data, got:", err)
+	}
+	pgpMessage := NewPGPMessage(pgpMessageData)
+
+	aeadKey, err := NewKeyFromArmored(readTestFile("gpg2.3-aead-test-key.asc", false))
+	if err != nil {
+		t.Fatal("Expected no error when unarmoring key, got:", err)
+	}
+
+	aeadKeyUnlocked, err := aeadKey.Unlock([]byte("test"))
+	if err != nil {
+		t.Fatal("Expected no error when unlocking, got:", err)
+	}
+	kR, err := NewKeyRing(aeadKeyUnlocked)
+	if err != nil {
+		t.Fatal("Expected no error when creating the keyring, got:", err)
+	}
+	defer kR.ClearPrivateParams()
+
+	decrypted, err := kR.Decrypt(pgpMessage, nil, 0)
+	if err != nil {
+		t.Fatal("Expected no error when decrypting, got:", err)
+	}
+
+	assert.Exactly(t, "hello world\n", decrypted.GetString())
+}

crypto/sessionkey.go

@@ -327,17 +327,19 @@ func decryptStreamWithSessionKey(sk *SessionKey, messageReader io.Reader, verify
 
 	// Decrypt data packet
 	switch p := p.(type) {
-	case *packet.SymmetricallyEncrypted:
+	case *packet.SymmetricallyEncrypted, *packet.AEADEncrypted:
 		dc, err := sk.GetCipherFunc()
 		if err != nil {
 			return nil, errors.Wrap(err, "gopenpgp: unable to decrypt with session key")
 		}
-
-		decrypted, err = p.Decrypt(dc, sk.Key)
+		encryptedDataPacket, isDataPacket := p.(packet.EncryptedDataPacket)
+		if !isDataPacket {
+			return nil, errors.Wrap(err, "gopenpgp: unknown data packet")
+		}
+		decrypted, err = encryptedDataPacket.Decrypt(dc, sk.Key)
 		if err != nil {
 			return nil, errors.Wrap(err, "gopenpgp: unable to decrypt symmetric packet")
 		}
-
 	default:
 		return nil, errors.New("gopenpgp: invalid packet type")
 	}

crypto/sessionkey_test.go

@@ -4,6 +4,7 @@ import (
 	"encoding/base64"
 	"encoding/hex"
 	"errors"
+	"io/ioutil"
 	"testing"
 
 	"github.com/ProtonMail/gopenpgp/v2/constants"
@@ -344,3 +345,42 @@ func TestAsymmetricKeyPacketDecryptionFailure(t *testing.T) {
 	_, err = ukr.DecryptSessionKey(keyPacket)
 	assert.Error(t, err, "gopenpgp: unable to decrypt session key")
 }
+
+func TestAEADDataPacketDecryption(t *testing.T) {
+	pgpMessageData, err := ioutil.ReadFile("testdata/gpg2.3-aead-pgp-message.pgp")
+	if err != nil {
+		t.Fatal("Expected no error when reading message data, got:", err)
+	}
+	pgpMessage := NewPGPMessage(pgpMessageData)
+
+	split, err := pgpMessage.SplitMessage()
+	if err != nil {
+		t.Fatal("Expected no error when splitting, got:", err)
+	}
+
+	aeadKey, err := NewKeyFromArmored(readTestFile("gpg2.3-aead-test-key.asc", false))
+	if err != nil {
+		t.Fatal("Expected no error when unarmoring key, got:", err)
+	}
+
+	aeadKeyUnlocked, err := aeadKey.Unlock([]byte("test"))
+	if err != nil {
+		t.Fatal("Expected no error when unlocking, got:", err)
+	}
+	kR, err := NewKeyRing(aeadKeyUnlocked)
+	if err != nil {
+		t.Fatal("Expected no error when creating the keyring, got:", err)
+	}
+	defer kR.ClearPrivateParams()
+	sessionKey, err := kR.DecryptSessionKey(split.GetBinaryKeyPacket())
+	if err != nil {
+		t.Fatal("Expected no error when decrypting session key, got:", err)
+	}
+
+	decrypted, err := sessionKey.Decrypt(split.GetBinaryDataPacket())
+	if err != nil {
+		t.Fatal("Expected no error when decrypting, got:", err)
+	}
+
+	assert.Exactly(t, "hello world\n", decrypted.GetString())
+}

crypto/testdata/gpg2.3-aead-pgp-message.pgp

@@ -0,0 +1 @@
+„^Y7p²}‹•
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crypto/testdata/gpg2.3-aead-test-key.asc

@@ -0,0 +1,17 @@
+-----BEGIN PGP PRIVATE KEY BLOCK-----
+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+=pBZD
+-----END PGP PRIVATE KEY BLOCK-----