From 1a0f470adac9e8b9a032674554ed5d9124ffd4ef Mon Sep 17 00:00:00 2001
From: "Alexander \"PapaTutuWawa" <papatutuwawa@polynom.me>
Date: Wed, 3 Aug 2022 15:29:13 +0200
Subject: [PATCH] feat: IMPLEMENT THE DOUBLE RATCHET WITH X3DH

---
 lib/src/double_ratchet.dart   | 13 ++++++-------
 test/double_ratchet_test.dart | 29 ++++++++++++++++++++++-------
 2 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/lib/src/double_ratchet.dart b/lib/src/double_ratchet.dart
index 04cf144..8a0c3e3 100644
--- a/lib/src/double_ratchet.dart
+++ b/lib/src/double_ratchet.dart
@@ -113,9 +113,9 @@ class OmemoDoubleRatchet {
 
     cks = newCks;
     final header = OMEMOMessage()
-      ..n = ns
+      ..dhPub = await dhs.pk.getBytes()
       ..pn = pn
-      ..dhPub = await dhs.pk.getBytes();
+      ..n = ns;
 
     ns++;
 
@@ -127,8 +127,7 @@ class OmemoDoubleRatchet {
 
   Future<List<int>?> trySkippedMessageKeys(OMEMOMessage header, List<int> ciphertext) async {
     final key = SkippedKey(
-      // TODO(PapaTutuWawa): Is this correct
-      OmemoPublicKey.fromBytes(header.dhPub, KeyPairType.ed25519),
+      OmemoPublicKey.fromBytes(header.dhPub, KeyPairType.x25519),
       header.n,
     );
     if (mkSkipped.containsKey(key)) {
@@ -162,13 +161,13 @@ class OmemoDoubleRatchet {
     pn = header.n;
     ns = 0;
     nr = 0;
-    dhr = OmemoPublicKey.fromBytes(header.dhPub, KeyPairType.ed25519);
+    dhr = OmemoPublicKey.fromBytes(header.dhPub, KeyPairType.x25519);
 
-    final newRk = await kdfRk(rk, await dh(dhs, dhr!, 2));
+    final newRk = await kdfRk(rk, await dh(dhs, dhr!, 0));
     rk = newRk;
     ckr = newRk;
     dhs = await OmemoKeyPair.generateNewPair(KeyPairType.x25519);
-    final newNewRk = await kdfRk(rk, await dh(dhs, dhr!, 2));
+    final newNewRk = await kdfRk(rk, await dh(dhs, dhr!, 0));
     rk = newNewRk;
     cks = newNewRk;
   }
diff --git a/test/double_ratchet_test.dart b/test/double_ratchet_test.dart
index ac464eb..5c527ee 100644
--- a/test/double_ratchet_test.dart
+++ b/test/double_ratchet_test.dart
@@ -1,3 +1,4 @@
+// ignore_for_file: avoid_print
 import 'dart:convert';
 import 'package:cryptography/cryptography.dart';
 import 'package:omemo_dart/omemo_dart.dart';
@@ -33,7 +34,6 @@ void main() {
     expect(decrypted, plaintext);
   });
 
-  /*
   test('Test the Double Ratchet', () async {
     // Generate keys
     final ikAlice = await OmemoKeyPair.generateNewPair(KeyPairType.ed25519);
@@ -90,20 +90,35 @@ void main() {
     //expect(await alicesRatchet.dhr.getBytes(), await ikBob.pk.getBytes());
     
     // Alice encrypts a message
-    final aliceRatchetResult = await alicesRatchet.ratchetEncrypt(utf8.encode('Hello Bob'));
+    final aliceRatchetResult1 = await alicesRatchet.ratchetEncrypt(utf8.encode('Hello Bob'));
     print('Alice sent the message');
 
     // Alice sends it to Bob
     // ...
 
     // Bob tries to decrypt it
-    final bobRatchetResult = await bobsRatchet.ratchetDecrypt(
-      aliceRatchetResult.header,
-      aliceRatchetResult.ciphertext,
+    final bobRatchetResult1 = await bobsRatchet.ratchetDecrypt(
+      aliceRatchetResult1.header,
+      aliceRatchetResult1.ciphertext,
     );
     print('Bob decrypted the message');
 
-    expect(utf8.encode('Hello Bob'), bobRatchetResult);
+    expect(utf8.encode('Hello Bob'), bobRatchetResult1);
+
+    // Bob sends a message to Alice
+    final bobRatchetResult2 = await bobsRatchet.ratchetEncrypt(utf8.encode('Hello Alice'));
+    print('Bob sent the message');
+
+    // Bobs sends it to Alice
+    // ...
+
+    // Alice tries to decrypt it
+    final aliceRatchetResult2 = await alicesRatchet.ratchetDecrypt(
+      bobRatchetResult2.header,
+      bobRatchetResult2.ciphertext,
+    );
+    print('Alice decrypted the message');
+
+    expect(utf8.encode('Hello Alice'), aliceRatchetResult2);
   });
-  */
 }