PapaTutuWawa/omemo_dart
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feat: Calculate the Appended Data

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This commit is contained in:
PapaTutuWawa 2022-08-02 15:26:00 +02:00
parent 12e617ead9
commit fc43655956
2 changed files with 27 additions and 8 deletions
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30
lib/src/x3dh.dart
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@ -7,12 +7,13 @@ import 'package:omemo_dart/src/key.dart';
/// The overarching assumption is that we use Ed25519 keys for the identity keys /// The overarching assumption is that we use Ed25519 keys for the identity keys
/// Performed by Alice /// Performed by Alice
class X3DHResult { class X3DHAliceResult {
const X3DHResult(this.ek, this.sk, this.opkId); const X3DHAliceResult(this.ek, this.sk, this.opkId, this.ad);
final OmemoKeyPair ek; final OmemoKeyPair ek;
final List<int> sk; final List<int> sk;
final String opkId; final String opkId;
final List<int> ad;
} }
/// Received by Bob /// Received by Bob
@ -24,6 +25,13 @@ class X3DHMessage {
final String opkId; final String opkId;
} }
class X3DHBobResult {
const X3DHBobResult(this.sk, this.ad);
final List<int> sk;
final List<int> ad;
}
/// Sign [message] using the keypair [keyPair]. Note that [keyPair] must be /// Sign [message] using the keypair [keyPair]. Note that [keyPair] must be
/// a Ed25519 keypair. /// a Ed25519 keypair.
Future<List<int>> sig(OmemoKeyPair keyPair, List<int> message) async { Future<List<int>> sig(OmemoKeyPair keyPair, List<int> message) async {
@ -90,7 +98,7 @@ List<int> concat(List<List<int>> inputs) {
/// Alice builds a session with Bob using his bundle [bundle] and Alice's identity key /// Alice builds a session with Bob using his bundle [bundle] and Alice's identity key
/// pair [ik]. /// pair [ik].
Future<X3DHResult> x3dhFromBundle(OmemoBundle bundle, OmemoKeyPair ik) async { Future<X3DHAliceResult> x3dhFromBundle(OmemoBundle bundle, OmemoKeyPair ik) async {
// Generate EK // Generate EK
final ek = await OmemoKeyPair.generateNewPair(KeyPairType.x25519); final ek = await OmemoKeyPair.generateNewPair(KeyPairType.x25519);
@ -105,17 +113,27 @@ Future<X3DHResult> x3dhFromBundle(OmemoBundle bundle, OmemoKeyPair ik) async {
final dh4 = await dh(ek, opk, 0); final dh4 = await dh(ek, opk, 0);
final sk = await kdf(concat([dh1, dh2, dh3, dh4])); final sk = await kdf(concat([dh1, dh2, dh3, dh4]));
final ad = concat([
await ik.pk.getBytes(),
await bundle.ik.getBytes(),
]);
return X3DHResult(ek, sk, opkId); return X3DHAliceResult(ek, sk, opkId, ad);
} }
/// Bob builds the X3DH shared secret from the inital message [msg], the SPK [spk], the /// Bob builds the X3DH shared secret from the inital message [msg], the SPK [spk], the
/// OPK [opk] that was selected by Alice and our IK [ik]. Returns the shared secret. /// OPK [opk] that was selected by Alice and our IK [ik]. Returns the shared secret.
Future<List<int>> x3dhFromInitialMessage(X3DHMessage msg, OmemoKeyPair spk, OmemoKeyPair opk, OmemoKeyPair ik) async { Future<X3DHBobResult> x3dhFromInitialMessage(X3DHMessage msg, OmemoKeyPair spk, OmemoKeyPair opk, OmemoKeyPair ik) async {
final dh1 = await dh(spk, msg.ik, 2); final dh1 = await dh(spk, msg.ik, 2);
final dh2 = await dh(ik, msg.ek, 1); final dh2 = await dh(ik, msg.ek, 1);
final dh3 = await dh(spk, msg.ek, 0); final dh3 = await dh(spk, msg.ek, 0);
final dh4 = await dh(opk, msg.ek, 0); final dh4 = await dh(opk, msg.ek, 0);
return kdf(concat([dh1, dh2, dh3, dh4])); final sk = await kdf(concat([dh1, dh2, dh3, dh4]));
final ad = concat([
await msg.ik.getBytes(),
await ik.pk.getBytes(),
]);
return X3DHBobResult(sk, ad);
} }

5
test/x3dh_test.dart
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@ -28,7 +28,7 @@ void main() {
// ... // ...
// Bob does X3DH // Bob does X3DH
final skBob = await x3dhFromInitialMessage( final resultBob = await x3dhFromInitialMessage(
X3DHMessage( X3DHMessage(
ikAlice.pk, ikAlice.pk,
resultAlice.ek.pk, resultAlice.ek.pk,
@ -39,6 +39,7 @@ void main() {
ikBob, ikBob,
); );
expect(resultAlice.sk, skBob); expect(resultAlice.sk, resultBob.sk);
expect(resultAlice.ad, resultBob.ad);
}); });
} }