MXCrossSigning: Gossip the master key

fixes element-hq/element-ios/issues/3346
matrix-org · Jun 25, 2020 · a445438 · a445438
1 parent fa348c9
commit a445438
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Showing 4 changed files with 63 additions and 3 deletions.
diff --git a/CHANGES.rst b/CHANGES.rst
@@ -6,7 +6,9 @@ Improvements:
  * MXCrossSigning: Add the bootstrapWithAuthParams method.
  * MXRecoveryService: Create this service to manage keys we want to store in SSSS.
  * MXRecoveryService: Add deleteRecovery.
- * MXSecretStorage: Add options to remove secrets and SSSS. * MXWellKnown: Add JSONDictionary implementation to return original and extended data.
+ * MXSecretStorage: Add options to remove secrets and SSSS. 
+ * MXWellKnown: Add JSONDictionary implementation to return original and extended data.
+ * MXCrossSigning: Gossip the master key (vector-im/riot-ios/issues/3346).
 
 Bug fix:
  * MXSecretShareManager: Fix crash in cancelRequestWithRequestId (vector-im/riot-ios/issues/3272).

diff --git a/MatrixSDK/Crypto/CrossSigning/MXCrossSigning.h b/MatrixSDK/Crypto/CrossSigning/MXCrossSigning.h
@@ -94,6 +94,7 @@ typedef NS_ENUM(NSInteger, MXCrossSigningErrorCode)
 @property (nonatomic, readonly) MXCrossSigningState state;
 @property (nonatomic, readonly) BOOL canTrustCrossSigning;
 @property (nonatomic, readonly) BOOL canCrossSign;
+@property (nonatomic, readonly) BOOL hasAllPrivateKeys;
 
 /**
  Check update for this device cross-signing state (self.state).

diff --git a/MatrixSDK/Crypto/CrossSigning/MXCrossSigning.m b/MatrixSDK/Crypto/CrossSigning/MXCrossSigning.m
@@ -48,6 +48,15 @@ - (BOOL)canTrustCrossSigning
     return (_state >= MXCrossSigningStateTrustCrossSigning);
 }
 
+- (BOOL)hasAllPrivateKeys
+{
+    id<MXCryptoStore> cryptoStore = self.crypto.store;
+
+    return ([cryptoStore secretWithSecretId:MXSecretId.crossSigningMaster]
+            && [cryptoStore secretWithSecretId:MXSecretId.crossSigningSelfSigning]
+            && [cryptoStore secretWithSecretId:MXSecretId.crossSigningUserSigning]);
+}
+
 - (void)bootstrapWithPassword:(NSString*)password
                       success:(void (^)(void))success
                       failure:(void (^)(NSError *error))failure
@@ -75,6 +84,9 @@ - (void)bootstrapWithAuthParams:(NSDictionary*)authParams
 {
     MXCredentials *myCreds = _crypto.mxSession.matrixRestClient.credentials;
 
+
+    // TODO: Check if it exists before
+
     // Create keys
     NSDictionary<NSString*, NSData*> *privateKeys;
     MXCrossSigningInfo *keys = [self createKeys:&privateKeys];
@@ -282,12 +294,51 @@ - (void)requestPrivateKeysToDeviceIds:(nullable NSArray<NSString*>*)deviceIds
 {
     NSLog(@"[MXCrossSigning] requestPrivateKeysToDeviceIds: %@", deviceIds);
 
-    // Make a secret share request for USK and SSK
+    // Make a secret share request for MSK, USK and SSK
     dispatch_group_t successGroup = dispatch_group_create();
     dispatch_group_t onPrivateKeysReceivedGroup = dispatch_group_create();
 
-    __block NSString *uskRequestId, *sskRequestId;
+    __block NSString *mskRequestId, *uskRequestId, *sskRequestId;
+
+
+    // MSK
+    dispatch_group_enter(successGroup);
+    dispatch_group_enter(onPrivateKeysReceivedGroup);
+    [self.crypto.secretShareManager requestSecret:MXSecretId.crossSigningMaster toDeviceIds:deviceIds success:^(NSString * _Nonnull requestId) {
+        mskRequestId = requestId;
+        dispatch_group_leave(successGroup);
+    } onSecretReceived:^BOOL(NSString * _Nonnull secret) {
+
+        BOOL isSecretValid = NO;
+        if (self.myUserCrossSigningKeys.masterKeys.keys)
+        {
+            isSecretValid = [self isSecretValid:secret forPublicKeys:self.myUserCrossSigningKeys.masterKeys.keys];
+        }
+        else
+        {
+            // Accept the secret anyway (It should not happen)
+            isSecretValid = YES;
+        }
+
+        NSLog(@"[MXCrossSigning] requestPrivateKeysToDeviceIds: Got MSK. isSecretValid: %@", @(isSecretValid));
+        if (isSecretValid)
+        {
+            [self.crypto.store storeSecret:secret withSecretId:MXSecretId.crossSigningMaster];
+            dispatch_group_leave(onPrivateKeysReceivedGroup);
+        }
+        return isSecretValid;
+    } failure:^(NSError * _Nonnull error) {
+        // Cancel the other request
+        if (mskRequestId)
+        {
+            [self.crypto.secretShareManager cancelRequestWithRequestId:mskRequestId success:^{} failure:^(NSError * _Nonnull error) {
+            }];
+        }
+        failure(error);
+    }];
+
 
+    // USK
     dispatch_group_enter(successGroup);
     dispatch_group_enter(onPrivateKeysReceivedGroup);
     [self.crypto.secretShareManager requestSecret:MXSecretId.crossSigningUserSigning toDeviceIds:deviceIds success:^(NSString * _Nonnull requestId) {
@@ -323,6 +374,8 @@ - (void)requestPrivateKeysToDeviceIds:(nullable NSArray<NSString*>*)deviceIds
         failure(error);
     }];
 
+
+    // SSK
     dispatch_group_enter(successGroup);
     dispatch_group_enter(onPrivateKeysReceivedGroup);
     [self.crypto.secretShareManager requestSecret:MXSecretId.crossSigningSelfSigning toDeviceIds:deviceIds success:^(NSString * _Nonnull requestId) {

diff --git a/MatrixSDKTests/MXCrossSigningTests.m b/MatrixSDKTests/MXCrossSigningTests.m
@@ -470,6 +470,7 @@ - (void)testRefreshState
 //   This simulates a self verification and trigger cross-signing behind the shell
 // - The 2nd device requests cross-signing keys from the 1st one
 // -> The 2nd device should be able to cross-sign now
+// -> The 2nd device must have all cross-signing private keys
 - (void)testPrivateKeysGossiping
 {
     // - Create Alice
@@ -498,6 +499,9 @@ - (void)testPrivateKeysGossiping
 
                                     // -> The 2nd device should be able to cross-sign now
                                     XCTAssertEqual(newAliceSession.crypto.crossSigning.state, MXCrossSigningStateCanCrossSign);
+
+                                    // -> The 2nd device must have all cross-signing private keys
+                                    XCTAssertTrue(newAliceSession.crypto.crossSigning.hasAllPrivateKeys);
                                     [expectation fulfill];
 
                                 } failure:^(NSError * _Nonnull error) {