Analytics | Report expected UTDs as HistoricalMessage error

Author: BillCarsonFr

Riot/Modules/Analytics/DecryptionFailure+Analytics.swift

@@ -21,23 +21,34 @@ extension DecryptionFailure {
 
     public func toAnalyticsEvent() -> AnalyticsEvent.Error {
 
-        let timeToDecryptMillis: Int = if self.timeToDecrypt != nil {
-            Int(self.timeToDecrypt! * 1000)
+        let timeToDecryptMillis: Int = if let ttd = self.timeToDecrypt {
+            Int(ttd * 1000)
         } else {
             -1
         }
+        
+        let isHistoricalEvent = if let localAge = self.eventLocalAgeMillis {
+            localAge < 0
+        } else { false }
+        
+        let errorName = if isHistoricalEvent && self.trustOwnIdentityAtTimeOfFailure == false {
+            AnalyticsEvent.Error.Name.HistoricalMessage
+        } else {
+            self.reason.errorName
+        }
+        
         return AnalyticsEvent.Error(
             context: self.context,
             cryptoModule: .Rust,
             cryptoSDK: .Rust,
             domain: .E2EE,
 
-            eventLocalAgeMillis: nil,
+            eventLocalAgeMillis: self.eventLocalAgeMillis,
             isFederated: nil,
             isMatrixDotOrg: nil,
-            name: self.reason.errorName,
+            name: errorName,
             timeToDecryptMillis: timeToDecryptMillis,
-            userTrustsOwnIdentity: nil,
+            userTrustsOwnIdentity: self.trustOwnIdentityAtTimeOfFailure,
             wasVisibleToUser: nil
         )
     }

Riot/Modules/Analytics/DecryptionFailure.swift

@@ -47,6 +47,11 @@ import AnalyticsEvents
     /// UTDs can be permanent or temporary. If temporary, this field will contain the time it took to decrypt the message in milliseconds. If permanent should be nil
     var timeToDecrypt: TimeInterval?
 
+    /// Was the current cross-signing identity trusted at the time of decryption
+    var trustOwnIdentityAtTimeOfFailure: Bool?
+    
+    var eventLocalAgeMillis: Int?
+    
     init(failedEventId: String, reason: DecryptionFailureReason, context: String, ts: TimeInterval) {
         self.failedEventId = failedEventId
         self.reason = reason

Riot/Modules/Analytics/DecryptionFailureTracker.swift

@@ -62,14 +62,14 @@ class DecryptionFailureTracker: NSObject {
                                                selector: #selector(eventDidDecrypt(_:)),
                                                name: .mxEventDidDecrypt,
                                                object: nil)
-        
     }
 
     @objc
-    func reportUnableToDecryptError(forEvent event: MXEvent, withRoomState roomState: MXRoomState, myUser userId: String) {
+    func reportUnableToDecryptError(forEvent event: MXEvent, withRoomState roomState: MXRoomState, mySession: MXSession) {
         if reportedFailures[event.eventId] != nil || trackedEvents.contains(event.eventId) {
             return
         }
+        guard let userId = mySession.myUserId else { return }
 
         // Filter out "expected" UTDs
         // We cannot decrypt messages sent before the user joined the room
@@ -82,6 +82,12 @@ class DecryptionFailureTracker: NSObject {
 
         guard let error = event.decryptionError as? NSError else { return }
 
+        let eventOrigin = event.originServerTs
+        let deviceTimestamp = mySession.crypto.deviceCreationTs
+        // If negative it's an historical event relative to the current session
+        let eventRelativeAgeMillis = Int(eventOrigin) - Int(deviceTimestamp)
+        let isSessionVerified = mySession.crypto.crossSigning.canTrustCrossSigning
+        
         var reason = DecryptionFailureReason.unspecified
 
         if error.code == MXDecryptingErrorUnknownInboundSessionIdCode.rawValue {
@@ -92,7 +98,13 @@ class DecryptionFailureTracker: NSObject {
 
         let context = String(format: "code: %ld, description: %@", error.code, event.decryptionError.localizedDescription)
 
-        reportedFailures[failedEventId] = DecryptionFailure(failedEventId: failedEventId, reason: reason, context: context, ts: self.timeProvider.nowTs())
+        let failure = DecryptionFailure(failedEventId: failedEventId, reason: reason, context: context, ts: self.timeProvider.nowTs())
+        
+        failure.eventLocalAgeMillis = Int(exactly: eventRelativeAgeMillis)
+        failure.trustOwnIdentityAtTimeOfFailure = isSessionVerified
+        
+        reportedFailures[failedEventId] = failure
+        
 
         // Start the ticker if needed. There is no need to have a ticker if no failures are tracked
         if checkFailuresTimer == nil {

Riot/Utils/EventFormatter.m

@@ -334,7 +334,7 @@ - (NSAttributedString *)unsafeAttributedStringFromEvent:(MXEvent *)event
     {
         // Track e2e failures
         dispatch_async(dispatch_get_main_queue(), ^{
-            [[DecryptionFailureTracker sharedInstance] reportUnableToDecryptErrorForEvent:event withRoomState:roomState myUser:self->mxSession.myUser.userId];
+            [[DecryptionFailureTracker sharedInstance] reportUnableToDecryptErrorForEvent:event withRoomState:roomState mySession:self->mxSession];
         });
 
         if (event.decryptionError.code == MXDecryptingErrorUnknownInboundSessionIdCode)