Refactor encryption trust level

2026-04-26 03:20:50 +02:00 · 2023-03-13 16:18:11 +00:00
parent ef95ef4ab4
commit e3a32e1c5f
14 changed files with 286 additions and 59 deletions
@@ -0,0 +1,68 @@
+// 
+// Copyright 2023 New Vector Ltd
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+//
+
+import Foundation
+
+/// Object responsible for calculating user and room trust level
+///
+/// For legacy reasons, the trust of multiple items is represented as `Progress` object,
+/// where `completedUnitCount` represents the number of trusted users / devices.
+@objc class EncryptionTrustLevel: NSObject {
+    struct TrustSummary {
+        let totalCount: Int64
+        let trustedCount: Int64
+        let areAllTrusted: Bool
+        
+        init(progress: Progress) {
+            totalCount = max(progress.totalUnitCount, progress.completedUnitCount)
+            trustedCount = progress.completedUnitCount
+            areAllTrusted = trustedCount == totalCount
+        }
+    }
+    
+    
+    /// Calculate trust level for a single user given their cross-signing info
+    @objc func userTrustLevel(
+        crossSigning: MXCrossSigningInfo?,
+        trustedDevicesProgress: Progress
+    ) -> UserEncryptionTrustLevel {
+        let devices = TrustSummary(progress: trustedDevicesProgress)
+        
+        // If we could cross-sign but we haven't, the user is simply not verified
+        if let crossSigning, !crossSigning.trustLevel.isVerified {
+            return .notVerified
+        
+        // If we cannot cross-sign the user (legacy behaviour) and have not signed
+        // any devices manually, the user is not verified
+        } else if crossSigning == nil && devices.trustedCount == 0 {
+            return .notVerified
+        }
+        
+        // In all other cases we check devices for trust level
+        return devices.areAllTrusted ? .trusted : .warning
+    }
+    
+    /// Calculate trust level for a room given trust level of users and their devices
+    @objc func roomTrustLevel(summary: MXUsersTrustLevelSummary) -> RoomEncryptionTrustLevel {
+        let users = TrustSummary(progress: summary.trustedUsersProgress)
+        let devices = TrustSummary(progress: summary.trustedDevicesProgress)
+        
+        guard users.totalCount > 0 && users.areAllTrusted else {
+            return .normal
+        }
+        return devices.areAllTrusted ? .trusted : .warning
+    }
+}