Display a badge for messages decrypted using shared keys. (#4937)

* feat: Show info badge for messages decrypted with shared keys

* tests: Add snapshots and tests for forwarder icon.

* fix: Update `EventBasedTimelineItemProtocol.hasStatusIcon`

* fix: Address review comments.

* fix: Use two translations for key forwarded dialog content.

* refactor: Rename `TimelineItemForwarder` to `TimelineItemKeyForwarder`.

Additionally adds a `[weak self]` guard to `encryptionForwarder` alert
handler.

* tests: Add `previewLayout` directive to `encryptionForwarder` previews

* refactor: Remove unused translations, use short-circuiting condition.

ElementX.xcodeproj/project.pbxproj

@@ -270,6 +270,7 @@
 		2D2D8A53B35BE8D8A01449C6 /* PinnedEventsBannerStateTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = 6FA38E813BE14149F173F461 /* PinnedEventsBannerStateTests.swift */; };
 		2D38D39B1789B91AE69F477F /* PhotoLibraryManagerMock.swift in Sources */ = {isa = PBXBuildFile; fileRef = DD955A0380C287C418F1A74D /* PhotoLibraryManagerMock.swift */; };
 		2D45A04699BB6BA3B3A0CB9A /* TracingHook.swift in Sources */ = {isa = PBXBuildFile; fileRef = 2A95C9B8299A36A6495DECA6 /* TracingHook.swift */; };
+		2D76463CE5A9238B5BB5F393 /* TimelineItemKeyForwarder.swift in Sources */ = {isa = PBXBuildFile; fileRef = DB6F137B69DCB59353E37B80 /* TimelineItemKeyForwarder.swift */; };
 		2DA27D78560D5F79B917E163 /* AudioConverter.swift in Sources */ = {isa = PBXBuildFile; fileRef = E44E35AA87F49503E7B3BF6E /* AudioConverter.swift */; };
 		2DD9D0FE7CB5CFC80D071451 /* AppLockScreenModels.swift in Sources */ = {isa = PBXBuildFile; fileRef = 3C3E67E09FE5A35D73818C39 /* AppLockScreenModels.swift */; };
 		2E43A3D221BE9587BC19C3F1 /* MatrixEntityRegexTests.swift in Sources */ = {isa = PBXBuildFile; fileRef = F31F59030205A6F65B057E1A /* MatrixEntityRegexTests.swift */; };
@@ -2734,6 +2735,7 @@
 		DADECBBB672497BCD4822468 /* Result.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Result.swift; sourceTree = "<group>"; };
 		DB06F22CFA34885B40976061 /* RoomDetailsEditScreen.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RoomDetailsEditScreen.swift; sourceTree = "<group>"; };
 		DB08D1F7C27A8C24EF81073C /* MapURLs.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MapURLs.swift; sourceTree = "<group>"; };
+		DB6F137B69DCB59353E37B80 /* TimelineItemKeyForwarder.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = TimelineItemKeyForwarder.swift; sourceTree = "<group>"; };
 		DBEDCEC9D908C19C63D24395 /* Info.plist */ = {isa = PBXFileReference; lastKnownFileType = text.plist; path = Info.plist; sourceTree = "<group>"; };
 		DC0AEA686E425F86F6BA0404 /* UNNotification+Creator.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UNNotification+Creator.swift"; sourceTree = "<group>"; };
 		DC10CCC8D68B863E20660DBC /* MessageForwardingScreenViewModelProtocol.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = MessageForwardingScreenViewModelProtocol.swift; sourceTree = "<group>"; };
@@ -4615,6 +4617,7 @@
 				314F1C79850BE46E8ABEAFCB /* ReadReceipt.swift */,
 				5DE8D25D6A91030175D52A20 /* RoomTimelineItemProperties.swift */,
 				2F926D08EB3D622A480BCA71 /* TimelineEventContent.swift */,
+				DB6F137B69DCB59353E37B80 /* TimelineItemKeyForwarder.swift */,
 				BE89A8BD65CCE3FCC925CA14 /* TimelineItemReplyDetails.swift */,
 				98C6A082F2B2A15E1B9BE280 /* TimelineItemThreadSummary.swift */,
 			);
@@ -8674,6 +8677,7 @@
 				79959F8E45C3749997482A7F /* TimelineItemBubbledStylerView.swift in Sources */,
 				A808DC3F72D15C6C5A52317E /* TimelineItemDebugView.swift in Sources */,
 				877D3CE8680536DB430DE6A2 /* TimelineItemIdentifier.swift in Sources */,
+				2D76463CE5A9238B5BB5F393 /* TimelineItemKeyForwarder.swift in Sources */,
 				C0B97FFEC0083F3A36609E61 /* TimelineItemMacContextMenu.swift in Sources */,
 				6C98153D60FF9B648C166C27 /* TimelineItemMenu.swift in Sources */,
 				AE07F215EBC2B9CBF17AA54B /* TimelineItemMenuAction.swift in Sources */,

ElementX/Sources/Screens/Timeline/TimelineModels.swift

@@ -138,6 +138,8 @@ struct TimelineViewState: BindableState {
     var linkMetadataProvider: LinkMetadataProviderProtocol?
     
     var mapTilerConfiguration: MapTilerConfiguration
+
+    var enableKeyShareOnInvite: Bool
     
     var bindings: TimelineViewStateBindings
 }
@@ -196,6 +198,7 @@ enum TimelineAlertInfoType: Hashable {
     case pollEndConfirmation(String)
     case sendingFailed
     case encryptionAuthenticity(String)
+    case encryptionForwarder(String)
 }
 
 struct RoomMemberState {

ElementX/Sources/Screens/Timeline/TimelineViewModel.swift

@@ -107,6 +107,7 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
                                                        emojiProvider: emojiProvider,
                                                        linkMetadataProvider: hideTimelineMedia ? nil : linkMetadataProvider,
                                                        mapTilerConfiguration: appSettings.mapTilerConfiguration,
+                                                       enableKeyShareOnInvite: appSettings.enableKeyShareOnInvite,
                                                        bindings: .init(reactionsCollapsed: [:])),
                    mediaProvider: userSession.mediaProvider)
         
@@ -674,6 +675,8 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
             actionsSubject.send(.displayResolveSendFailure(failure: failure,
                                                            sendHandle: sendHandle))
             
+        } else if let forwarderMessage = eventTimelineItem.properties.encryptionForwarder?.message {
+            displayAlert(.encryptionForwarder(forwarderMessage))
         } else if let authenticityMessage = eventTimelineItem.properties.encryptionAuthenticity?.message {
             displayAlert(.encryptionAuthenticity(authenticityMessage))
         }
@@ -1003,6 +1006,14 @@ class TimelineViewModel: TimelineViewModelType, TimelineViewModelProtocol {
             state.bindings.alertInfo = .init(id: type,
                                              title: message,
                                              primaryButton: .init(title: L10n.actionOk, action: nil))
+        case .encryptionForwarder(let message):
+            state.bindings.alertInfo = .init(id: type,
+                                             title: message,
+                                             primaryButton: .init(title: L10n.actionOk, action: nil),
+                                             secondaryButton: .init(title: L10n.actionLearnMore) { [weak self] in
+                                                 guard let self else { return }
+                                                 appMediator.open(appSettings.historySharingDetailsURL)
+                                             })
         }
     }
     

ElementX/Sources/Screens/Timeline/View/Style/TimelineItemBubbledStylerView.swift

@@ -322,11 +322,18 @@ private extension View {
     }
 }
 
+private extension TimelineItemKeyForwarder {
+    static var test: TimelineItemKeyForwarder {
+        TimelineItemKeyForwarder(id: "@alice:matrix.org", displayName: "alice")
+    }
+}
+
 // MARK: - Previews
 
 struct TimelineItemBubbledStylerView_Previews: PreviewProvider, TestablePreview {
     static let viewModel: TimelineViewModel = {
         let appSettings = AppSettings()
+        appSettings.enableKeyShareOnInvite = true
         appSettings.threadsEnabled = true
         
         let roomProxy = JoinedRoomProxyMock(.init())
@@ -385,6 +392,9 @@ struct TimelineItemBubbledStylerView_Previews: PreviewProvider, TestablePreview
             .padding(.bottom, 20)
         encryptionAuthenticity
             .previewDisplayName("Encryption Indicators")
+        encryptionForwarder
+            .previewLayout(.sizeThatFits)
+            .previewDisplayName("Encryption Forwarder Info")
         pinned
             .previewDisplayName("Pinned messages")
             .previewLayout(.fixed(width: 390, height: 1150))
@@ -540,6 +550,82 @@ struct TimelineItemBubbledStylerView_Previews: PreviewProvider, TestablePreview
         .environmentObject(viewModel.context)
         .environment(\.timelineContext, viewModel.context)
     }
+    
+    static var encryptionForwarder: some View {
+        VStack(spacing: 0) {
+            RoomTimelineItemView(viewState: .init(item: TextRoomTimelineItem(id: .randomEvent,
+                                                                             timestamp: .mock,
+                                                                             isOutgoing: true,
+                                                                             isEditable: false,
+                                                                             canBeRepliedTo: true,
+                                                                             sender: .init(id: "whoever"),
+                                                                             content: .init(body: "A long message that should be on multiple lines."),
+                                                                             properties: RoomTimelineItemProperties(isEdited: true, encryptionForwarder: .test)),
+                                                  groupStyle: .single))
+            
+            RoomTimelineItemView(viewState: .init(item: TextRoomTimelineItem(id: .randomEvent,
+                                                                             timestamp: .mock,
+                                                                             isOutgoing: true,
+                                                                             isEditable: false,
+                                                                             canBeRepliedTo: true,
+                                                                             sender: .init(id: "whoever"),
+                                                                             content: .init(body: "A long message that should be on multiple lines."),
+                                                                             properties: RoomTimelineItemProperties(encryptionForwarder: .test)),
+                                                  groupStyle: .single))
+            
+            RoomTimelineItemView(viewState: .init(item: TextRoomTimelineItem(id: .randomEvent,
+                                                                             timestamp: .mock,
+                                                                             isOutgoing: false,
+                                                                             isEditable: false,
+                                                                             canBeRepliedTo: true,
+                                                                             sender: .init(id: "whoever"),
+                                                                             content: .init(body: "Short message"),
+                                                                             properties: RoomTimelineItemProperties(encryptionForwarder: .test)),
+                                                  groupStyle: .first))
+            
+            RoomTimelineItemView(viewState: .init(item: TextRoomTimelineItem(id: .randomEvent,
+                                                                             timestamp: .mock,
+                                                                             isOutgoing: false,
+                                                                             isEditable: false,
+                                                                             canBeRepliedTo: true,
+                                                                             sender: .init(id: "whoever"),
+                                                                             content: .init(body: "Message goes Here"),
+                                                                             properties: RoomTimelineItemProperties(encryptionForwarder: .test)),
+                                                  groupStyle: .last))
+            
+            ImageRoomTimelineView(timelineItem: ImageRoomTimelineItem(id: .randomEvent,
+                                                                      timestamp: .mock,
+                                                                      isOutgoing: false,
+                                                                      isEditable: false,
+                                                                      canBeRepliedTo: true,
+                                                                      sender: .init(id: "Bob"),
+                                                                      content: .init(filename: "other.png",
+                                                                                     imageInfo: .mockImage,
+                                                                                     thumbnailInfo: nil),
+                                                                      properties: RoomTimelineItemProperties(encryptionForwarder: .test)))
+            
+            VoiceMessageRoomTimelineView(timelineItem: .init(id: .randomEvent,
+                                                             timestamp: .mock,
+                                                             isOutgoing: true,
+                                                             isEditable: false,
+                                                             canBeRepliedTo: true,
+                                                             sender: .init(id: ""),
+                                                             content: .init(filename: "audio.ogg",
+                                                                            duration: 100,
+                                                                            waveform: EstimatedWaveform.mockWaveform,
+                                                                            source: nil,
+                                                                            fileSize: nil,
+                                                                            contentType: nil),
+                                                             properties: RoomTimelineItemProperties(isThreaded: true,
+                                                                                                    encryptionForwarder: .test)),
+                                         playerState: AudioPlayerState(id: .timelineItemIdentifier(.randomEvent),
+                                                                       title: L10n.commonVoiceMessage,
+                                                                       duration: 10,
+                                                                       waveform: EstimatedWaveform.mockWaveform))
+        }
+        .environmentObject(viewModel.context)
+        .environment(\.timelineContext, viewModel.context)
+    }
 }
 
 private struct MockTimelineContent: View {

ElementX/Sources/Screens/Timeline/View/Style/TimelineItemSendInfoLabel.swift

@@ -15,7 +15,8 @@ extension View {
                               adjustedDeliveryStatus: TimelineItemDeliveryStatus?,
                               context: TimelineViewModel.Context) -> some View {
         modifier(TimelineItemSendInfoModifier(sendInfo: .init(timelineItem: timelineItem,
-                                                              adjustedDeliveryStatus: adjustedDeliveryStatus),
+                                                              adjustedDeliveryStatus: adjustedDeliveryStatus,
+                                                              enableKeyShareOnInvite: context.viewState.enableKeyShareOnInvite),
                                               context: context))
     }
 }
@@ -60,6 +61,7 @@ private struct TimelineItemSendInfoLabel: View {
         switch sendInfo.status {
         case .sendingFailed: \.errorSolid
         case .encryptionAuthenticity(let authenticity): authenticity.icon
+        case .encryptionForwarder: \.info
         case .none: nil
         }
     }
@@ -68,6 +70,7 @@ private struct TimelineItemSendInfoLabel: View {
         switch sendInfo.status {
         case .sendingFailed: L10n.commonSendingFailed
         case .encryptionAuthenticity(let authenticity): authenticity.message
+        case .encryptionForwarder(let forwarder): forwarder.message
         case .none: nil
         }
     }
@@ -111,7 +114,11 @@ private struct TimelineItemSendInfoLabel: View {
 
 /// All the data needed to render a timeline item's send info label.
 private struct TimelineItemSendInfo {
-    enum Status { case sendingFailed, encryptionAuthenticity(EncryptionAuthenticity) }
+    enum Status {
+        case sendingFailed
+        case encryptionAuthenticity(EncryptionAuthenticity)
+        case encryptionForwarder(TimelineItemKeyForwarder)
+    }
     
     /// Describes how the content and the send info should be arranged inside a bubble
     enum LayoutType {
@@ -131,6 +138,8 @@ private struct TimelineItemSendInfo {
             .compound.textCriticalPrimary
         case .encryptionAuthenticity(let authenticity):
             authenticity.foregroundStyle
+        case .encryptionForwarder:
+            .compound.textSecondary
         case .none:
             .compound.textSecondary
         }
@@ -138,7 +147,7 @@ private struct TimelineItemSendInfo {
 }
 
 private extension TimelineItemSendInfo {
-    init(timelineItem: EventBasedTimelineItemProtocol, adjustedDeliveryStatus: TimelineItemDeliveryStatus?) {
+    init(timelineItem: EventBasedTimelineItemProtocol, adjustedDeliveryStatus: TimelineItemDeliveryStatus?, enableKeyShareOnInvite: Bool) {
         itemID = timelineItem.id
         localizedString = timelineItem.localizedSendInfo
         
@@ -146,6 +155,8 @@ private extension TimelineItemSendInfo {
             .sendingFailed
         } else if let authenticity = timelineItem.properties.encryptionAuthenticity {
             .encryptionAuthenticity(authenticity)
+        } else if enableKeyShareOnInvite, let forwarder = timelineItem.properties.encryptionForwarder {
+            .encryptionForwarder(forwarder)
         } else {
             nil
         }
@@ -184,6 +195,12 @@ private extension EncryptionAuthenticity {
     }
 }
 
+private extension TimelineItemKeyForwarder {
+    static var test: TimelineItemKeyForwarder {
+        TimelineItemKeyForwarder(id: "@alice:matrix.org", displayName: "alice")
+    }
+}
+
 // MARK: - Previews
 
 struct TimelineItemSendInfoLabel_Previews: PreviewProvider, TestablePreview {
@@ -208,6 +225,10 @@ struct TimelineItemSendInfoLabel_Previews: PreviewProvider, TestablePreview {
                                                       localizedString: "09:47 AM",
                                                       status: .encryptionAuthenticity(.sentInClear(color: .red)),
                                                       layoutType: .horizontal()))
+            TimelineItemSendInfoLabel(sendInfo: .init(itemID: .randomEvent,
+                                                      localizedString: "09:47 AM",
+                                                      status: .encryptionForwarder(.test),
+                                                      layoutType: .horizontal()))
         }
     }
 }

ElementX/Sources/Services/Timeline/TimelineItemContent/RoomTimelineItemProperties.swift

@@ -26,4 +26,6 @@ struct RoomTimelineItemProperties: Hashable {
     var orderedReadReceipts: [ReadReceipt] = []
     /// Authenticity warnings for item's sent in encrypted rooms.
     var encryptionAuthenticity: EncryptionAuthenticity?
+    /// Information about the forwarder of the keys used to decrypt this message.
+    var encryptionForwarder: TimelineItemKeyForwarder?
 }

ElementX/Sources/Services/Timeline/TimelineItemContent/TimelineItemKeyForwarder.swift

@@ -0,0 +1,38 @@
+//
+// Copyright 2026 Element Creations Ltd.
+//
+// SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial.
+// Please see LICENSE files in the repository root for full details.
+//
+
+import MatrixRustSDK
+import SwiftUI
+
+struct TimelineItemKeyForwarder: Identifiable, Hashable {
+    let id: String
+    let displayName: String?
+    
+    init(id: String, displayName: String? = nil) {
+        self.id = id
+        self.displayName = displayName
+    }
+    
+    init(forwarderID: String, forwarderProfile: ProfileDetails) {
+        switch forwarderProfile {
+        case let .ready(displayName, _, _):
+            self.init(id: forwarderID,
+                      displayName: displayName)
+        default:
+            self.init(id: forwarderID,
+                      displayName: nil)
+        }
+    }
+    
+    var message: String {
+        if let displayName {
+            L10n.cryptoEventKeyForwardedKnownProfileDialogContent(displayName, id)
+        } else {
+            L10n.cryptoEventKeyForwardedUnknownProfileDialogContent(id)
+        }
+    }
+}

ElementX/Sources/Services/Timeline/TimelineItemProxy.swift

@@ -110,6 +110,13 @@ class EventTimelineItemProxy {
     
     lazy var sender = TimelineItemSender(senderID: item.sender, senderProfile: item.senderProfile)
     
+    lazy var forwarder: TimelineItemKeyForwarder? = {
+        guard let forwarderID = item.forwarder, let forwarderProfile = item.forwarderProfile else {
+            return nil
+        }
+        return TimelineItemKeyForwarder(forwarderID: forwarderID, forwarderProfile: forwarderProfile)
+    }()
+    
     lazy var timestamp = Date(timeIntervalSince1970: TimeInterval(item.timestamp / 1000))
     
     lazy var debugInfo: TimelineItemDebugInfo = {

ElementX/Sources/Services/Timeline/TimelineItems/EventBasedTimelineItemProtocol.swift

@@ -44,7 +44,7 @@ extension EventBasedTimelineItemProtocol {
     }
     
     var hasStatusIcon: Bool {
-        hasFailedToSend || properties.encryptionAuthenticity != nil
+        hasFailedToSend || properties.encryptionAuthenticity != nil || properties.encryptionForwarder != nil
     }
     
     var hasFailedToSend: Bool {

ElementX/Sources/Services/Timeline/TimelineItems/RoomTimelineItemFactory.swift

@@ -126,7 +126,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                deliveryStatus: eventItemProxy.deliveryStatus,
                                                orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                               encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                               encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                               encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildImageTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -149,7 +150,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                 reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                 deliveryStatus: eventItemProxy.deliveryStatus,
                                                 orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildVideoTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -172,7 +174,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                 reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                 deliveryStatus: eventItemProxy.deliveryStatus,
                                                 orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildAudioTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -195,7 +198,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                 reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                 deliveryStatus: eventItemProxy.deliveryStatus,
                                                 orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildVoiceTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -217,7 +221,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                        reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                        deliveryStatus: eventItemProxy.deliveryStatus,
                                                        orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                       encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                       encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                       encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildFileTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -240,7 +245,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                deliveryStatus: eventItemProxy.deliveryStatus,
                                                orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                               encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                               encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                               encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildNoticeTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -262,7 +268,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                  reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                  deliveryStatus: eventItemProxy.deliveryStatus,
                                                  orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                 encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                 encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                 encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildEmoteTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -284,7 +291,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                 reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                 deliveryStatus: eventItemProxy.deliveryStatus,
                                                 orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildLocationTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -306,7 +314,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                    reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                    deliveryStatus: eventItemProxy.deliveryStatus,
                                                    orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                   encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                   encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                   encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildGalleryTimelineItem(for eventItemProxy: EventTimelineItemProxy,
@@ -329,7 +338,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                deliveryStatus: eventItemProxy.deliveryStatus,
                                                orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                               encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                               encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                               encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildStickerTimelineItem(_ eventItemProxy: EventTimelineItemProxy,
@@ -355,7 +365,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                          reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                          deliveryStatus: eventItemProxy.deliveryStatus,
                                                          orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                         encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                         encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                         encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildPollTimelineItem(_ eventItemProxy: EventTimelineItemProxy,
@@ -415,7 +426,8 @@ struct RoomTimelineItemFactory: RoomTimelineItemFactoryProtocol {
                                                       reactions: buildAggregatedReactions(messageLikeContent.reactions),
                                                       deliveryStatus: eventItemProxy.deliveryStatus,
                                                       orderedReadReceipts: buildOrderedReadReceipts(eventItemProxy.readReceipts),
-                                                      encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState)))
+                                                      encryptionAuthenticity: buildEncryptionAuthenticity(eventItemProxy.shieldState),
+                                                      encryptionForwarder: eventItemProxy.forwarder))
     }
     
     private func buildRedactedTimelineItem(_ eventItemProxy: EventTimelineItemProxy,

PreviewTests/Sources/__Snapshots__/PreviewTests/timelineItemBubbledStylerView.Encryption-Forwarder-Info-iPad-en-GB.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
+oid sha256:55908ffa46570a989039410f9e056afdb8211ce421247d3e19104b7218293b93
+size 1203308

PreviewTests/Sources/__Snapshots__/PreviewTests/timelineItemBubbledStylerView.Encryption-Forwarder-Info-iPad-pseudo.png

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+size 1205155

PreviewTests/Sources/__Snapshots__/PreviewTests/timelineItemBubbledStylerView.Encryption-Forwarder-Info-iPhone-en-GB.png

@@ -0,0 +1,3 @@
+version https://git-lfs.github.com/spec/v1
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+size 613179

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+size 615896

PreviewTests/Sources/__Snapshots__/PreviewTests/timelineItemSendInfoLabel.iPad-en-GB-0.png

@@ -1,3 +1,3 @@
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-size 81888
+size 85032

PreviewTests/Sources/__Snapshots__/PreviewTests/timelineItemSendInfoLabel.iPad-pseudo-0.png

@@ -1,3 +1,3 @@
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-size 81888
+size 85032

PreviewTests/Sources/__Snapshots__/PreviewTests/timelineItemSendInfoLabel.iPhone-en-GB-0.png

@@ -1,3 +1,3 @@
 version https://git-lfs.github.com/spec/v1
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UnitTests/Sources/TimelineViewModelTests.swift

@@ -527,6 +527,36 @@ class TimelineViewModelTests: XCTestCase {
         try await deferred.fulfill()
     }
     
+    // MARK: - Tap Actions
+    
+    func testTapSendInfoEncryptionAuthentictyDisplaysAlert() {
+        // Given a room with an event whose authenticity could not be verified
+        let items = [TextRoomTimelineItem(eventID: "t1", encryptionAuthenticity: .verificationViolation(color: .red))]
+        let timelineController = MockTimelineController()
+        timelineController.timelineItems = items
+        let viewModel = makeViewModel(timelineController: timelineController)
+        
+        XCTAssertNil(viewModel.state.bindings.alertInfo)
+        
+        viewModel.process(viewAction: .itemSendInfoTapped(itemID: items[0].id))
+        
+        XCTAssertEqual(viewModel.state.bindings.alertInfo?.title, "Encrypted by a previously-verified user.")
+    }
+    
+    func testTapSendInfoEncryptionForwarderDisplaysAlert() {
+        // Given a room with an event whose key was forwarded
+        let items = [TextRoomTimelineItem(eventID: "t1", keyForwarder: .test)]
+        let timelineController = MockTimelineController()
+        timelineController.timelineItems = items
+        let viewModel = makeViewModel(timelineController: timelineController)
+        
+        XCTAssertNil(viewModel.state.bindings.alertInfo)
+        
+        viewModel.process(viewAction: .itemSendInfoTapped(itemID: items[0].id))
+        
+        XCTAssertEqual(viewModel.state.bindings.alertInfo?.title, "alice (@alice:matrix.org) shared this message since you were not in the room when it was sent.")
+    }
+    
     // MARK: - Helpers
     
     private func makeViewModel(roomProxy: JoinedRoomProxyProtocol? = nil,
@@ -579,6 +609,32 @@ private extension TextRoomTimelineItem {
     }
 }
 
+private extension TextRoomTimelineItem {
+    init(eventID: String, keyForwarder: TimelineItemKeyForwarder) {
+        self.init(id: .event(uniqueID: .init(UUID().uuidString), eventOrTransactionID: .eventID(eventID)),
+                  timestamp: .mock,
+                  isOutgoing: false,
+                  isEditable: false,
+                  canBeRepliedTo: true,
+                  sender: .init(id: ""),
+                  content: .init(body: "Hello, World!"),
+                  properties: RoomTimelineItemProperties(encryptionForwarder: keyForwarder))
+    }
+}
+
+private extension TextRoomTimelineItem {
+    init(eventID: String, encryptionAuthenticity: EncryptionAuthenticity) {
+        self.init(id: .event(uniqueID: .init(UUID().uuidString), eventOrTransactionID: .eventID(eventID)),
+                  timestamp: .mock,
+                  isOutgoing: false,
+                  isEditable: false,
+                  canBeRepliedTo: true,
+                  sender: .init(id: ""),
+                  content: .init(body: "Hello, World!"),
+                  properties: RoomTimelineItemProperties(encryptionAuthenticity: encryptionAuthenticity))
+    }
+}
+
 private extension TimelineItemSender {
     init(with proxy: RoomMemberProxyMock) {
         self.init(id: proxy.userID,
@@ -587,3 +643,9 @@ private extension TimelineItemSender {
                   avatarURL: proxy.avatarURL)
     }
 }
+
+private extension TimelineItemKeyForwarder {
+    static var test: TimelineItemKeyForwarder {
+        TimelineItemKeyForwarder(id: "@alice:matrix.org", displayName: "alice")
+    }
+}