Use remote authentication, add key display screen

Sesame.xcodeproj/project.pbxproj

@@ -20,8 +20,11 @@
 		E24EE77427FF95920011CFD2 /* DeviceResponse.swift in Sources */ = {isa = PBXBuildFile; fileRef = E24EE77327FF95920011CFD2 /* DeviceResponse.swift */; };
 		E24EE77727FF95C00011CFD2 /* NIOCore in Frameworks */ = {isa = PBXBuildFile; productRef = E24EE77627FF95C00011CFD2 /* NIOCore */; };
 		E24EE77927FF95E00011CFD2 /* Message.swift in Sources */ = {isa = PBXBuildFile; fileRef = E24EE77827FF95E00011CFD2 /* Message.swift */; };
+		E28DED2D281E840B00259690 /* KeyView.swift in Sources */ = {isa = PBXBuildFile; fileRef = E28DED2C281E840B00259690 /* KeyView.swift */; };
+		E28DED2F281E8A0500259690 /* SingleKeyView.swift in Sources */ = {isa = PBXBuildFile; fileRef = E28DED2E281E8A0500259690 /* SingleKeyView.swift */; };
 		E2C5C1DB2806FE8900769EF6 /* RouteAPI.swift in Sources */ = {isa = PBXBuildFile; fileRef = E2C5C1DA2806FE8900769EF6 /* RouteAPI.swift */; };
 		E2C5C1DD281B3AC400769EF6 /* UInt32+Extensions.swift in Sources */ = {isa = PBXBuildFile; fileRef = E2C5C1DC281B3AC400769EF6 /* UInt32+Extensions.swift */; };
+		E2C5C1F8281E769F00769EF6 /* ServerMessage.swift in Sources */ = {isa = PBXBuildFile; fileRef = E2C5C1F7281E769F00769EF6 /* ServerMessage.swift */; };
 /* End PBXBuildFile section */
 
 /* Begin PBXFileReference section */
@@ -38,8 +41,11 @@
 		E24EE77127FDCCC00011CFD2 /* Data+Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "Data+Extensions.swift"; sourceTree = "<group>"; };
 		E24EE77327FF95920011CFD2 /* DeviceResponse.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = DeviceResponse.swift; sourceTree = "<group>"; };
 		E24EE77827FF95E00011CFD2 /* Message.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = Message.swift; sourceTree = "<group>"; };
+		E28DED2C281E840B00259690 /* KeyView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = KeyView.swift; sourceTree = "<group>"; };
+		E28DED2E281E8A0500259690 /* SingleKeyView.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = SingleKeyView.swift; sourceTree = "<group>"; };
 		E2C5C1DA2806FE8900769EF6 /* RouteAPI.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = RouteAPI.swift; sourceTree = "<group>"; };
 		E2C5C1DC281B3AC400769EF6 /* UInt32+Extensions.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = "UInt32+Extensions.swift"; sourceTree = "<group>"; };
+		E2C5C1F7281E769F00769EF6 /* ServerMessage.swift */ = {isa = PBXFileReference; lastKnownFileType = sourcecode.swift; path = ServerMessage.swift; sourceTree = "<group>"; };
 /* End PBXFileReference section */
 
 /* Begin PBXFrameworksBuildPhase section */
@@ -76,11 +82,12 @@
 				E2C5C1D92806FE4A00769EF6 /* API */,
 				884A45B6279F48C100D6E650 /* SesameApp.swift */,
 				884A45B8279F48C100D6E650 /* ContentView.swift */,
+				E28DED2C281E840B00259690 /* KeyView.swift */,
+				E28DED2E281E8A0500259690 /* SingleKeyView.swift */,
 				884A45CC27A465F500D6E650 /* Client.swift */,
 				884A45C827A43D7900D6E650 /* ClientState.swift */,
 				884A45C4279F4BBE00D6E650 /* KeyManagement.swift */,
 				884A45CA27A464C000D6E650 /* SymmetricKey+Extensions.swift */,
-				E24EE77127FDCCC00011CFD2 /* Data+Extensions.swift */,
 				884A45BA279F48C300D6E650 /* Assets.xcassets */,
 				884A45BC279F48C300D6E650 /* Preview Content */,
 			);
@@ -98,10 +105,12 @@
 		E2C5C1D92806FE4A00769EF6 /* API */ = {
 			isa = PBXGroup;
 			children = (
+				E24EE77127FDCCC00011CFD2 /* Data+Extensions.swift */,
 				E24EE77327FF95920011CFD2 /* DeviceResponse.swift */,
 				E24EE77827FF95E00011CFD2 /* Message.swift */,
 				884A45CE27A5402D00D6E650 /* MessageResult.swift */,
 				E2C5C1DA2806FE8900769EF6 /* RouteAPI.swift */,
+				E2C5C1F7281E769F00769EF6 /* ServerMessage.swift */,
 				E2C5C1DC281B3AC400769EF6 /* UInt32+Extensions.swift */,
 			);
 			path = API;
@@ -185,6 +194,7 @@
 			files = (
 				884A45CF27A5402D00D6E650 /* MessageResult.swift in Sources */,
 				884A45B9279F48C100D6E650 /* ContentView.swift in Sources */,
+				E28DED2F281E8A0500259690 /* SingleKeyView.swift in Sources */,
 				E2C5C1DB2806FE8900769EF6 /* RouteAPI.swift in Sources */,
 				E2C5C1DD281B3AC400769EF6 /* UInt32+Extensions.swift in Sources */,
 				884A45CD27A465F500D6E650 /* Client.swift in Sources */,
@@ -193,8 +203,10 @@
 				884A45CB27A464C000D6E650 /* SymmetricKey+Extensions.swift in Sources */,
 				E24EE77927FF95E00011CFD2 /* Message.swift in Sources */,
 				884A45C927A43D7900D6E650 /* ClientState.swift in Sources */,
+				E28DED2D281E840B00259690 /* KeyView.swift in Sources */,
 				884A45B7279F48C100D6E650 /* SesameApp.swift in Sources */,
 				884A45C5279F4BBE00D6E650 /* KeyManagement.swift in Sources */,
+				E2C5C1F8281E769F00769EF6 /* ServerMessage.swift in Sources */,
 			);
 			runOnlyForDeploymentPostprocessing = 0;
 		};

Sesame/API/DeviceResponse.swift

@@ -16,6 +16,11 @@ struct DeviceResponse {
         .init(event: .deviceNotConnected)
     }
 
+    /// Shorthand property for a connected event.
+    static var deviceConnected: DeviceResponse {
+        .init(event: .deviceConnected)
+    }
+
     /// Shorthand property for an unexpected socket event.
     static var unexpectedSocketEvent: DeviceResponse {
         .init(event: .unexpectedSocketEvent)

Sesame/API/Message.swift

@@ -101,6 +101,10 @@ extension Message {
         mac + content.encoded
     }
 
+    var bytes: [UInt8] {
+        Array(encoded)
+    }
+
     /**
      Create a message from received bytes.
      - Parameter data: The sequence of bytes

Sesame/API/MessageResult.swift

@@ -38,6 +38,9 @@ enum MessageResult: UInt8 {
 
     /// Another message is being processed by the device
     case operationInProgress = 14
+
+    /// The device is connected
+    case deviceConnected = 15
 }
 
 extension MessageResult: CustomStringConvertible {
@@ -66,6 +69,8 @@ extension MessageResult: CustomStringConvertible {
             return "The device did not respond"
         case .operationInProgress:
             return "Another operation is in progress"
+        case .deviceConnected:
+            return "The device is connected"
         }
     }
 }

Sesame/API/ServerMessage.swift

@@ -0,0 +1,51 @@
+import Foundation
+import NIOCore
+
+#if canImport(CryptoKit)
+import CryptoKit
+#else
+import Crypto
+#endif
+
+struct ServerMessage {
+
+    static let authTokenSize = SHA256.byteCount
+
+    static let length = authTokenSize + Message.length
+
+    let authToken: Data
+
+    let message: Message
+
+    init(authToken: Data, message: Message) {
+        self.authToken = authToken
+        self.message = message
+    }
+    
+    /**
+     Decode a message from a byte buffer.
+     The buffer must contain at least `ServerMessage.length` bytes, or it will return `nil`.
+     - Parameter buffer: The buffer containing the bytes.
+     */
+    init?(decodeFrom buffer: ByteBuffer) {
+        guard let data = buffer.getBytes(at: 0, length: ServerMessage.length) else {
+            return nil
+        }
+        self.authToken = Data(data.prefix(ServerMessage.authTokenSize))
+        self.message = Message(decodeFrom: Data(data.dropFirst(ServerMessage.authTokenSize)))
+    }
+
+    var encoded: Data {
+        authToken + message.encoded
+    }
+
+    static func token(from buffer: ByteBuffer) -> Data? {
+        guard buffer.readableBytes == authTokenSize else {
+            return nil
+        }
+        guard let bytes = buffer.getBytes(at: 0, length: authTokenSize) else {
+            return nil
+        }
+        return Data(bytes)
+    }
+}

Sesame/Client.swift

@@ -11,40 +11,19 @@ struct Client {
         self.server = server
     }
 
-    private enum RequestReponse: Error {
+    func deviceStatus(authToken: Data) async -> ClientState {
-        case requestFailed
+        await send(path: .getDeviceStatus, data: authToken).state
-        case unknownResponseData(Data)
-        case unknownResponseString(String)
-        case success(UInt8)
     }
     
-    func deviceStatus() async -> ClientState {
+    func send(_ message: Message, authToken: Data) async -> (state: ClientState, response: Message?) {
-        let url = server.appendingPathComponent(RouteAPI.getDeviceStatus.rawValue)
+        let serverMessage = ServerMessage(authToken: authToken, message: message)
-        let request = URLRequest(url: url, cachePolicy: .reloadIgnoringLocalCacheData)
+        return await send(path: .postMessage, data: serverMessage.encoded)
-        let response = await integerReponse(to: request)
-        switch response {
-        case .requestFailed:
-            return .deviceNotAvailable(.serverNotReached)
-        case .unknownResponseData(let data):
-            return .internalError("Unknown status (\(data.count) bytes)")
-        case .unknownResponseString(let string):
-            return .internalError("Unknown status (\(string.prefix(15)))")
-        case .success(let int):
-            switch int {
-            case 0:
-                return .deviceNotAvailable(.deviceDisconnected)
-            case 1:
-                return .ready
-            default:
-                return .internalError("Invalid status: \(int)")
-            }
-        }
     }
 
-    func send(_ message: Message) async throws -> (state: ClientState, response: Message?) {
+    private func send(path: RouteAPI, data: Data) async -> (state: ClientState, response: Message?) {
-        let url = server.appendingPathComponent(RouteAPI.postMessage.rawValue)
+        let url = server.appendingPathComponent(path.rawValue)
         var request = URLRequest(url: url)
-        request.httpBody = message.encoded
+        request.httpBody = data
         request.httpMethod = "POST"
         guard let data = await fulfill(request) else {
             return (.deviceNotAvailable(.serverNotReached), nil)
@@ -81,22 +60,6 @@ struct Client {
             return nil
         }
     }
-    
-    private func integerReponse(to request: URLRequest) async -> RequestReponse {
-        guard let data = await fulfill(request) else {
-            return .requestFailed
-        }
-        guard let string = String(data: data, encoding: .utf8) else {
-            print("Unexpected device status data: \([UInt8](data))")
-            return .unknownResponseData(data)
-        }
-        guard let int = UInt8(string) else {
-            print("Unexpected device status '\(string)'")
-            return .unknownResponseString(string)
-        }
-        return .success(int)
-    }
-    
 }
 
 class NeverCacheDelegate: NSObject, NSURLConnectionDataDelegate {

Sesame/ClientState.swift

@@ -93,16 +93,13 @@ enum ClientState {
             self = .deviceNotAvailable(.deviceDisconnected)
         case .operationInProgress:
             self = .waitingForResponse
+        case .deviceConnected:
+            self = .ready
         }
     }
 
     var actionText: String {
-        switch self {
+        "Unlock"
-        case .noKeyAvailable:
-            return "Create key"
-        default:
-            return "Unlock"
-        }
     }
 
     var requiresDescription: Bool {
@@ -137,7 +134,7 @@ enum ClientState {
     
     var allowsAction: Bool {
         switch self {
-        case .requestingStatus, .deviceNotAvailable, .waitingForResponse:
+        case .requestingStatus, .deviceNotAvailable, .waitingForResponse, .noKeyAvailable:
             return false
         default:
             return true

Sesame/ContentView.swift

@@ -8,6 +8,9 @@ struct ContentView: View {
     @AppStorage("counter")
     var nextMessageCounter: Int = 0
 
+    @State
+    var keyManager = KeyManagement()
+    
     @State
     var state: ClientState = .noKeyAvailable
 
@@ -20,6 +23,12 @@ struct ContentView: View {
     @State
     private var responseTime: Date? = nil
 
+    @State
+    private var showKeySheet = false
+
+    @State
+    private var showHistorySheet = false
+
     var isPerformingRequests: Bool {
         hasActiveRequest ||
         state == .waitingForResponse
@@ -28,7 +37,7 @@ struct ContentView: View {
     var buttonBackground: Color {
         state.allowsAction ?
             .white.opacity(0.2) :
-            .gray.opacity(0.2)
+            .black.opacity(0.2)
     }
 
     let buttonBorderWidth: CGFloat = 3
@@ -39,16 +48,44 @@ struct ContentView: View {
 
     private let buttonWidth: CGFloat = 250
 
+    private let smallButtonHeight: CGFloat = 50
+
+    private let smallButtonWidth: CGFloat = 120
+
+    private let smallButtonBorderWidth: CGFloat = 1
+
     var body: some View {
         GeometryReader { geo in
             VStack(spacing: 20) {
+                HStack {
+                    Button("History", action: { showHistorySheet = true })
+                        .frame(width: smallButtonWidth,
+                               height: smallButtonHeight)
+                        .background(.white.opacity(0.2))
+                        .cornerRadius(smallButtonHeight / 2)
+                        .overlay(RoundedRectangle(cornerRadius: smallButtonHeight / 2).stroke(lineWidth: smallButtonBorderWidth).foregroundColor(.white))
+                        .foregroundColor(.white)
+                        .font(.title2)
+                        .padding()
+                    Spacer()
+                    Button("Keys", action: { showKeySheet = true })
+                        .frame(width: smallButtonWidth,
+                               height: smallButtonHeight)
+                        .background(.white.opacity(0.2))
+                        .cornerRadius(smallButtonHeight / 2)
+                        .overlay(RoundedRectangle(cornerRadius: smallButtonHeight / 2).stroke(lineWidth: smallButtonBorderWidth).foregroundColor(.white))
+                        .foregroundColor(.white)
+                        .font(.title2)
+                        .padding()
+                }
                 Spacer()
                 if state.requiresDescription {
                     Text(state.description)
                         .padding()
                 }
                 Button(state.actionText, action: mainButtonPressed)
-                    .frame(width: buttonWidth, height: buttonWidth, alignment: .center)
+                    .frame(width: buttonWidth,
+                           height: buttonWidth)
                     .background(buttonBackground)
                     .cornerRadius(buttonWidth / 2)
                     .overlay(RoundedRectangle(cornerRadius: buttonWidth / 2).stroke(lineWidth: buttonBorderWidth).foregroundColor(buttonColor))
@@ -57,8 +94,9 @@ struct ContentView: View {
                     .disabled(!state.allowsAction)
                     .padding(.bottom, (geo.size.width-buttonWidth) / 2)
             }
+            .background(state.color)
             .onAppear {
-                if KeyManagement.hasKey {
+                if keyManager.hasAllKeys {
                     state = .requestingStatus
                 }
                 startRegularStatusUpdates()
@@ -67,20 +105,19 @@ struct ContentView: View {
                 endRegularStatusUpdates()
             }
             .frame(width: geo.size.width, height: geo.size.height)
-            .background(state.color)
             .animation(.easeInOut, value: state.color)
+            .sheet(isPresented: $showKeySheet) {
+                KeyView(keyManager: $keyManager)
+            }
         }
     }
     
     func mainButtonPressed() {
-        guard let key = KeyManagement.key?.remote else {
+        guard let key = keyManager.get(.remoteKey),
-            generateKey()
+              let token = keyManager.get(.authToken)?.data else {
             return
         }
-        sendMessage(using: key)
-    }
 
-    func sendMessage(using key: SymmetricKey) {
         let count = UInt32(nextMessageCounter)
         let now = Date()
         let content = Message.Content(
@@ -90,7 +127,7 @@ struct ContentView: View {
         state = .waitingForResponse
         print("Sending message \(count)")
         Task {
-            let (newState, message) = try await server.send(message)
+            let (newState, message) = await server.send(message, authToken: token)
             responseTime = now
             state = newState
             if let message = message {
@@ -100,7 +137,7 @@ struct ContentView: View {
     }
 
     private func processResponse(_ message: Message, sendTime: Date) {
-        guard let key = KeyManagement.key?.device else {
+        guard let key = keyManager.get(.deviceKey) else {
             return
         }
         guard message.isValid(using: key) else {
@@ -115,9 +152,13 @@ struct ContentView: View {
         let time1 = deviceTime.timeIntervalSince(sendTime)
         let time2 = now.timeIntervalSince(deviceTime)
         if time1 < 0 {
-            print("Device time behind by at least \(Int(-time1 * 1000)) ms behind")
+            print("Device time behind by at least \(Int(-time1 * 1000)) ms")
+            print("Device: \(deviceTime)")
+            print("Remote: \(now)")
         } else if time2 < 0 {
-            print("Device time behind by at least \(Int(-time2 * 1000)) ms ahead")
+            print("Device time ahead by at least \(Int(-time2 * 1000)) ms")
+            print("Device: \(deviceTime)")
+            print("Remote: \(now)")
         } else {
             print("Device time synchronized")
         }
@@ -139,13 +180,16 @@ struct ContentView: View {
     }
     
     func checkDeviceStatus(_ timer: Timer) {
+        guard let authToken = keyManager.get(.authToken) else {
+            return
+        }
         guard !hasActiveRequest else {
             return
         }
         hasActiveRequest = true
         print("Checking device status")
         Task {
-            let newState = await server.deviceStatus()
+            let newState = await server.deviceStatus(authToken: authToken.data)
             hasActiveRequest = false
             switch state {
             case .noKeyAvailable:
@@ -173,16 +217,6 @@ struct ContentView: View {
             }
         }
     }
-    
-    func generateKey() {
-        print("Regenerate key")
-        KeyManagement.generateNewKeys()
-        state = .requestingStatus
-    }
-    
-    func shareKey() {
-        
-    }
 }
 
 struct ContentView_Previews: PreviewProvider {

Sesame/KeyManagement.swift

@@ -2,95 +2,154 @@ import Foundation
 import CryptoKit
 import SwiftUI
 
-final class KeyManagement {
+extension KeyManagement {
 
-    static let tag = "com.ch.sesame.key".data(using: .utf8)!
+    enum KeyType: String, Identifiable, CaseIterable {
 
-    private static let label = "sesame"
+        case deviceKey = "sesame-device"
+        case remoteKey = "sesame-remote"
+        case authToken = "sesame-remote-auth"
 
-    private static let keyType = kSecAttrKeyTypeEC
+        var id: String {
+            rawValue
+        }
 
-    private static let keyClass = kSecAttrKeyClassSymmetric
+        var displayName: String {
+            switch self {
+            case .deviceKey:
+                return "Device Key"
+            case .remoteKey:
+                return "Remote Key"
+            case .authToken:
+                return "Authentication Token"
+            }
+        }
 
-    private static let query: [String: Any] = [
+        var keyLength: SymmetricKeySize {
-        kSecClass as String: kSecClassInternetPassword,
+            .bits256
-        kSecAttrAccount as String: "account",
+        }
-        kSecAttrServer as String: "christophhagen.de",
+    }
-        kSecAttrLabel as String: "sesame"]
+}
 
-    private static func loadKeys() -> Data? {
+extension KeyManagement.KeyType: CustomStringConvertible {
-        var query = query
+
+    var description: String {
+        displayName
+    }
+}
+
+private struct KeyChain {
+
+    private let keyType = kSecAttrKeyTypeEC
+
+    private let keyClass = kSecAttrKeyClassSymmetric
+
+    private let domain: String
+
+    init(domain: String) {
+        self.domain = domain
+    }
+
+    private func baseQuery(for type: KeyManagement.KeyType) -> [String : Any] {
+        [kSecClass as String: kSecClassInternetPassword,
+         kSecAttrAccount as String: type.rawValue,
+         kSecAttrServer as String: domain]
+    }
+
+    func save(_ type: KeyManagement.KeyType, _ key: SymmetricKey) {
+        var query = baseQuery(for: type)
+        query[kSecValueData as String] = key.data
+        let status = SecItemAdd(query as CFDictionary, nil)
+        guard status == errSecSuccess else {
+            print("Failed to store \(type): \(status)")
+            return
+        }
+        print("\(type) saved to keychain")
+    }
+
+    func load(_ type: KeyManagement.KeyType) -> SymmetricKey? {
+        var query = baseQuery(for: type)
         query[kSecReturnData as String] = kCFBooleanTrue
 
         var item: CFTypeRef?
         let status = SecItemCopyMatching(query as CFDictionary, &item)
         guard status == errSecSuccess else {
-            print("Failed to get key: \(status)")
+            print("Failed to get \(type): \(status)")
             return nil
         }
         let key = item as! CFData
-        print("Key loaded from keychain")
+        print("\(type) loaded from keychain")
-        return key as Data
+        return SymmetricKey(data: key as Data)
     }
 
-    private static func deleteKeys() {
+    func delete(_ type: KeyManagement.KeyType) {
-        let status = SecItemDelete(query as CFDictionary)
+        let status = SecItemDelete(baseQuery(for: type) as CFDictionary)
         guard status == errSecSuccess || status == errSecItemNotFound else {
-            print("Failed to remove key: \(status)")
+            print("Failed to remove \(type): \(status)")
             return
         }
-        print("Key removed from keychain")
+        print("\(type) removed from keychain")
     }
 
-    private static func saveKeys(_ data: Data) {
+    func has(_ type: KeyManagement.KeyType) -> Bool {
-        var query = query
+        load(type) != nil
-        query[kSecValueData as String] = data
-        let status = SecItemAdd(query as CFDictionary, nil)
-        guard status == errSecSuccess else {
-            print("Failed to store key: \(status)")
-            return
-        }
-        print("Key saved to keychain")
-    }
-
-    private static var keyData: Data? = loadKeys() {
-        didSet {
-            guard let data = keyData else {
-                deleteKeys()
-                return
-            }
-            saveKeys(data)
     }
 }
 
-    static var hasKey: Bool {
+final class KeyManagement: ObservableObject {
-        key != nil
+
+    private let keyChain: KeyChain
+
+    @Published
+    private(set) var hasRemoteKey = false
+
+    @Published
+    private(set) var hasDeviceKey = false
+
+    @Published
+    private(set) var hasAuthToken = false
+
+    var hasAllKeys: Bool {
+        hasRemoteKey && hasDeviceKey && hasAuthToken
     }
 
-    private(set) static var key: (device: SymmetricKey, remote: SymmetricKey)? {
+    init() {
-        get {
+        self.keyChain = KeyChain(domain: "christophhagen.de")
-            guard let data = keyData else {
+        updateKeyStates()
-                return nil
     }
-            let device = SymmetricKey(data: data.prefix(32))
+
-            let remote = SymmetricKey(data: data.advanced(by: 32))
+    func has(_ type: KeyType) -> Bool {
-            return (device, remote)
+        switch type {
-        }
+        case .deviceKey:
-        set {
+            return hasDeviceKey
-            guard let key = newValue else {
+        case .remoteKey:
-                keyData = nil
+            return hasRemoteKey
-                return
+        case .authToken:
-            }
+            return hasAuthToken
-            keyData = key.device.data + key.remote.data
         }
     }
 
-    static func generateNewKeys() {
+    func get(_ type: KeyType) -> SymmetricKey? {
-        let device = SymmetricKey(size: .bits256)
+        keyChain.load(type)
-        let remote = SymmetricKey(size: .bits256)
+    }
-        key = (device, remote)
+
-        print("New keys:")
+    func delete(_ type: KeyType) {
-        print("Device: \(device.data.hexEncoded)")
+        keyChain.delete(type)
-        print("Remote: \(remote.data.hexEncoded)")
+        updateKeyStates()
+    }
+
+    func generate(_ type: KeyType) {
+        let key = SymmetricKey(size: type.keyLength)
+        if keyChain.has(type) {
+            keyChain.delete(type)
+        }
+        keyChain.save(type, key)
+        updateKeyStates()
+    }
+
+    private func updateKeyStates() {
+        self.hasRemoteKey = keyChain.has(.remoteKey)
+        self.hasDeviceKey = keyChain.has(.deviceKey)
+        self.hasAuthToken = keyChain.has(.authToken)
     }
 }

Sesame/KeyView.swift

@@ -0,0 +1,25 @@
+import SwiftUI
+
+struct KeyView: View {
+
+    @Binding
+    var keyManager: KeyManagement
+
+    var body: some View {
+        GeometryReader { geo in
+            VStack(alignment: .leading, spacing: 16) {
+                ForEach(KeyManagement.KeyType.allCases) { keyType in
+                    SingleKeyView(
+                        keyManager: $keyManager,
+                        type: keyType)
+                }
+            }.padding()
+        }
+    }
+}
+
+struct KeyView_Previews: PreviewProvider {
+    static var previews: some View {
+        KeyView(keyManager: .constant(KeyManagement()))
+    }
+}

Sesame/SingleKeyView.swift

@@ -0,0 +1,54 @@
+import SwiftUI
+
+struct SingleKeyView: View {
+
+    @State
+    private var needRefresh = false
+
+    @Binding
+    var keyManager: KeyManagement
+
+    let type: KeyManagement.KeyType
+
+    private var generateText: String {
+        hasKey ? "Generate" : "Regenerate"
+    }
+
+    var hasKey: Bool {
+        keyManager.has(type)
+    }
+
+    var content: String {
+        keyManager.get(type)?.displayString ?? "-"
+    }
+
+    var body: some View {
+        VStack(alignment: .leading, spacing: 8) {
+            Text(type.displayName)
+                .bold()
+            Text(needRefresh ? content : content)
+                .font(.system(.body, design: .monospaced))
+            HStack() {
+                Button(generateText) {
+                    keyManager.generate(type)
+                    needRefresh.toggle()
+                }
+                .padding()
+                Button("Copy") {
+                    UIPasteboard.general.string = content
+                }
+                .disabled(!hasKey)
+                .padding()
+                Spacer()
+            }
+        }
+    }
+}
+
+struct SingleKeyView_Previews: PreviewProvider {
+    static var previews: some View {
+        SingleKeyView(
+            keyManager: .constant(KeyManagement()),
+            type: .deviceKey)
+    }
+}

Sesame/SymmetricKey+Extensions.swift

@@ -11,6 +11,10 @@ extension SymmetricKey {
         data.base64EncodedString()
     }
 
+    var displayString: String {
+        data.hexEncoded.uppercased().split(by: 4).joined(separator: " ")
+    }
+    
     var codeString: String {
         "    {" +
         withUnsafeBytes {
@@ -19,3 +23,19 @@ extension SymmetricKey {
         "},"
     }
 }
+
+extension String {
+
+    func split(by length: Int) -> [String] {
+        var startIndex = self.startIndex
+        var results = [Substring]()
+
+        while startIndex < self.endIndex {
+            let endIndex = self.index(startIndex, offsetBy: length, limitedBy: self.endIndex) ?? self.endIndex
+            results.append(self[startIndex..<endIndex])
+            startIndex = endIndex
+        }
+
+        return results.map { String($0) }
+    }
+}