Implement mnemonic verification

Signal/src/Loki/Settings/DeviceLinkingModal.swift

@@ -38,7 +38,6 @@ final class DeviceLinkingModal : Modal, DeviceLinkingSessionDelegate {
         let result = UILabel()
         result.textColor = Theme.primaryColor
         result.font = UIFont.ows_dynamicTypeCaption1Clamped
-        result.text = "word word word"
         result.numberOfLines = 0
         result.lineBreakMode = .byWordWrapping
         result.textAlignment = .center
@@ -101,6 +100,10 @@ final class DeviceLinkingModal : Modal, DeviceLinkingSessionDelegate {
             }
         }()
         mnemonicLabel.isHidden = (mode == .master)
+        if mode == .slave {
+            let hexEncodedPublicKey = OWSIdentityManager.shared().identityKeyPair()!.hexEncodedPublicKey
+            mnemonicLabel.text = Mnemonic.encode(hexEncodedString: hexEncodedPublicKey).split(separator: " ")[0..<3].joined(separator: " ")
+        }
         let buttonHeight = cancelButton.button.titleLabel!.font.pointSize * 48 / 17
         authorizeButton.set(.height, to: buttonHeight)
         cancelButton.set(.height, to: buttonHeight)
@@ -114,13 +117,14 @@ final class DeviceLinkingModal : Modal, DeviceLinkingSessionDelegate {
     // MARK: Device Linking
     func requestUserAuthorization(for deviceLink: DeviceLink) {
         self.deviceLink = deviceLink
-        self.topSpacer.isHidden = true
-        self.spinner.stopAnimating()
-        self.spinner.isHidden = true
-        self.titleLabel.text = NSLocalizedString("Linking Request Received", comment: "")
-        self.subtitleLabel.text = NSLocalizedString("Please check that the words below match the words shown on the device being linked.", comment: "")
-        self.mnemonicLabel.isHidden = false
-        self.authorizeButton.isHidden = false
+        topSpacer.isHidden = true
+        spinner.stopAnimating()
+        spinner.isHidden = true
+        titleLabel.text = NSLocalizedString("Linking Request Received", comment: "")
+        subtitleLabel.text = NSLocalizedString("Please check that the words below match the words shown on the device being linked.", comment: "")
+        mnemonicLabel.text = Mnemonic.encode(hexEncodedString: deviceLink.slave.hexEncodedPublicKey).split(separator: " ")[0..<3].joined(separator: " ")
+        mnemonicLabel.isHidden = false
+        authorizeButton.isHidden = false
     }
     
     @objc private func authorizeDeviceLink() {

SignalServiceKit/src/Loki/Messaging/LKDeviceLinkMessage.h

@@ -8,6 +8,7 @@ NS_SWIFT_NAME(DeviceLinkMessage)
 @property (nonatomic, readonly) NSData *masterSignature; // nil for device linking requests
 @property (nonatomic, readonly) NSData *slaveSignature;
 
-- (instancetype)initInThread:(TSThread *)thread masterHexEncodedPublicKey:(NSString *)masterHexEncodedPublicKey slaveHexEncodedPublicKey:(NSString *)slaveHexEncodedPublicKey masterSignature:(NSData *)masterSignature slaveSignature:(NSData *)slaveSignature;
+- (instancetype)initInThread:(TSThread *)thread masterHexEncodedPublicKey:(NSString *)masterHexEncodedPublicKey slaveHexEncodedPublicKey:(NSString *)slaveHexEncodedPublicKey
+    masterSignature:(NSData *)masterSignature slaveSignature:(NSData *)slaveSignature;
 
 @end

SignalServiceKit/src/Loki/Messaging/LKDeviceLinkMessage.m

@@ -7,7 +7,8 @@
 
 @implementation LKDeviceLinkMessage
 
-- (instancetype)initInThread:(TSThread *)thread masterHexEncodedPublicKey:(NSString *)masterHexEncodedPublicKey slaveHexEncodedPublicKey:(NSString *)slaveHexEncodedPublicKey masterSignature:(NSData *)masterSignature slaveSignature:(NSData *)slaveSignature {
+- (instancetype)initInThread:(TSThread *)thread masterHexEncodedPublicKey:(NSString *)masterHexEncodedPublicKey slaveHexEncodedPublicKey:(NSString *)slaveHexEncodedPublicKey
+    masterSignature:(NSData *)masterSignature slaveSignature:(NSData *)slaveSignature {
     self = [self initOutgoingMessageWithTimestamp:NSDate.ows_millisecondTimeStamp inThread:thread messageBody:@"" attachmentIds:[NSMutableArray<NSString *> new]
         expiresInSeconds:0 expireStartedAt:0 isVoiceMessage:NO groupMetaMessage:TSGroupMetaMessageUnspecified quotedMessage:nil contactShare:nil linkPreview:nil];
     if (self) {
@@ -28,7 +29,7 @@
     NSError *error;
     SSKProtoLokiDeviceLinkMessage *deviceLinkMessage = [deviceLinkMessageBuilder buildAndReturnError:&error];
     if (error || deviceLinkMessage == nil) {
-        OWSFailDebug(@"Failed to build device linking message for: %@ due to error: %@", self.masterHexEncodedPublicKey, error);
+        OWSFailDebug(@"Failed to build device link message due to error: %@", error);
     }
     SSKProtoContentBuilder *contentBuilder = [super contentBuilder:recipient];
     [contentBuilder setLokiDeviceLinkMessage:deviceLinkMessage];