Implement Face ID authentication and update iOS configuration for biometric support

docs/IOS_BIOMETRICS.md

@@ -0,0 +1,21 @@
+iOS Biometric / Device Lock Setup
+
+To enable and test device biometric authentication on iOS:
+
+- Ensure the Info.plist contains a Face ID usage description (`NSFaceIDUsageDescription`). This project already adds a default string.
+- Install CocoaPods and native deps:
+
+```sh
+cd ios
+bundle install # (if you use Bundler)
+bundle exec pod install
+```
+
+- Open the workspace in Xcode (`ios/authenticationsdk.xcworkspace`) and build to a device or simulator. For Face ID testing use a simulator with Face ID enabled or a device with Face ID configured.
+- The app uses `react-native-keychain` to prompt for biometrics / device passcode; no additional Xcode entitlements are required beyond the Info.plist usage string.
+
+If biometrics are not available, the Keychain prompt can fall back to the device passcode when configured.
+
+Testing notes:
+- Simulator: Device > Face ID > Enrolled to simulate Face ID responses.
+- Device: Make sure Face ID / Touch ID is configured in Settings.

ios/authenticationsdk/Info.plist

@@ -35,6 +35,8 @@
 	</dict>
 	<key>NSLocationWhenInUseUsageDescription</key>
 	<string></string>
+	<key>NSFaceIDUsageDescription</key>
+	<string>This app uses Face ID to secure access to sensitive features.</string>
 	<key>RCTNewArchEnabled</key>
 	<true/>
 	<key>UILaunchStoryboardName</key>

src/screen/FaceAuth.tsx

@@ -1,16 +1,54 @@
-import React, { useEffect } from "react";
+import React, { useEffect, useState } from "react";
-import { View, Text } from "react-native";
+import { View, Text, Alert } from "react-native";
 import { Camera, useCameraDevices } from "react-native-vision-camera";
 import { useFaceDetector } from "vision-camera-face-detector";
+import * as Keychain from "react-native-keychain";
 
 export default function FaceRecognition() {
+  const [authenticated, setAuthenticated] = useState(false);
   const devices = useCameraDevices();
   const device = devices.front;
 
   useEffect(() => {
     Camera.requestCameraPermission();
+    authenticateWithKeychain();
   }, []);
 
+  async function authenticateWithKeychain() {
+    try {
+      // Try to retrieve a protected generic password which will trigger
+      // the system authentication prompt (Face ID / Touch ID / passcode).
+      const creds = await Keychain.getGenericPassword({
+        authenticationPrompt: { title: "Authenticate to unlock" },
+      });
+
+      if (creds) {
+        setAuthenticated(true);
+        console.log("Authenticated via Keychain, credentials found.");
+        return;
+      }
+
+      // If no credentials stored yet, create one protected by biometrics
+      await Keychain.setGenericPassword("user", "secure-token", {
+        accessControl: Keychain.ACCESS_CONTROL.BIOMETRY_ANY,
+        accessible: Keychain.ACCESSIBLE.WHEN_PASSCODE_SET_THIS_DEVICE_ONLY,
+      });
+
+      // Now request access which will prompt biometric/passcode
+      const creds2 = await Keychain.getGenericPassword({
+        authenticationPrompt: { title: "Authenticate to unlock" },
+      });
+
+      if (creds2) {
+        setAuthenticated(true);
+        console.log("Authenticated after storing credentials.");
+      }
+    } catch (e: any) {
+      console.log("Authentication error:", e);
+      Alert.alert("Authentication failed", e?.message || String(e));
+    }
+  }
+
   const faceDetector = useFaceDetector({
     landmarkMode: "all",
     performanceMode: "fast",
@@ -18,6 +56,13 @@ export default function FaceRecognition() {
 
   if (!device) return <Text>Loading camera...</Text>;
 
+  if (!authenticated)
+    return (
+      <View style={{ flex: 1, justifyContent: "center", alignItems: "center" }}>
+        <Text>Locked. Please authenticate to continue.</Text>
+      </View>
+    );
+
   return (
     <View style={{ flex: 1 }}>
       <Camera