(mobile): ios - calculate hash using CryptoKit (#5976)

* ios: calculate hash using CryptoKit

* chore: remove unused crypto dep

---------

Co-authored-by: shenlong-tanwen <139912620+shalong-tanwen@users.noreply.github.com>
Co-authored-by: Alex Tran <alex.tran1502@gmail.com>

mobile/ios/Runner/BackgroundSync/BackgroundServicePlugin.swift

@@ -8,6 +8,7 @@
 import Flutter
 import BackgroundTasks
 import path_provider_foundation
+import CryptoKit
 
 class BackgroundServicePlugin: NSObject, FlutterPlugin {
     
@@ -102,12 +103,62 @@ class BackgroundServicePlugin: NSObject, FlutterPlugin {
             case "backgroundAppRefreshEnabled":
                 handleBackgroundRefreshStatus(call: call, result: result)
                 break
+            case "digestFiles":
+                handleDigestFiles(call: call, result: result)
+                break
             default:
                 result(FlutterMethodNotImplemented)
                 break
         }
     }
     
+    // Calculates the SHA-1 hash of each file from the list of paths provided
+    func handleDigestFiles(call: FlutterMethodCall, result: @escaping FlutterResult) {
+        
+        let bufsize = 2 * 1024 * 1024
+        // Private error to throw if file cannot be read
+        enum DigestError: String, LocalizedError {
+            case NoFileHandle = "Cannot Open File Handle"
+
+            public var errorDescription: String? { self.rawValue }
+        }
+        
+        // Parse the arguments or else fail
+        guard let args = call.arguments as? Array<String> else {
+            print("Cannot parse args as array: \(String(describing: call.arguments))")
+            result(FlutterError(code: "Malformed",
+                                message: "Received args is not an Array<String>",
+                                details: nil))
+            return
+        }
+        
+        // Compute hash in background thread
+        DispatchQueue.global(qos: .background).async {
+            var hashes: [FlutterStandardTypedData?] = Array(repeating: nil, count: args.count)
+            for i in (0 ..< args.count) {
+                do {
+                    guard let file = FileHandle(forReadingAtPath: args[i]) else { throw DigestError.NoFileHandle }
+                    var hasher = Insecure.SHA1.init();
+                    while autoreleasepool(invoking: {
+                        let chunk = file.readData(ofLength: bufsize)
+                        guard !chunk.isEmpty else { return false } // EOF
+                        hasher.update(data: chunk)
+                        return true // continue
+                    }) { }
+                    let digest = hasher.finalize()
+                    hashes[i] = FlutterStandardTypedData(bytes: Data(Array(digest.makeIterator())))
+                } catch {
+                    print("Cannot calculate the digest of the file \(args[i]) due to \(error.localizedDescription)")
+                }
+            }
+            
+            // Return result in main thread
+            DispatchQueue.main.async {
+                result(Array(hashes))
+            }
+        }
+    }
+    
     // Called by the flutter code when enabled so that we can turn on the backround services
     // and save the callback information to communicate on this method channel
     public func handleBackgroundEnable(call: FlutterMethodCall, result: FlutterResult) {

mobile/lib/modules/backup/background_service/background.service.dart

@@ -132,6 +132,7 @@ class BackgroundService {
     }
   }
 
+  // Yet to be implemented
   Future<Uint8List?> digestFile(String path) {
     return _foregroundChannel.invokeMethod<Uint8List>("digestFile", [path]);
   }

mobile/lib/shared/services/hash.service.dart

@@ -1,7 +1,5 @@
-import 'dart:convert';
 import 'dart:io';
 
-import 'package:crypto/crypto.dart';
 import 'package:flutter/foundation.dart';
 import 'package:hooks_riverpod/hooks_riverpod.dart';
 import 'package:immich_mobile/modules/backup/background_service/background.service.dart';
@@ -119,37 +117,12 @@ class HashService {
   /// Hashes the given files and returns a list of the same length
   /// files that could not be hashed have a `null` value
   Future<List<Uint8List?>> _hashFiles(List<String> paths) async {
-    if (Platform.isAndroid) {
     final List<Uint8List?>? hashes =
         await _backgroundService.digestFiles(paths);
     if (hashes == null) {
       throw Exception("Hashing ${paths.length} files failed");
     }
     return hashes;
-    } else if (Platform.isIOS) {
-      final List<Uint8List?> result = List.filled(paths.length, null);
-      for (int i = 0; i < paths.length; i++) {
-        result[i] = await _hashAssetDart(File(paths[i]));
-      }
-      return result;
-    } else {
-      throw Exception("_hashFiles implementation missing");
-    }
-  }
-
-  /// Hashes a single file using Dart's crypto package
-  Future<Uint8List?> _hashAssetDart(File f) async {
-    late Digest output;
-    final sink = sha1.startChunkedConversion(
-      ChunkedConversionSink<Digest>.withCallback((accumulated) {
-        output = accumulated.first;
-      }),
-    );
-    await for (final chunk in f.openRead()) {
-      sink.add(chunk);
-    }
-    sink.close();
-    return Uint8List.fromList(output.bytes);
   }
 
   /// Converts [AssetEntity]s that were successfully hashed to [Asset]s

mobile/pubspec.lock

@@ -282,7 +282,7 @@ packages:
     source: hosted
     version: "0.3.3+4"
   crypto:
-    dependency: "direct main"
+    dependency: transitive
     description:
       name: crypto
       sha256: ff625774173754681d66daaf4a448684fb04b78f902da9cb3d308c19cc5e8bab

mobile/pubspec.yaml

@@ -54,7 +54,6 @@ dependencies:
   permission_handler: ^10.2.0
   device_info_plus: ^8.1.0
   connectivity_plus: ^4.0.1
-  crypto: ^3.0.3 # TODO remove once native crypto is used on iOS
   wakelock_plus: ^1.1.1
   flutter_local_notifications: ^15.1.0+1
   timezone: ^0.9.2