Add security for score submission with key verification in flappybird

lib/flappybird/class/score.dart

@@ -1,22 +1,36 @@
 import 'package:myecl/tools/functions.dart';
 import 'package:myecl/user/class/list_users.dart';
+import 'dart:convert';
+import 'package:crypto/crypto.dart';
 
 class Score {
   late final SimpleUser user;
   late final int value;
+  late final int key;
   late final DateTime date;
   late final int position;
 
   Score({
     required this.user,
     required this.value,
+    required this.key,
     required this.date,
     required this.position,
   });
 
+  static int genKey(int value) {
+    final data = "$value";
+    final bytes = utf8.encode(data);
+    final hash = sha256.convert(bytes);
+    final hashBytes = hash.bytes;
+
+    return hashBytes.sublist(0, 4).fold(0, (acc, byte) => (acc << 8) + byte);
+  }
+
   Score.fromJson(Map<String, dynamic> json, {int? index = 0}) {
     user = SimpleUser.fromJson(json['user']);
     value = json['value'];
+    key = json['key'];
     date = processDateFromAPI(json['creation_time']);
     position = json['position'] ?? index;
   }
@@ -25,18 +39,21 @@ class Score {
     final Map<String, dynamic> data = <String, dynamic>{};
     data['user_id'] = user.id;
     data['value'] = value;
+    data['key'] = key;
     return data;
   }
 
   Score copyWith({
     SimpleUser? user,
     int? value,
+    int? key,
     DateTime? date,
     int? position,
   }) {
     return Score(
       user: user ?? this.user,
       value: value ?? this.value,
+      key: key ?? this.key,
       date: date ?? this.date,
       position: position ?? this.position,
     );
@@ -45,11 +62,12 @@ class Score {
   Score.empty() {
     user = SimpleUser.empty();
     value = 0;
+    key = genKey(0);
     date = DateTime.now();
     position = 0;
   }
 
   @override
   String toString() =>
-      'Score(user: $user, value: $value, date: $date, position: $position)';
+      'Score(user: $user, value: $value, key: $key, date: $date, position: $position)';
 }

lib/flappybird/ui/pages/game_page/game_page.dart

@@ -105,6 +105,7 @@ class GamePage extends HookConsumerWidget {
             Score(
               user: newBird.user,
               value: newBird.score,
+              key: Score.genKey(newBird.score),
               date: DateTime.now(),
               position: 0,
             ),