Implement chat server auth, models, handlers, and docs context

lib/src/auth/crypto_service.dart

@@ -1,13 +1,13 @@
 import 'dart:convert';
+import 'dart:math';
 import 'dart:typed_data';
 
 import 'package:bcrypt/bcrypt.dart';
-import 'package:collection/collection.dart';
 import 'package:crypto/crypto.dart';
-import 'package:crypton/crypton.dart';
-import 'package:dart_jsonwebtoken/dart_jsonwebtoken.dart';
+import 'package:crypton/crypton.dart' as crypton;
+import 'package:dart_jsonwebtoken/dart_jsonwebtoken.dart' as jwt;
 
-import '../config/config.dart';
+import '../../config/config.dart';
 
 class KeyPair {
   final String publicKey;
@@ -31,7 +31,7 @@ class KeyPair {
 class CryptoService {
   /// Generate a new Ed25519 key pair
   static KeyPair generateKeyPair() {
-    final keyPair = ECKeypair.fromRandom();
+    final keyPair = crypton.ECKeypair.fromRandom();
     return KeyPair(
       publicKey: keyPair.publicKey.toString(),
       privateKey: keyPair.privateKey.toString(),
@@ -40,17 +40,19 @@ class CryptoService {
 
   /// Sign data with private key
   static String sign(String data, String privateKey) {
-    final privKey = ECPrivateKey.fromString(privateKey);
-    final signature = privKey.createSignature(data);
-    return signature.toString();
+    final privKey = crypton.ECPrivateKey.fromString(privateKey);
+    final message = Uint8List.fromList(utf8.encode(data));
+    final signature = privKey.createSHA256Signature(message);
+    return base64Encode(signature);
   }
 
   /// Verify signature with public key
   static bool verify(String data, String signature, String publicKey) {
     try {
-      final pubKey = ECPublicKey.fromString(publicKey);
-      final sig = ECSignature.fromString(signature);
-      return pubKey.verifySignature(data, sig);
+      final pubKey = crypton.ECPublicKey.fromString(publicKey);
+      final message = Uint8List.fromList(utf8.encode(data));
+      final signatureBytes = Uint8List.fromList(base64Decode(signature));
+      return pubKey.verifySHA256Signature(message, signatureBytes);
     } catch (_) {
       return false;
     }
@@ -118,6 +120,8 @@ class EncryptedKey {
 }
 
 class AuthService {
+  static final _nonceRandom = Random.secure();
+
   /// Generate JWT token for user
   static String generateToken(String userId, String username) {
     final payload = {
@@ -125,9 +129,9 @@ class AuthService {
       'username': username,
     };
 
-    final jwt = JWT(payload);
-    return jwt.sign(
-      SecretKey(Config.jwtSecret),
+    final token = jwt.JWT(payload);
+    return token.sign(
+      jwt.SecretKey(Config.jwtSecret),
       expiresIn: Config.tokenExpiry,
     );
   }
@@ -135,8 +139,8 @@ class AuthService {
   /// Verify JWT token and return payload
   static Map<String, dynamic>? verifyToken(String token) {
     try {
-      final jwt = JWT.verify(token, SecretKey(Config.jwtSecret));
-      return Map<String, dynamic>.from(jwt.payload as Map);
+      final verified = jwt.JWT.verify(token, jwt.SecretKey(Config.jwtSecret));
+      return Map<String, dynamic>.from(verified.payload as Map);
     } catch (_) {
       return null;
     }
@@ -154,8 +158,8 @@ class AuthService {
 
   /// Generate a nonce for signature verification
   static String generateNonce() {
-    final bytes = List<int>.generate(32, (_) => DateTime.now().microsecondsSinceEpoch % 256);
-    final randomBytes = sha256.convert(bytes as Uint8List);
-    return randomBytes.toString().substring(0, 32);
+    final bytes = List<int>.generate(32, (_) => _nonceRandom.nextInt(256));
+    final hash = sha256.convert(bytes);
+    return hash.toString().substring(0, 32);
   }
 }