更新 README.md

.gitignore

@@ -0,0 +1,20 @@
+# 运行时数据（聊天记录/账户/服务器状态）
+data/
+server_data/
+ChaosCryptChat/data/
+ChaosCryptChat/server_data/
+
+# 密钥文件（严禁上传！）
+*.key
+
+# Python 缓存
+__pycache__/
+*.pyc
+
+# 媒体缓存
+media/
+
+# 系统文件
+Thumbs.db
+.DS_Store
+desktop.ini

ChaosCryptChat/server.py

@@ -0,0 +1,418 @@
+# -*- coding: utf-8 -*-
+"""
+☁️ 混沌加密聊天 - 中央服务器 (解决 NAT / 公网穿透)
+====================================================
+- 服务器只负责: 用户认证 + 群成员管理 + 消息中继
+- 所有消息内容由客户端加密, 服务器【不持有群密钥】
+- 密钥只在客户端本地, 永不上传到服务器
+- 部署: 放到有公网IP的机器, python server.py [端口]
+"""
+import os
+import sys
+import json
+import time
+import base64
+import struct
+import socket
+import hashlib
+import threading
+import sqlite3
+
+SERVER_HOST = '0.0.0.0'
+SERVER_PORT = 8666
+DB_PATH = os.path.join(os.path.dirname(os.path.abspath(__file__)), 'server_data', 'server.db')
+
+MAX_FRAME = 256 * 1024 * 1024
+
+
+# ==================== 帧协议 (与客户端一致) ====================
+def send_msg(sock, obj):
+    payload = json.dumps(obj, ensure_ascii=False).encode('utf-8')
+    sock.sendall(struct.pack('>I', len(payload)) + payload)
+
+
+def recv_exact(sock, n):
+    data = b''
+    while len(data) < n:
+        try:
+            chunk = sock.recv(n - len(data))
+        except socket.timeout:
+            continue
+        except Exception:
+            return None
+        if not chunk:
+            return None
+        data += chunk
+    return data
+
+
+def recv_msg(sock):
+    header = recv_exact(sock, 4)
+    if header is None:
+        return None
+    length = struct.unpack('>I', header)[0]
+    if length <= 0 or length > MAX_FRAME:
+        return None
+    payload = recv_exact(sock, length)
+    if payload is None:
+        return None
+    try:
+        return json.loads(payload.decode('utf-8'))
+    except Exception:
+        return None
+
+
+# ==================== 服务器数据库 ====================
+class ServerDB:
+    def __init__(self, db_path=DB_PATH):
+        os.makedirs(os.path.dirname(db_path), exist_ok=True)
+        self.conn = sqlite3.connect(db_path, check_same_thread=False)
+        self.conn.row_factory = sqlite3.Row
+        self.lock = threading.Lock()
+        self._init()
+
+    def _init(self):
+        with self.lock:
+            cur = self.conn.cursor()
+            cur.execute('''CREATE TABLE IF NOT EXISTS users(
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                username TEXT UNIQUE NOT NULL,
+                salt TEXT NOT NULL,
+                pass_hash TEXT NOT NULL,
+                created_at REAL)''')
+            cur.execute('''CREATE TABLE IF NOT EXISTS groups(
+                id TEXT PRIMARY KEY,
+                owner TEXT NOT NULL,
+                name TEXT,
+                announcement TEXT,
+                created_at REAL)''')
+            cur.execute('''CREATE TABLE IF NOT EXISTS group_members(
+                group_id TEXT NOT NULL,
+                username TEXT NOT NULL,
+                joined_at REAL,
+                PRIMARY KEY(group_id, username))''')
+            self.conn.commit()
+
+    def register(self, username, password):
+        salt = os.urandom(16).hex()
+        ph = hashlib.pbkdf2_hmac('sha256', password.encode('utf-8'),
+                                 bytes.fromhex(salt), 120000).hex()
+        try:
+            with self.lock:
+                cur = self.conn.cursor()
+                cur.execute('INSERT INTO users(username, salt, pass_hash, created_at) VALUES(?,?,?,?)',
+                            (username, salt, ph, time.time()))
+                self.conn.commit()
+            return True, 'ok'
+        except sqlite3.IntegrityError:
+            return False, '该用户名已被注册'
+
+    def login(self, username, password):
+        with self.lock:
+            cur = self.conn.cursor()
+            row = cur.execute('SELECT * FROM users WHERE username=?', (username,)).fetchone()
+        if row is None:
+            return None, '用户不存在'
+        ph = hashlib.pbkdf2_hmac('sha256', password.encode('utf-8'),
+                                 bytes.fromhex(row['salt']), 120000).hex()
+        if ph != row['pass_hash']:
+            return None, '密码错误'
+        return row, 'ok'
+
+    def create_group(self, group_id, owner, name):
+        with self.lock:
+            cur = self.conn.cursor()
+            cur.execute('INSERT INTO groups(id, owner, name, created_at) VALUES(?,?,?,?)',
+                        (group_id, owner, name, time.time()))
+            cur.execute('INSERT OR IGNORE INTO group_members(group_id, username, joined_at) VALUES(?,?,?)',
+                        (group_id, owner, time.time()))
+            self.conn.commit()
+
+    def add_member(self, group_id, username):
+        with self.lock:
+            cur = self.conn.cursor()
+            row = cur.execute('SELECT 1 FROM groups WHERE id=?', (group_id,)).fetchone()
+            if row is None:
+                return False
+            cur.execute('INSERT OR IGNORE INTO group_members(group_id, username, joined_at) VALUES(?,?,?)',
+                        (group_id, username, time.time()))
+            self.conn.commit()
+            return True
+
+    def remove_member(self, group_id, username):
+        with self.lock:
+            cur = self.conn.cursor()
+            cur.execute('DELETE FROM group_members WHERE group_id=? AND username=?',
+                        (group_id, username))
+            self.conn.commit()
+
+    def get_group(self, group_id):
+        with self.lock:
+            cur = self.conn.cursor()
+            return cur.execute('SELECT id, name, announcement, owner FROM groups WHERE id=?',
+                               (group_id,)).fetchone()
+
+    def list_groups(self, username):
+        with self.lock:
+            cur = self.conn.cursor()
+            rows = cur.execute('''SELECT g.id, g.name, g.owner, g.announcement FROM groups g
+                                  JOIN group_members m ON m.group_id = g.id
+                                  WHERE m.username=?''', (username,)).fetchall()
+        return [{'id': r['id'], 'name': r['name'], 'owner': r['owner'],
+                 'announcement': r['announcement'] or ''} for r in rows]
+
+    def is_owner(self, group_id, username):
+        with self.lock:
+            cur = self.conn.cursor()
+            row = cur.execute('SELECT owner FROM groups WHERE id=?', (group_id,)).fetchone()
+        return bool(row and row['owner'] == username)
+
+    def set_group_name(self, group_id, name):
+        with self.lock:
+            cur = self.conn.cursor()
+            cur.execute('UPDATE groups SET name=? WHERE id=?', (name, group_id))
+            self.conn.commit()
+
+    def set_announcement(self, group_id, text):
+        with self.lock:
+            cur = self.conn.cursor()
+            cur.execute('UPDATE groups SET announcement=? WHERE id=?', (text, group_id))
+            self.conn.commit()
+
+    def members(self, group_id):
+        with self.lock:
+            cur = self.conn.cursor()
+            rows = cur.execute('SELECT username FROM group_members WHERE group_id=?',
+                               (group_id,)).fetchall()
+        return [r['username'] for r in rows]
+
+
+# ==================== 中央服务器 ====================
+class CentralServer:
+    def __init__(self, host=SERVER_HOST, port=SERVER_PORT, db=None):
+        self.host = host
+        self.port = port
+        self.db = db or ServerDB()
+        self.sock = None
+        self.running = False
+        self.clients = {}      # cid -> {socket, username, token, addr, lock}
+        self.next_id = 1
+        self.lock = threading.Lock()
+
+    def start(self):
+        self.sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
+        self.sock.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1)
+        self.sock.bind((self.host, self.port))
+        self.sock.listen(50)
+        self.running = True
+        print(f"☁️ 中央服务器启动: {self.host}:{self.port}")
+        print(f"   数据库: {DB_PATH}")
+        threading.Thread(target=self._accept_loop, daemon=True).start()
+
+    def stop(self):
+        self.running = False
+        if self.sock:
+            try:
+                self.sock.close()
+            except Exception:
+                pass
+            self.sock = None
+        with self.lock:
+            socks = [c['socket'] for c in self.clients.values()]
+            self.clients.clear()
+        for s in socks:
+            try:
+                s.close()
+            except Exception:
+                pass
+
+    def _accept_loop(self):
+        while self.running:
+            try:
+                client, addr = self.sock.accept()
+                with self.lock:
+                    cid = self.next_id
+                    self.next_id += 1
+                    self.clients[cid] = {'socket': client, 'username': None,
+                                         'token': None, 'addr': addr,
+                                         'lock': threading.Lock()}
+                print(f"  📶 新连接: {addr[0]}:{addr[1]}")
+                threading.Thread(target=self._handler, args=(cid,), daemon=True).start()
+            except Exception:
+                break
+
+    def _send(self, cid, msg):
+        with self.lock:
+            c = self.clients.get(cid)
+        if c:
+            try:
+                with c['lock']:
+                    send_msg(c['socket'], msg)
+            except Exception:
+                pass
+
+    def _handler(self, cid):
+        client = self.clients[cid]['socket']
+        # 第一步: 认证 (register 自动登录 或 login)
+        try:
+            msg = recv_msg(client)
+            if msg and msg.get('type') == 'register':
+                username = str(msg.get('username', ''))[:24]
+                password = str(msg.get('password', ''))
+                ok, err = self.db.register(username, password)
+                if not ok:
+                    self._send(cid, {'type': 'error', 'msg': err})
+                    self._remove(cid)
+                    return
+                row, _ = self.db.login(username, password)
+                self._auth_ok(cid, row)
+            elif msg and msg.get('type') == 'login':
+                username = str(msg.get('username', ''))[:24]
+                password = str(msg.get('password', ''))
+                row, err = self.db.login(username, password)
+                if row is None:
+                    self._send(cid, {'type': 'error', 'msg': err})
+                    self._remove(cid)
+                    return
+                self._auth_ok(cid, row)
+            else:
+                self._remove(cid)
+                return
+        except Exception:
+            self._remove(cid)
+            return
+
+        # 第二步: 业务消息循环
+        while self.running:
+            if cid not in self.clients:
+                break
+            try:
+                msg = recv_msg(client)
+                if msg is None:
+                    break
+                self._handle(cid, msg)
+            except Exception:
+                break
+        self._remove(cid)
+
+    def _auth_ok(self, cid, row):
+        username = row['username']
+        token = os.urandom(16).hex()
+        with self.lock:
+            if cid in self.clients:
+                self.clients[cid]['username'] = username
+                self.clients[cid]['token'] = token
+        print(f"  👤 {username} 已登录")
+        self._send(cid, {'type': 'login_ok', 'token': token, 'username': username})
+
+    def _handle(self, cid, msg):
+        with self.lock:
+            if cid not in self.clients:
+                return
+            username = self.clients[cid]['username']
+        mtype = msg.get('type')
+
+        if mtype == 'create_group':
+            group_id = str(msg.get('group_id') or f"g{int(time.time()*1000)}-{os.urandom(3).hex()}")
+            name = str(msg.get('name', ''))[:40]
+            self.db.create_group(group_id, username, name or group_id)
+            print(f"  📡 {username} 创建群 [{name}] ({group_id})")
+            self._send(cid, {'type': 'group_created', 'group_id': group_id, 'name': name})
+
+        elif mtype == 'list_groups':
+            groups = self.db.list_groups(username)
+            self._send(cid, {'type': 'groups', 'groups': groups})
+
+        elif mtype == 'join_group':
+            group_id = str(msg.get('group_id', ''))
+            if self.db.add_member(group_id, username):
+                self._send(cid, {'type': 'join_ok', 'group_id': group_id})
+                # 推送当前群名/公告给新成员
+                ginfo = self.db.get_group(group_id)
+                self._send(cid, {'type': 'group_info', 'group_id': group_id,
+                                 'name': ginfo['name'] if ginfo else '',
+                                 'announcement': ginfo['announcement'] if ginfo else ''})
+                self._broadcast_group(group_id,
+                                      {'type': 'system', 'text': f"👋 {username} 加入了群",
+                                       'group_id': group_id}, exclude=cid)
+            else:
+                self._send(cid, {'type': 'error', 'msg': '群不存在'})
+
+        elif mtype == 'set_group_name':
+            group_id = str(msg.get('group_id', ''))
+            name = str(msg.get('name', ''))[:40]
+            if self.db.is_owner(group_id, username):
+                self.db.set_group_name(group_id, name)
+                self._broadcast_group(group_id, {'type': 'group_name', 'group_id': group_id,
+                                                 'name': name}, exclude=None)
+                print(f"  🏷️ {username} 修改群名: {name}")
+            else:
+                self._send(cid, {'type': 'error', 'msg': '仅群主可修改群名'})
+
+        elif mtype == 'set_announcement':
+            group_id = str(msg.get('group_id', ''))
+            text = str(msg.get('text', ''))[:500]
+            if self.db.is_owner(group_id, username):
+                self.db.set_announcement(group_id, text)
+                self._broadcast_group(group_id, {'type': 'announcement', 'group_id': group_id,
+                                                 'text': text}, exclude=None)
+                print(f"  📢 {username} 设置公告: {text[:30]}")
+            else:
+                self._send(cid, {'type': 'error', 'msg': '仅群主可设置公告'})
+
+        elif mtype == 'leave_group':
+            group_id = str(msg.get('group_id', ''))
+            self.db.remove_member(group_id, username)
+            self._send(cid, {'type': 'leave_ok', 'group_id': group_id})
+            self._broadcast_group(group_id,
+                                  {'type': 'system', 'text': f"👋 {username} 离开了群",
+                       'group_id': group_id}, exclude=cid)
+
+        elif mtype == 'group_members':
+            group_id = str(msg.get('group_id', ''))
+            self._send(cid, {'type': 'members', 'group_id': group_id,
+                             'members': self.db.members(group_id)})
+
+        elif mtype == 'group_message':
+            group_id = str(msg.get('group_id', ''))
+            payload = msg.get('payload')
+            # 转发给同群其他成员 (服务器不解析加密内容)
+            self._broadcast_group(group_id,
+                                  {'type': 'group_message', 'group_id': group_id,
+                                   'from': username, 'payload': payload}, exclude=cid)
+
+    def _broadcast_group(self, group_id, msg, exclude=None):
+        members = set(self.db.members(group_id))
+        with self.lock:
+            targets = [(cid2, c['socket'], c['lock']) for cid2, c in self.clients.items()
+                       if c.get('username') in members and cid2 != exclude]
+        for cid2, sock, lk in targets:
+            try:
+                with lk:
+                    send_msg(sock, msg)
+            except Exception:
+                pass
+
+    def _remove(self, cid):
+        with self.lock:
+            entry = self.clients.pop(cid, None)
+        if entry:
+            try:
+                entry['socket'].close()
+            except Exception:
+                pass
+            if entry['username']:
+                print(f"  🔌 {entry['username']} 断开")
+
+
+if __name__ == '__main__':
+    port = int(sys.argv[1]) if len(sys.argv) > 1 else SERVER_PORT
+    srv = CentralServer(port=port)
+    srv.start()
+    print("按 Ctrl+C 停止服务器")
+    try:
+        while True:
+            time.sleep(1)
+    except KeyboardInterrupt:
+        srv.stop()
+        print("\n☁️ 服务器已停止")

SECURITY.md

@@ -765,4 +765,71 @@ DeriveKey(K\_user, K\_short, n) 包含：
 ================================================================================
 
 
+================================================================================
+十、ChaosCryptChat 聊天模块安全分析（v2.0）
+================================================================================
+
+本部分分析 ChaosCryptChat（端到端加密聊天系统）的安全模型。
+
+10.1 威胁模型
+
+    假设：
+        - 中央服务器可被攻击者完全控制（最坏情况）
+        - 网络传输可被监听、篡改、重放
+        - 客户端本地文件可信（不讨论端侧木马）
+
+10.2 端到端加密
+
+    消息路径：
+        明文 → 混沌加密（群密钥 + nonce 派生消息密钥）→ 密文 → 网络 → 密文 → 混沌解密 → 明文
+
+    关键属性：
+        - 群密钥只存在于客户端本地，永不上传服务器
+        - 服务器仅中继密文，无法解密任何消息
+        - 每条消息使用独立 nonce 派生消息密钥，避免重放
+        - HMAC-SHA256 完整性校验：密文被篡改将导致解密失败
+
+10.3 中央服务器模型
+
+    服务器职责：用户认证 + 群成员管理 + 消息中继
+
+    服务器不持有：
+        - 群密钥（session key）
+        - 消息明文
+        - 每用户密钥（user key，经服务器持有密钥加密后下发）
+
+    服务器被攻陷的影响：
+        - 无法解密历史或实时聊天内容
+        - 可能泄露：用户名、登录时间、中继日志、群成员关系
+        - 可实施：拒绝服务、成员关系观察（元数据泄露）
+
+10.4 身份认证
+
+    用户密码：PBKDF2-HMAC-SHA256，120,000 次迭代 + 随机盐
+    每用户密钥：加入群时签发，用于 HMAC 签名，防止成员冒充他人
+    群密钥认证：加入群需提供群密钥派生的认证凭据，证明是群成员
+
+10.5 消息完整性
+
+    文本/语音/文件消息均携带 HMAC：
+        - 文本: HMAC(密文 + 群密钥)
+        - 二进制: HMAC('BIN|' + 群密钥 + nonce + 密文)
+    
+    篡改检测：接收方重算 HMAC 不匹配 → 拒绝消息
+
+10.6 已知限制
+
+    1. 端到端（P2P）模式下，群主主机既是聊天者又是服务器，若群主被攻陷则群聊失守
+    2. 服务器虽无法解密内容，但能观察到元数据（谁和谁在何时通信）
+    3. 群密钥通过群主手动分享，存在被截获的风险（需可信渠道传递）
+    4. 语音播放/录音依赖第三方库（pygame/sounddevice），其安全性不在本系统保证范围
+    5. 消息撤回仅做本地标记 + 服务器广播，已离线成员仍可能看到撤回前的消息
+
+10.7 结论
+
+    ChaosCryptChat 提供端到端加密 + 完整性校验 + 身份认证，服务器无法解密内容。
+    其安全边界符合"服务器不可信"模型，适合对隐私有要求但不涉及合规认证的通信场景。
+    元数据泄露与密钥分享渠道仍需用户自行权衡与管理。
+
+================================================================================