Import AITURK IDE 1.0.0-beta.1 from Hermes 63279301; preserve MIT license

plugins/platforms/wecom/__init__.py

@@ -0,0 +1,3 @@
+from .adapter import register
+
+__all__ = ["register"]

plugins/platforms/wecom/callback_adapter.py

@@ -0,0 +1,484 @@
+"""WeCom callback-mode adapter for self-built enterprise applications.
+
+Unlike the bot/websocket adapter in ``wecom.py``, this handles the standard
+WeCom callback flow: WeCom POSTs encrypted XML to an HTTP endpoint, the
+adapter decrypts it, queues the message for the agent, and immediately
+acknowledges.  The agent's reply is delivered later via the proactive
+``message/send`` API using an access-token.
+
+Supports multiple self-built apps under one gateway instance, scoped by
+``corp_id:user_id`` to avoid cross-corp collisions.
+"""
+
+from __future__ import annotations
+
+import asyncio
+import logging
+import socket as _socket
+import time
+from typing import Any, Dict, List, Optional
+# Security: parse untrusted, pre-auth request bodies (WeCom callbacks) with
+# defusedxml to block billion-laughs / entity-expansion (and XXE) DoS. The
+# parsing API (fromstring) is a drop-in for the stdlib calls used below;
+# response-building XML lives in wecom_crypto.py and is not parsed here.
+try:
+    import defusedxml.ElementTree as ET
+
+    DEFUSEDXML_AVAILABLE = True
+except ImportError:
+    ET = None  # type: ignore[assignment]
+    DEFUSEDXML_AVAILABLE = False
+
+try:
+    from aiohttp import web
+
+    AIOHTTP_AVAILABLE = True
+except ImportError:
+    web = None  # type: ignore[assignment]
+    AIOHTTP_AVAILABLE = False
+
+try:
+    import httpx
+
+    HTTPX_AVAILABLE = True
+except ImportError:
+    httpx = None  # type: ignore[assignment]
+    HTTPX_AVAILABLE = False
+
+from gateway.config import Platform, PlatformConfig
+from gateway.platforms.base import BasePlatformAdapter, MessageEvent, MessageType, SendResult
+from plugins.platforms.wecom.wecom_crypto import WXBizMsgCrypt, WeComCryptoError
+
+logger = logging.getLogger(__name__)
+
+# ``None`` → aiohttp/asyncio ``create_server`` binds one listening socket per
+# address family (IPv4 + IPv6). The old "0.0.0.0" default bound IPv4 ONLY and
+# was unreachable over IPv6-only private networks (e.g. Fly.io 6PN) — same
+# bug as the LINE adapter (NS-603) and gateway/platforms/webhook.py
+# (d542894ad). Pin a host via WECOM_CALLBACK_HOST or extra.host.
+DEFAULT_HOST = None
+DEFAULT_PORT = 8645
+DEFAULT_PATH = "/wecom/callback"
+# Cap pre-auth request bodies. WeCom callbacks are small encrypted XML
+# envelopes (media is delivered out-of-band via MediaId, never inline), so
+# 64 KB is ample for any legitimate message while bounding the work an
+# unauthenticated POST can force before signature verification.
+_MAX_BODY = 65_536
+ACCESS_TOKEN_TTL_SECONDS = 7200
+MESSAGE_DEDUP_TTL_SECONDS = 300
+
+
+def check_wecom_callback_requirements() -> bool:
+    """PASSIVE probe: are aiohttp/httpx/defusedxml importable right now?
+
+    Registry ``check_fn`` — must never install anything.  The ACTIVE
+    lazy-installer is ``ensure_wecom_callback_requirements`` below.
+    """
+    return AIOHTTP_AVAILABLE and HTTPX_AVAILABLE and DEFUSEDXML_AVAILABLE
+
+
+def ensure_wecom_callback_requirements() -> bool:
+    """ACTIVE lazy-installer for the ``platform.wecom_callback`` feature.
+
+    Registered as ``ensure_deps_fn``: the registry's ``create_adapter()``
+    runs it when the passive probe fails, right before the gateway connects
+    the platform (#79812).  Installs ``defusedxml`` (the only non-core dep;
+    aiohttp/httpx ship with every messaging install) and rebinds the module
+    globals.  Before this hook existed, the passive ``check_fn`` returned
+    False forever on installs without the ``wecom`` extra and the
+    ``platform.wecom_callback`` LAZY_DEPS entry was never exercised.
+    """
+    if check_wecom_callback_requirements():
+        return True
+
+    def _import() -> dict:
+        import defusedxml.ElementTree as _ET
+
+        return {"ET": _ET, "DEFUSEDXML_AVAILABLE": True}
+
+    try:
+        from tools.lazy_deps import ensure_and_bind
+    except Exception:  # pragma: no cover — defensive
+        return False
+    if not ensure_and_bind("platform.wecom_callback", _import, globals(), prompt=False):
+        return False
+    return check_wecom_callback_requirements()
+
+
+class WecomCallbackAdapter(BasePlatformAdapter):
+    def __init__(self, config: PlatformConfig):
+        super().__init__(config, Platform.WECOM_CALLBACK)
+        extra = config.extra or {}
+        # Falsy host (None/"") collapses to the dual-stack default.
+        _raw_host = extra.get("host") or DEFAULT_HOST
+        self._host = str(_raw_host) if _raw_host else None
+        self._port = int(extra.get("port") or DEFAULT_PORT)
+        self._path = str(extra.get("path") or DEFAULT_PATH)
+        self._apps: List[Dict[str, Any]] = self._normalize_apps(extra)
+        self._runner: Optional[web.AppRunner] = None
+        self._site: Optional[web.TCPSite] = None
+        self._app: Optional[web.Application] = None
+        self._http_client: Optional[httpx.AsyncClient] = None
+        self._message_queue: asyncio.Queue[MessageEvent] = asyncio.Queue()
+        self._poll_task: Optional[asyncio.Task] = None
+        self._seen_messages: Dict[str, float] = {}
+        self._user_app_map: Dict[str, str] = {}
+        self._access_tokens: Dict[str, Dict[str, Any]] = {}
+
+    # ------------------------------------------------------------------
+    # App normalisation
+    # ------------------------------------------------------------------
+
+    @staticmethod
+    def _user_app_key(corp_id: str, user_id: str) -> str:
+        return f"{corp_id}:{user_id}" if corp_id else user_id
+
+    @staticmethod
+    def _normalize_apps(extra: Dict[str, Any]) -> List[Dict[str, Any]]:
+        apps = extra.get("apps")
+        if isinstance(apps, list) and apps:
+            return [dict(app) for app in apps if isinstance(app, dict)]
+        if extra.get("corp_id"):
+            return [
+                {
+                    "name": extra.get("name") or "default",
+                    "corp_id": extra.get("corp_id", ""),
+                    "corp_secret": extra.get("corp_secret", ""),
+                    "agent_id": str(extra.get("agent_id", "")),
+                    "token": extra.get("token", ""),
+                    "encoding_aes_key": extra.get("encoding_aes_key", ""),
+                }
+            ]
+        return []
+
+    # ------------------------------------------------------------------
+    # Lifecycle
+    # ------------------------------------------------------------------
+
+    async def connect(self, *, is_reconnect: bool = False) -> bool:
+        # ``is_reconnect`` is forwarded by GatewayRunner on every retry per
+        # the BasePlatformAdapter.connect contract. Callback adapters have
+        # no server-side queue to preserve, so the flag is accepted-and-
+        # ignored — but the kwarg MUST be present or the reconnect watcher
+        # dies with TypeError and the platform silently stays offline.
+        del is_reconnect
+        if not self._apps:
+            logger.warning("[WecomCallback] No callback apps configured")
+            return False
+        if not check_wecom_callback_requirements():
+            logger.warning("[WecomCallback] aiohttp/httpx not installed")
+            return False
+
+        # Quick port-in-use check.
+        try:
+            with _socket.socket(_socket.AF_INET, _socket.SOCK_STREAM) as sock:
+                sock.settimeout(1)
+                sock.connect(("127.0.0.1", self._port))
+            logger.error("[WecomCallback] Port %d already in use", self._port)
+            return False
+        except (ConnectionRefusedError, OSError):
+            pass
+
+        try:
+            # Tighter keepalive so idle CLOSE_WAIT drains promptly (#18451).
+            from gateway.platforms._http_client_limits import platform_httpx_limits
+            self._http_client = httpx.AsyncClient(timeout=20.0, limits=platform_httpx_limits())
+            # client_max_size rejects oversized bodies at the aiohttp layer
+            # (413) before our handler — and before any signature work — runs.
+            self._app = web.Application(client_max_size=_MAX_BODY)
+            self._app.router.add_get("/health", self._handle_health)
+            self._app.router.add_get(self._path, self._handle_verify)
+            self._app.router.add_post(self._path, self._handle_callback)
+            self._runner = web.AppRunner(self._app)
+            await self._runner.setup()
+            self._site = web.TCPSite(self._runner, self._host, self._port)
+            await self._site.start()
+            self._poll_task = asyncio.create_task(self._poll_loop())
+            self._mark_connected()
+            logger.info(
+                "[WecomCallback] HTTP server listening on %s:%s%s",
+                self._host, self._port, self._path,
+            )
+            for app in self._apps:
+                try:
+                    await self._refresh_access_token(app)
+                except Exception as exc:
+                    logger.warning(
+                        "[WecomCallback] Initial token refresh failed for app '%s': %s",
+                        app.get("name", "default"), exc,
+                    )
+            return True
+        except Exception:
+            await self._cleanup()
+            logger.exception("[WecomCallback] Failed to start")
+            return False
+
+    async def disconnect(self) -> None:
+        self._running = False
+        if self._poll_task:
+            self._poll_task.cancel()
+            try:
+                await self._poll_task
+            except asyncio.CancelledError:
+                pass
+            self._poll_task = None
+        await self._cleanup()
+        self._mark_disconnected()
+        logger.info("[WecomCallback] Disconnected")
+
+    async def _cleanup(self) -> None:
+        self._site = None
+        if self._runner:
+            await self._runner.cleanup()
+            self._runner = None
+        self._app = None
+        if self._http_client:
+            await self._http_client.aclose()
+            self._http_client = None
+
+    # ------------------------------------------------------------------
+    # Outbound: proactive send via access-token API
+    # ------------------------------------------------------------------
+
+    async def send(
+        self,
+        chat_id: str,
+        content: str,
+        reply_to: Optional[str] = None,
+        metadata: Optional[Dict[str, Any]] = None,
+    ) -> SendResult:
+        app = self._resolve_app_for_chat(chat_id)
+        touser = chat_id.split(":", 1)[1] if ":" in chat_id else chat_id
+        try:
+            payload = {
+                "touser": touser,
+                "msgtype": "text",
+                "agentid": int(str(app.get("agent_id") or 0)),
+                "text": {"content": content[:2048]},
+                "safe": 0,
+            }
+            for _attempt in range(2):
+                token = await self._get_access_token(app)
+                resp = await self._http_client.post(
+                    f"https://qyapi.weixin.qq.com/cgi-bin/message/send?access_token={token}",
+                    json=payload,
+                )
+                data = resp.json()
+                errcode = data.get("errcode")
+                if errcode in {40001, 42001} and _attempt == 0:
+                    # WeCom rejected the token — evict the cached entry so
+                    # the next _get_access_token call forces a fresh fetch.
+                    logger.warning(
+                        "[WecomCallback] Token rejected for app '%s' (errcode=%s), refreshing",
+                        app.get("name", "default"), errcode,
+                    )
+                    self._access_tokens.pop(app["name"], None)
+                    continue
+                if errcode != 0:
+                    return SendResult(success=False, error=str(data))
+                return SendResult(
+                    success=True,
+                    message_id=str(data.get("msgid", "")),
+                    raw_response=data,
+                )
+            return SendResult(success=False, error="send failed after token refresh")
+        except Exception as exc:
+            return SendResult(success=False, error=str(exc))
+
+    def _resolve_app_for_chat(self, chat_id: str) -> Dict[str, Any]:
+        """Pick the app associated with *chat_id*, falling back sensibly."""
+        app_name = self._user_app_map.get(chat_id)
+        if not app_name and ":" not in chat_id:
+            # Legacy bare user_id — try to find a unique match.
+            matching = [k for k in self._user_app_map if k.endswith(f":{chat_id}")]
+            if len(matching) == 1:
+                app_name = self._user_app_map.get(matching[0])
+        app = self._get_app_by_name(app_name) if app_name else None
+        return app or self._apps[0]
+
+    async def get_chat_info(self, chat_id: str) -> Dict[str, Any]:
+        return {"name": chat_id, "type": "dm"}
+
+    # ------------------------------------------------------------------
+    # Inbound: HTTP callback handlers
+    # ------------------------------------------------------------------
+
+    async def _handle_health(self, request: web.Request) -> web.Response:
+        return web.json_response({"status": "ok", "platform": "wecom_callback"})
+
+    async def _handle_verify(self, request: web.Request) -> web.Response:
+        """GET endpoint — WeCom URL verification handshake."""
+        msg_signature = request.query.get("msg_signature", "")
+        timestamp = request.query.get("timestamp", "")
+        nonce = request.query.get("nonce", "")
+        echostr = request.query.get("echostr", "")
+        for app in self._apps:
+            try:
+                crypt = self._crypt_for_app(app)
+                plain = crypt.verify_url(msg_signature, timestamp, nonce, echostr)
+                return web.Response(text=plain, content_type="text/plain")
+            except Exception:
+                continue
+        return web.Response(status=403, text="signature verification failed")
+
+    async def _handle_callback(self, request: web.Request) -> web.Response:
+        """POST endpoint — receive an encrypted message callback."""
+        msg_signature = request.query.get("msg_signature", "")
+        timestamp = request.query.get("timestamp", "")
+        nonce = request.query.get("nonce", "")
+        # Explicit guard in addition to client_max_size: rejects oversized
+        # payloads before any XML parse / signature check (DoS, zip bombs).
+        body_bytes = await request.read()
+        if len(body_bytes) > _MAX_BODY:
+            logger.warning("[WecomCallback] Payload too large (%d bytes) — rejected", len(body_bytes))
+            return web.Response(status=413, text="payload too large")
+        body = body_bytes.decode("utf-8", errors="replace")
+
+        for app in self._apps:
+            try:
+                decrypted = self._decrypt_request(
+                    app, body, msg_signature, timestamp, nonce,
+                )
+                event = self._build_event(app, decrypted)
+                if event is not None:
+                    # Deduplicate: WeCom retries callbacks on timeout,
+                    # producing duplicate inbound messages (#10305).
+                    if event.message_id:
+                        now = time.time()
+                        if event.message_id in self._seen_messages:
+                            if now - self._seen_messages[event.message_id] < MESSAGE_DEDUP_TTL_SECONDS:
+                                logger.debug("[WecomCallback] Duplicate MsgId %s, skipping", event.message_id)
+                                return web.Response(text="success", content_type="text/plain")
+                            del self._seen_messages[event.message_id]
+                        self._seen_messages[event.message_id] = now
+                        # Prune expired entries when cache grows large
+                        if len(self._seen_messages) > 2000:
+                            cutoff = now - MESSAGE_DEDUP_TTL_SECONDS
+                            self._seen_messages = {k: v for k, v in self._seen_messages.items() if v > cutoff}
+                    # Record which app this user belongs to.
+                    if event.source and event.source.user_id:
+                        map_key = self._user_app_key(
+                            str(app.get("corp_id") or ""), event.source.user_id,
+                        )
+                        self._user_app_map[map_key] = app["name"]
+                    await self._message_queue.put(event)
+                # Immediately acknowledge — the agent's reply will arrive
+                # later via the proactive message/send API.
+                return web.Response(text="success", content_type="text/plain")
+            except WeComCryptoError:
+                continue
+            except Exception:
+                logger.exception("[WecomCallback] Error handling message")
+                break
+        return web.Response(status=400, text="invalid callback payload")
+
+    async def _poll_loop(self) -> None:
+        """Drain the message queue and dispatch to the gateway runner."""
+        while True:
+            event = await self._message_queue.get()
+            try:
+                task = asyncio.create_task(self.handle_message(event))
+                self._background_tasks.add(task)
+                task.add_done_callback(self._background_tasks.discard)
+            except Exception:
+                logger.exception("[WecomCallback] Failed to enqueue event")
+
+    # ------------------------------------------------------------------
+    # XML / crypto helpers
+    # ------------------------------------------------------------------
+
+    def _decrypt_request(
+        self, app: Dict[str, Any], body: str,
+        msg_signature: str, timestamp: str, nonce: str,
+    ) -> str:
+        root = ET.fromstring(body)
+        encrypt = root.findtext("Encrypt", default="")
+        crypt = self._crypt_for_app(app)
+        return crypt.decrypt(msg_signature, timestamp, nonce, encrypt).decode("utf-8")
+
+    def _build_event(self, app: Dict[str, Any], xml_text: str) -> Optional[MessageEvent]:
+        root = ET.fromstring(xml_text)
+        msg_type = (root.findtext("MsgType") or "").lower()
+        # Silently acknowledge lifecycle events.
+        if msg_type == "event":
+            event_name = (root.findtext("Event") or "").lower()
+            if event_name in {"enter_agent", "subscribe"}:
+                return None
+        if msg_type not in {"text", "event"}:
+            return None
+
+        user_id = root.findtext("FromUserName", default="")
+        corp_id = root.findtext("ToUserName", default=app.get("corp_id", ""))
+        scoped_chat_id = self._user_app_key(corp_id, user_id)
+        content = root.findtext("Content", default="").strip()
+        if not content and msg_type == "event":
+            content = "/start"
+        msg_id = (
+            root.findtext("MsgId")
+            or f"{user_id}:{root.findtext('CreateTime', default='0')}"
+        )
+        source = self.build_source(
+            chat_id=scoped_chat_id,
+            chat_name=user_id,
+            chat_type="dm",
+            user_id=user_id,
+            user_name=user_id,
+        )
+        return MessageEvent(
+            text=content,
+            message_type=MessageType.TEXT,
+            source=source,
+            raw_message=xml_text,
+            message_id=msg_id,
+        )
+
+    def _crypt_for_app(self, app: Dict[str, Any]) -> WXBizMsgCrypt:
+        return WXBizMsgCrypt(
+            token=str(app.get("token") or ""),
+            encoding_aes_key=str(app.get("encoding_aes_key") or ""),
+            receive_id=str(app.get("corp_id") or ""),
+        )
+
+    def _get_app_by_name(self, name: Optional[str]) -> Optional[Dict[str, Any]]:
+        if not name:
+            return None
+        for app in self._apps:
+            if app.get("name") == name:
+                return app
+        return None
+
+    # ------------------------------------------------------------------
+    # Access-token management
+    # ------------------------------------------------------------------
+
+    async def _get_access_token(self, app: Dict[str, Any]) -> str:
+        cached = self._access_tokens.get(app["name"])
+        now = time.time()
+        if cached and cached.get("expires_at", 0) > now + 60:
+            return cached["token"]
+        return await self._refresh_access_token(app)
+
+    async def _refresh_access_token(self, app: Dict[str, Any]) -> str:
+        resp = await self._http_client.get(
+            "https://qyapi.weixin.qq.com/cgi-bin/gettoken",
+            params={
+                "corpid": app.get("corp_id"),
+                "corpsecret": app.get("corp_secret"),
+            },
+        )
+        data = resp.json()
+        if data.get("errcode") != 0:
+            raise RuntimeError(f"WeCom token refresh failed: {data}")
+        token = data["access_token"]
+        expires_in = int(data.get("expires_in", ACCESS_TOKEN_TTL_SECONDS))
+        self._access_tokens[app["name"]] = {
+            "token": token,
+            "expires_at": time.time() + expires_in,
+        }
+        logger.info(
+            "[WecomCallback] Token refreshed for app '%s' (corp=%s), expires in %ss",
+            app.get("name", "default"),
+            app.get("corp_id", ""),
+            expires_in,
+        )
+        return token

plugins/platforms/wecom/plugin.yaml

@@ -0,0 +1,52 @@
+name: wecom-platform
+label: WeCom (Enterprise WeChat)
+kind: platform
+version: 1.0.0
+description: >
+  WeCom / Enterprise WeChat gateway adapter for Hermes Agent. Registers two
+  platforms: ``wecom`` (Smart Robot over WebSocket) and ``wecom_callback``
+  (self-built apps over an HTTP callback endpoint with AES message crypto).
+  Relays messages between WeCom chats and the Hermes agent.
+author: NousResearch
+requires_env:
+  - name: WECOM_BOT_ID
+    description: "WeCom Smart Robot bot ID"
+    prompt: "WeCom bot ID"
+    password: false
+  - name: WECOM_SECRET
+    description: "WeCom Smart Robot secret"
+    prompt: "WeCom secret"
+    password: true
+optional_env:
+  - name: WECOM_WEBSOCKET_URL
+    description: "WeCom Smart Robot WebSocket URL"
+    prompt: "WeCom WebSocket URL"
+    password: false
+  - name: WECOM_HOME_CHANNEL
+    description: "Default chat ID for cron / notification delivery"
+    prompt: "Home channel ID"
+    password: false
+  - name: WECOM_ALLOWED_USERS
+    description: "Comma-separated WeCom user IDs allowed to talk to the bot"
+    prompt: "Allowed users (comma-separated)"
+    password: false
+  - name: WECOM_CALLBACK_CORP_ID
+    description: "WeCom callback-mode corp ID (self-built apps)"
+    prompt: "WeCom callback corp ID"
+    password: false
+  - name: WECOM_CALLBACK_CORP_SECRET
+    description: "WeCom callback-mode corp secret"
+    prompt: "WeCom callback corp secret"
+    password: true
+  - name: WECOM_CALLBACK_AGENT_ID
+    description: "WeCom callback-mode agent ID"
+    prompt: "WeCom callback agent ID"
+    password: false
+  - name: WECOM_CALLBACK_TOKEN
+    description: "WeCom callback verification token"
+    prompt: "WeCom callback token"
+    password: true
+  - name: WECOM_CALLBACK_ENCODING_AES_KEY
+    description: "WeCom callback EncodingAESKey for message crypto"
+    prompt: "WeCom callback EncodingAESKey"
+    password: true

plugins/platforms/wecom/wecom_crypto.py

@@ -0,0 +1,142 @@
+"""WeCom BizMsgCrypt-compatible AES-CBC encryption for callback mode.
+
+Implements the same wire format as Tencent's official ``WXBizMsgCrypt``
+SDK so that WeCom can verify, encrypt, and decrypt callback payloads.
+"""
+
+from __future__ import annotations
+
+import base64
+import hashlib
+import os
+import secrets
+import socket
+import struct
+from typing import Optional
+from xml.etree import ElementTree as ET
+
+from cryptography.hazmat.backends import default_backend
+from cryptography.hazmat.primitives.ciphers import Cipher, algorithms, modes
+
+
+class WeComCryptoError(Exception):
+    pass
+
+
+class SignatureError(WeComCryptoError):
+    pass
+
+
+class DecryptError(WeComCryptoError):
+    pass
+
+
+class EncryptError(WeComCryptoError):
+    pass
+
+
+class PKCS7Encoder:
+    block_size = 32
+
+    @classmethod
+    def encode(cls, text: bytes) -> bytes:
+        amount_to_pad = cls.block_size - (len(text) % cls.block_size)
+        if amount_to_pad == 0:
+            amount_to_pad = cls.block_size
+        pad = bytes([amount_to_pad]) * amount_to_pad
+        return text + pad
+
+    @classmethod
+    def decode(cls, decrypted: bytes) -> bytes:
+        if not decrypted:
+            raise DecryptError("empty decrypted payload")
+        pad = decrypted[-1]
+        if pad < 1 or pad > cls.block_size:
+            raise DecryptError("invalid PKCS7 padding")
+        if decrypted[-pad:] != bytes([pad]) * pad:
+            raise DecryptError("malformed PKCS7 padding")
+        return decrypted[:-pad]
+
+
+def _sha1_signature(token: str, timestamp: str, nonce: str, encrypt: str) -> str:
+    parts = sorted([token, timestamp, nonce, encrypt])
+    return hashlib.sha1("".join(parts).encode("utf-8")).hexdigest()
+
+
+class WXBizMsgCrypt:
+    """Minimal WeCom callback crypto helper compatible with BizMsgCrypt semantics."""
+
+    def __init__(self, token: str, encoding_aes_key: str, receive_id: str):
+        if not token:
+            raise ValueError("token is required")
+        if not encoding_aes_key:
+            raise ValueError("encoding_aes_key is required")
+        if len(encoding_aes_key) != 43:
+            raise ValueError("encoding_aes_key must be 43 chars")
+        if not receive_id:
+            raise ValueError("receive_id is required")
+
+        self.token = token
+        self.receive_id = receive_id
+        self.key = base64.b64decode(encoding_aes_key + "=")
+        self.iv = self.key[:16]
+
+    def verify_url(self, msg_signature: str, timestamp: str, nonce: str, echostr: str) -> str:
+        plain = self.decrypt(msg_signature, timestamp, nonce, echostr)
+        return plain.decode("utf-8")
+
+    def decrypt(self, msg_signature: str, timestamp: str, nonce: str, encrypt: str) -> bytes:
+        expected = _sha1_signature(self.token, timestamp, nonce, encrypt)
+        if expected != msg_signature:
+            raise SignatureError("signature mismatch")
+        try:
+            cipher_text = base64.b64decode(encrypt)
+        except Exception as exc:
+            raise DecryptError(f"invalid base64 payload: {exc}") from exc
+        try:
+            cipher = Cipher(algorithms.AES(self.key), modes.CBC(self.iv), backend=default_backend())
+            decryptor = cipher.decryptor()
+            padded = decryptor.update(cipher_text) + decryptor.finalize()
+            plain = PKCS7Encoder.decode(padded)
+            content = plain[16:]  # skip 16-byte random prefix
+            xml_length = socket.ntohl(struct.unpack("I", content[:4])[0])
+            xml_content = content[4:4 + xml_length]
+            receive_id = content[4 + xml_length:].decode("utf-8")
+        except WeComCryptoError:
+            raise
+        except Exception as exc:
+            raise DecryptError(f"decrypt failed: {exc}") from exc
+
+        if receive_id != self.receive_id:
+            raise DecryptError("receive_id mismatch")
+        return xml_content
+
+    def encrypt(self, plaintext: str, nonce: Optional[str] = None, timestamp: Optional[str] = None) -> str:
+        nonce = nonce or self._random_nonce()
+        timestamp = timestamp or str(int(__import__("time").time()))
+        encrypt = self._encrypt_bytes(plaintext.encode("utf-8"))
+        signature = _sha1_signature(self.token, timestamp, nonce, encrypt)
+        root = ET.Element("xml")
+        ET.SubElement(root, "Encrypt").text = encrypt
+        ET.SubElement(root, "MsgSignature").text = signature
+        ET.SubElement(root, "TimeStamp").text = timestamp
+        ET.SubElement(root, "Nonce").text = nonce
+        return ET.tostring(root, encoding="unicode")
+
+    def _encrypt_bytes(self, raw: bytes) -> str:
+        try:
+            random_prefix = os.urandom(16)
+            msg_len = struct.pack("I", socket.htonl(len(raw)))
+            payload = random_prefix + msg_len + raw + self.receive_id.encode("utf-8")
+            padded = PKCS7Encoder.encode(payload)
+            cipher = Cipher(algorithms.AES(self.key), modes.CBC(self.iv), backend=default_backend())
+            encryptor = cipher.encryptor()
+            encrypted = encryptor.update(padded) + encryptor.finalize()
+            return base64.b64encode(encrypted).decode("utf-8")
+        except Exception as exc:
+            raise EncryptError(f"encrypt failed: {exc}") from exc
+
+    @staticmethod
+    def _random_nonce(length: int = 10) -> str:
+        alphabet = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+        return "".join(secrets.choice(alphabet) for _ in range(length))