Hermes-agent

2026-06-14 14:30:48 -04:00
commit dac4b88b94
5058 changed files with 1884848 additions and 0 deletions
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+"""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))