import base64 import json from Crypto.Cipher import AES class WXBizDataCrypt: def __init__(self, appId, sessionKey): self.appId = appId self.sessionKey = sessionKey def decrypt(self, encryptedData, iv): # base64 decode sessionKey = base64.b64decode(self.sessionKey) encryptedData = base64.b64decode(encryptedData) iv = base64.b64decode(iv) cipher = AES.new(sessionKey, AES.MODE_CBC, iv) decrypted = json.loads(self._unpad(cipher.decrypt(encryptedData))) if decrypted['watermark']['appid'] != self.appId: raise Exception('Invalid Buffer') return decrypted def _unpad(self, s): return s[:-ord(s[len(s)-1:])]