Python parses WeChat applet openid and other information

WXBizDataCrypt.py

# pip install pycryptodome
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:])]

demo.py

from WXBizDataCrypt import WXBizDataCrypt

def main():
    appId = 'wx4f4bc4dec97d474b'
    sessionKey = 'tiihtNczf5v6AKRyjwEUhQ=='
    encryptedData = 'CiyLU1Aw2KjvrjMdj8YKliAjtP4gsMZMQmRzooG2xrDcvSnxIMXFufNstNGTyaGS9uT5geRa0W4oTOb1WT7fJlAC+oNPdbB+3hVbJSRgv+4lGOETKUQz6OYStslQ142dNCuabNPGBzlooOmB231qMM85d2/fV6ChevvXvQP8Hkue1poOFtnEtpyxVLW1zAo6/1Xx1COxFvrc2d7UL/lmHInNlxuacJXwu0fjpXfz/YqYzBIBzD6WUfTIF9GRHpOn/Hz7saL8xz+W//FRAUid1OksQaQx4CMs8LOddcQhULW4ucetDf96JcR3g0gfRK4PC7E/r7Z6xNrXd2UIeorGj5Ef7b1pJAYB6Y5anaHqZ9J6nKEBvB4DnNLIVWSgARns/8wR2SiRS7MNACwTyrGvt9ts8p12PKFdlqYTopNHR1Vf7XjfhQlVsAJdNiKdYmYVoKlaRv85IfVunYzO0IKXsyl7JCUjCpoG20f0a04COwfneQAGGwd5oa+T8yO5hzuyDb/XcxxmK01EpqOyuxINew=='
    iv = 'r7BXXKkLb8qrSNn05n0qiA=='

    pc = WXBizDataCrypt(appId, sessionKey)

    print pc.decrypt(encryptedData, iv)

if __name__ == '__main__':
    main()