import base64
import hashlib
import random
import socket
import struct
import time
from xml.etree import cElementTree
from Crypto.Cipher import AES
WXBizMsgCrypt_OK = 0
WXBizMsgCrypt_ValidateSignature_Error = -40001
WXBizMsgCrypt_ParseXml_Error = -40002
WXBizMsgCrypt_ComputeSignature_Error = -40003
WXBizMsgCrypt_IllegalAesKey = -40004
WXBizMsgCrypt_ValidateCorpId_Error = -40005
WXBizMsgCrypt_EncryptAES_Error = -40006
WXBizMsgCrypt_DecryptAES_Error = -40007
WXBizMsgCrypt_IllegalBuffer = -40008
WXBizMsgCrypt_EncodeBase64_Error = -40009
WXBizMsgCrypt_DecodeBase64_Error = -40010
WXBizMsgCrypt_GenReturnXml_Error = -40011
class WXBizMsgCryptException(Exception):
def __init__(self, message: str, code: int):
self.message = message
self.code = code
def __str__(self):
return f"[WXBizMsgCryptException] {self.message} ({self.code})"
def get_sha1(token: str, timestamp: str, nonce: str, encrypt: str) -> str:
"""用SHA1算法生成安全签名
:param token: 票据
:param timestamp: 时间戳
:param nonce: 密文
:param encrypt: 随机字符串
:return: 安全签名
"""
try:
sort_list = [token, timestamp, nonce, encrypt]
sort_list.sort()
sha = hashlib.sha1()
sha.update("".join(sort_list).encode())
return sha.hexdigest()
except TypeError:
raise WXBizMsgCryptException("Compute Signature Error.", WXBizMsgCrypt_ComputeSignature_Error)
class PKCS7Encoder:
"""提供基于PKCS7算法的加解密接口
"""
block_size = 32
def encode(self, text):
"""对需要加密的明文进行填充补位
:param text: 需要进行填充补位操作的明文
:return: 补齐明文字符串
"""
text_length = len(text)
# 计算需要填充的位数
amount_to_pad = self.block_size - (text_length % self.block_size)
if amount_to_pad == 0:
amount_to_pad = self.block_size
# 获得补位所用的字符
pad = chr(amount_to_pad)
return text + (pad * amount_to_pad).encode()
def decode(self, decrypted):
"""删除解密后明文的补位字符
:param decrypted: 解密后的明文
:return: 删除补位字符后的明文
"""
pad = ord(decrypted[-1])
if pad < 1 or pad > self.block_size:
pad = 0
return decrypted[:-pad]
class Crypt:
"""提供接收和推送给企业微信消息的加解密接口
"""
def __init__(self, key):
self.key = key # self.key = base64.b64decode(key+"=")
self.mode = AES.MODE_CBC # 设置加解密模式为AES的CBC模式
def encrypt(self, text: str, corp_id: str) -> str:
"""对明文进行加密
:param text: 需要加密的明文
:param corp_id:
:return: 加密得到的字符串
"""
# 16位随机字符串添加到明文开头
# 使用自定义的填充方式对明文进行补位填充
pkcs7 = PKCS7Encoder()
text = pkcs7.encode(
f'{str(random.randint(1000000000000000, 9999999999999999)).encode()}'
f'{struct.pack("I", socket.htonl(len(text)))}'
f'{text.encode()}'
f'{corp_id.encode()}'
)
# 加密
cryptor = AES.new(self.key, self.mode, self.key[:16])
try:
ciphertext = cryptor.encrypt(text)
# 使用BASE64对加密后的字符串进行编码
return base64.b64encode(ciphertext).decode('utf8')
except (TypeError, ValueError):
raise WXBizMsgCryptException('Encrypt AES Error.', WXBizMsgCrypt_EncryptAES_Error)
def decrypt(self, text: str, corp_id: str) -> str:
"""对解密后的明文进行补位删除
:param text: 密文
:param corp_id:
:return: 删除填充补位后的明文
"""
try:
cryptor = AES.new(self.key, self.mode, self.key[:16])
# 使用BASE64对密文进行解码，然后AES-CBC解密
plain_text = cryptor.decrypt(base64.b64decode(text))
except (ValueError, TypeError):
raise WXBizMsgCryptException('Decrypt AES Error.', WXBizMsgCrypt_DecryptAES_Error)
try:
pad = plain_text[-1]
# 去掉补位字符串
# pkcs7 = PKCS7Encoder()
# plain_text = pkcs7.encode(plain_text)
# 去除16位随机字符串
content = plain_text[16:-pad]
xml_len = socket.ntohl(struct.unpack("I", content[: 4])[0])
xml_content = content[4: xml_len + 4]
from_receive_id = content[xml_len + 4:]
except (ValueError, TypeError, struct.error):
raise WXBizMsgCryptException('Illegal Buffer.', WXBizMsgCrypt_IllegalBuffer)
if from_receive_id.decode('utf8') != corp_id:
raise WXBizMsgCryptException('Validate CorpId Error.', WXBizMsgCrypt_ValidateCorpId_Error)
return xml_content
class WXBizMsgCrypt:
def __init__(self, token: str, encoding_aes_key: str, corp_id: str):
"""
https://developer.work.weixin.qq.com/document/path/90238
:param token:
:param encoding_aes_key:
:param corp_id:
"""
try:
self.key = base64.b64decode(encoding_aes_key + "=")
assert len(self.key) == 32
except ValueError:
raise WXBizMsgCryptException('Illegal Aes Key.', WXBizMsgCrypt_IllegalAesKey)
self.token = token
self.corp_id = corp_id
def verify_params(self, msg_signature: str, time_stamp: str, nonce: str, echo_str: str):
"""验证参数
"""
try:
if get_sha1(self.token, time_stamp, nonce, echo_str) != msg_signature:
raise WXBizMsgCryptException('Validate Signature Error.', WXBizMsgCrypt_ValidateSignature_Error)
except TypeError:
raise WXBizMsgCryptException('Compute Signature Error.', WXBizMsgCrypt_ComputeSignature_Error)
def verify_url(self, msg_signature: str, time_stamp: str, nonce: str, echo_str: str):
"""验证URL
:param msg_signature: 签名串，对应URL参数的msg_signature
:param time_stamp: 时间戳，对应URL参数的timestamp
:param nonce: 随机串，对应URL参数的nonce
:param echo_str: 随机串，对应URL参数的echostr
:return: ret: 成功0，失败返回对应的错误码
sReplyEchoStr: 解密之后的echo_str，当return返回0时有效
"""
self.verify_params(msg_signature, time_stamp, nonce, echo_str)
return Crypt(self.key).decrypt(echo_str, self.corp_id)
def encrypt_msg(self, reply_msg: str, nonce: str, timestamp=None) -> str:
"""将企业回复用户的消息加密打包
:param reply_msg: 企业号待回复用户的消息，xml格式的字符串
:param nonce: 随机串，可以自己生成，也可以用URL参数的nonce
:param timestamp: 时间戳，可以自己生成，也可以用URL参数的timestamp,如为None则自动用当前时间
:return: sEncryptMsg: 加密后的可以直接回复用户的密文，包括msg_signature, timestamp, nonce, encrypt的xml格式的字符串
ret: 成功0，sEncryptMsg,失败返回对应的错误码None
"""
pc = Crypt(self.key)
encrypt = pc.encrypt(reply_msg, self.corp_id)
if timestamp is None:
timestamp = str(int(time.time()))
# 生成安全签名
signature = get_sha1(self.token, timestamp, nonce, encrypt)
return f"""
<xml>
<Encrypt><![CDATA[{encrypt}]]></Encrypt>
<MsgSignature><![CDATA[{signature}]]></MsgSignature>
<TimeStamp>{timestamp}</TimeStamp>
<Nonce><![CDATA[{nonce}]]></Nonce>
</xml>
"""
def decrypt_msg(self, post_data: str, msg_signature: str, timestamp: str, nonce: str):
"""检验消息的真实性，并且获取解密后的明文
:param post_data: 密文，对应POST请求的数据
:param msg_signature: 签名串，对应URL参数的msg_signature
:param timestamp: 时间戳，对应URL参数的timestamp
:param nonce: 随机串，对应URL参数的nonce
:return: 成功0，失败返回对应的错误码
xml_content: 解密后的原文，当return返回0时有效
"""
try:
xml_tree = cElementTree.fromstring(post_data)
encrypt = xml_tree.find("Encrypt").text
self.verify_params(msg_signature, timestamp, nonce, encrypt)
return Crypt(self.key).decrypt(encrypt, self.corp_id)
except cElementTree.ParseError:
raise WXBizMsgCryptException("XML Parse Error.", WXBizMsgCrypt_ParseXml_Error)