EncryptHelper.py

import base64
import hashlib
import json
import struct
import time

from Crypto.Cipher import AES
from Crypto.Util.Padding import pad


class EncryptHelper:
    words = [1735160886, 1748382068, 1631021929, 1936684855]
    key_bytes = b''.join(struct.pack('>I', word) for word in words)
    iv = b'4hrivgw5s342f9b2'

    @staticmethod
    def get_md5(url: str) -> str:
        """
        根据传入的url和params生成MD5摘要

        :param url: API的url
        :return: MD5摘要
        """
        md5_hash = hashlib.md5(('url=' + url).encode('utf-8')).hexdigest()
        return md5_hash

    @staticmethod
    def encrypt_text(text: str) -> str:
        """
        根据传入的text生成AES加密后的内容，并将其转为base64编码

        :param text: 需要加密的字符串
        :return: 加密后的base64编码字符串
        """
        text_encoded = base64.b64encode(text.encode())

        cipher = AES.new(EncryptHelper.key_bytes, AES.MODE_CBC, EncryptHelper.iv)
        ciphertext = cipher.encrypt(pad(text_encoded, AES.block_size))
        ciphertext_base64 = base64.b64encode(ciphertext).decode()

        return ciphertext_base64

    @staticmethod
    def base64_to_hex(encoded_data):
        """
        把加密后的payload转为16进制

        :param encoded_data: 加密后的payload
        :return:
        """
        decoded_data = base64.b64decode(encoded_data)
        hex_string = ''.join([format(byte, '02x') for byte in decoded_data])
        return hex_string

    @staticmethod
    def encrypt_payload(payload: str) -> str:
        """
        把小红书加密参数payload转16进制 再使用base64编码

        :param payload: 要加密处理的payload内容
        :return: 加密后并进行base64编码的字符串
        """
        obj = {
            "signSvn": "55",
            "signType": "x2",
            "appID": "xhs-pc-web",
            "signVersion": "1",
            "payload": EncryptHelper.base64_to_hex(payload)
        }
        return base64.b64encode(json.dumps(obj, separators=(',', ':')).encode()).decode()

    @staticmethod
    def encrypt_xs(url: str, a1: str, ts: str) -> str:
        """
        将传入的参数加密为小红书的xs

        :param url: API请求的URL
        :param a1: 签名参数a1
        :param ts: 时间戳
        :return: 最终的加密签名字符串，前缀为“XYW_”
        """
        text = (f'x1={EncryptHelper.get_md5(url)};'
                f'x2=0|0|0|1|0|0|1|0|0|0|1|0|0|0|0|1|0|0|0;'
                f'x3={a1};'
                f'x4={ts};')
        return 'XYW_' + EncryptHelper.encrypt_payload(EncryptHelper.encrypt_text(text))