#!/usr/bin/env python
# encoding: utf-8

# pip install pycrypto
# 3des, cbc mode

import json
import base64
from Crypto.Cipher import DES3

def pad(text):
    """
    补齐为8的倍数
    """
    ext_byte_count = len(text) % 8
    if ext_byte_count == 0:
        return text

    add_byte_count = 8 - ext_byte_count
    return text + ' ' * add_byte_count

def tobase64(encrypt_data):
    """
    base64
    """
    return base64.b64encode(encrypt_data)

# 1. must be 16/24 bytes, 约定好
secret_key = 'a' * 24


# 2. 表单数据获取拼json, 或者其他格式, 需要和engine约定好
data = {
    'app_code': 'test',
    'auth_token': 'xxxxxxxxxx',
    'mac': '10:dd:b1:ff:fe:37:cd:90,10:dd:b1:ff:fe:37:cd:90,10:dd:b1:ff:fe:37:cd:90'
}

data_string = json.dumps(data)
data_string = pad(data_string)

print 'before encrypt: ', data_string

# 3. 加密
# use triple des
des3 = DES3.new(secret_key, mode=DES3.MODE_CBC, IV=secret_key[:8])
#  des3 = DES3.new(secret_key)
encrypt_data = des3.encrypt(data_string)

print "after encrypt:", encrypt_data

# 4. 给用户的, 再base64, 因为加密后存在很多特殊的字符

raw_base64 = tobase64(encrypt_data)
print "tobase64: ", raw_base64


# 5. 示例, 解密
# note: 反向解开不能用同一个对象
raw_data = base64.b64decode(raw_base64)
des32 = DES3.new(secret_key, mode=DES3.MODE_CBC, IV=secret_key[:8])
#  des32 = DES3.new(secret_key)
raw_base64 = des32.decrypt(raw_data)
print "after deencrypt: ", json.loads(raw_base64)