# -------------------------------
# -*- coding: utf-8 -*-
# @Author：jianghan
# @Time：2020/11/25 14:46
# @File: crypt.py
# Python版本：3.6.8
# -------------------------------


"""
1、 填充字符串和明文字符串最后一位不能相同
2、 字符串编码默认是utf-8， key和iv默认为英文字符；字符串不支持其他编码或key/iv不支持为中文字符
"""


from enum import Enum, unique
from Crypto.Cipher import AES


@unique
class Mode(Enum):
 CBC = AES.MODE_CBC
 ECB = AES.MODE_ECB


@unique
class Padding(Enum):
 """ 定义填充的字符串 """
 SPACE = ' ' # 空格


class AES256Crypto:
 def __init__(self, key, mode=Mode.ECB, padding=Padding.SPACE, iv=None):
 """
 :param key: 密钥， 32byte 长度字符串
 :param mode: 加密模式， 来源 class Mode
 :param iv: 16byte 长度字符串
 :param padding: 填充的字符串， 来源class Padding
 """
 self.padding = self.check_padding(padding)

 self.key = self.padding_key(key)
 self.iv = self.padding_iv(iv) if iv else None

 self.mode = self.check_mode(mode)

 def check_mode(self, mode):
 """ 核对 mode """
 if mode not in Mode.__members__.values():
  raise Exception(f'mode {mode} not allowed!')
 if mode == Mode.CBC and not self.iv:
  raise Exception(f'iv is required')
 return mode

 def check_padding(self, padding):
 """ 核对 padding """
 if padding not in Padding.__members__.values():
  raise Exception(f'mode {padding} not allowed!')
 return padding

 def padding_ret_byte(self, text, _len=16):
 """ 填充并转成 bytes """
 text = text.encode()
 remainder = len(text) % _len
 remainder = _len if remainder == 0 else remainder
 text += (_len - remainder) * self.padding.value.encode()
 return text

 def padding_iv(self, iv: str):
 """ 补全iv 并转成 bytes"""
 if len(iv.encode()) > 16:
  raise Exception(f'iv {iv} must <= 16bytes')
 return self.padding_ret_byte(iv)

 def padding_key(self, key: str):
 """ 补全key 并转成 bytes """
 if len(key.encode()) > 32:
  raise Exception(f'key {key} must <= 32bytes')
 return self.padding_ret_byte(key, _len=32)

 def encrypt(self, text, encode=None):
 """
 加密
 :param text: 待加密字符串
 :param encode: 传入base64里面的方法
 :return: 若encode=None则不进行base加密处理，返回bytes类型数据
 """
 text = self.padding_ret_byte(text)
 # 注意：加密中的和解密中的AES.new()不能使用同一个对象，所以在两处都使用了AES.new()
 text = AES.new(key=self.key, mode=self.mode.value, iv=self.iv).encrypt(text)
 if encode:
  return encode(text).decode()
 return text

 def decrypt(self, text, decode=None):
 """ 解密 """
 if decode:
  if type(text) == str:
  text = text.encode()
  text = decode(bytes(text))
 else:
  if type(text) != bytes:
  raise Exception(text)
 text = AES.new(key=self.key, mode=self.mode.value, iv=self.iv).decrypt(text)
 text = text.strip(self.padding.value.encode())
 return text.decode()

import json

# 这是一段待加密的字符串
text = '{"upi": "1341343", "overdue": "2020-11-26 00:00:00"}'
key = 't6LtKa3tD5X6qaJ6qOrAW3XmobFrY6ob'
iv = 'NjtP47eSECuOm3s6'
aes = AES256Crypto(key, Mode.CBC, Padding.SPACE, iv)
text_1 = aes.encrypt(text) 
# b'\xe7\x1d\xeae\xff\xc7\xc2\xd7\x8c\xf6\xe7\x82u\x7f\x168\xbc\x90\xad\x1e\x85M\xcb\xb0\xb4Ho\x1b\xe4\xec\x9d\x1d\xf93\xeb\x9b\xe7\xa3\xdd$\x8cEa\xab\xf7K~\x91H\xc3]5\xc4\x1a\xd4w[\x83\xb2"FC\x9f\x9d'
text_2 = aes.decrypt(text_1) 
# '{"upi": "1341343", "overdue": "2020-11-26 00:00:00"}'

import base64
text_3 = aes.encrypt(text, encode=base64.b16encode) 
# 'E71DEA65FFC7C2D78CF6E782757F1638BC90AD1E854DCBB0B4486F1BE4EC9D1DF933EB9BE7A3DD248C4561ABF74B7E9148C35D35C41AD4775B83B22246439F9D'
text_4 = aes.decrypt(text_3, decode=base64.b16decode)
# '{"upi": "1341343", "overdue": "2020-11-26 00:00:00"}'