Python3对称加密算法AES、DES3实例详解

本文实例讲述了Python3对称加密算法AES、DES3。分享给大家供大家参考，具体如下：

python3.6此库安装方式，需要pip3 install pycryptodome。

如有site-packages中存在crypto、pycrypto，在pip之前，需要pip3 uninstall crypto、pip3 uninstall pycrypto，否则无法安装成功。

C:\WINDOWS\system32>pip3 install pycryptodome
Collecting pycryptodome
  Downloading https://files.pythonhosted.org/packages/0f/5d/a429a53eacae3e13143248c3868c76985bcd0d75858bd4c25b574e51bd4d/pycryptodome-3.6.3-cp36-cp36m-win_amd64.whl (7.9MB)
    100% |????????????????????????????????| 7.9MB 111kB/s
Installing collected packages: pycryptodome
Successfully installed pycryptodome-3.6.3

这里顺带说一下pycrypto，这个库已经有很久没有人维护了，如果需要安装此库，需要先安装 VC++ build tools

然后将 ~\BuildTools\VC\Tools\MSVC\14.15.26726\include 目录下的 stdint.h 拷贝到 C:\Program Files (x86)\Windows Kits\10\Include\10.0.17134.0\ucrt 下。（Win10 需管理员权限）

接着将同目录下的 inttypes.h 中的 #include <stdint.h> （第十四行），改成 #include "stdint.h"。

然后使用 pip3 install pycrypto，就能直接安装了。

注：如果不是业务需要，请尽可能使用 pycryptodome。

AES：

import Crypto.Cipher.AES
import Crypto.Random
import base64
import binascii
def auto_fill(x):
  if len(x) <= 32:
    while len(x) not in [16, 24, 32]:
      x += " "
    return x.encode()
  else:
    raise "密钥长度不能大于32位！"
key = "asd"
content = "abcdefg1234567"
x = Crypto.Cipher.AES.new(auto_fill(key), Crypto.Cipher.AES.MODE_ECB)
a = base64.encodebytes(x.encrypt(auto_fill(content)))
b = x.decrypt(base64.decodebytes(a))
print(a)
print(b)
a = binascii.b2a_base64(x.encrypt(auto_fill(content)))
b = x.decrypt(binascii.a2b_base64(a))
print(a)
print(b)
key = "dsa"
iv = Crypto.Random.new().read(16)  # 向量，必须为16字节
content = "1234567abcdefg"
y = Crypto.Cipher.AES.new(auto_fill(key), Crypto.Cipher.AES.MODE_CBC, iv)
c = binascii.b2a_base64(y.encrypt(auto_fill(content)))
z = Crypto.Cipher.AES.new(auto_fill(key), Crypto.Cipher.AES.MODE_CBC, iv)
d = z.decrypt(binascii.a2b_base64(c))
print(c)
print(d)

运行结果：

b'jr/EIUp32kLHc3ypZZ1cyg==\n'
b'abcdefg1234567  '
b'jr/EIUp32kLHc3ypZZ1cyg==\n'
b'abcdefg1234567  '
b'j+Ul9KQd0HnuiHW3z9tD7A==\n'
b'1234567abcdefg  '

DES3：

import Crypto.Cipher.DES3
import base64
import binascii
def auto_fill(x):
  if len(x) > 24:
    raise "密钥长度不能大于等于24位！"
  else:
    while len(x) < 16:
      x += " "
    return x.encode()
key = "asd"
content = "abcdefg1234567"
x = Crypto.Cipher.DES3.new(auto_fill(key), Crypto.Cipher.DES3.MODE_ECB)
a = base64.encodebytes(x.encrypt(auto_fill(content)))
print(a)
b = x.decrypt(base64.decodebytes(a))
print(b)
a = binascii.b2a_base64(x.encrypt(auto_fill(content)))
b = x.decrypt(binascii.a2b_base64(a))
print(a)
print(b)

运行结果：

b'/ee3NFKeNqEk/qMNd1mjog==\n'
b'abcdefg1234567  '
b'/ee3NFKeNqEk/qMNd1mjog==\n'
b'abcdefg1234567  '

附：AES的工厂模式封装Cipher_AES.py（封装Crypto.Cipher.AES）

'''
Created on 2018年7月7日
@author: ray
'''
import Crypto.Cipher.AES
import Crypto.Random
import base64
import binascii
class Cipher_AES:
  pad_default = lambda x, y: x + (y - len(x) % y) * " ".encode("utf-8")
  unpad_default = lambda x: x.rstrip()
  pad_user_defined = lambda x, y, z: x + (y - len(x) % y) * z.encode("utf-8")
  unpad_user_defined = lambda x, z: x.rstrip(z)
  pad_pkcs5 = lambda x, y: x + (y - len(x) % y) * chr(y - len(x) % y).encode("utf-8")
  unpad_pkcs5 = lambda x: x[:-ord(x[-1])]
  def __init__(self, key="abcdefgh12345678", iv=Crypto.Random.new().read(Crypto.Cipher.AES.block_size)):
    self.__key = key
    self.__iv = iv
  def set_key(self, key):
    self.__key = key
  def get_key(self):
    return self.__key
  def set_iv(self, iv):
    self.__iv = iv
  def get_iv(self):
    return self.__iv
  def Cipher_MODE_ECB(self):
    self.__x = Crypto.Cipher.AES.new(self.__key.encode("utf-8"), Crypto.Cipher.AES.MODE_ECB)
  def Cipher_MODE_CBC(self):
    self.__x = Crypto.Cipher.AES.new(self.__key.encode("utf-8"), Crypto.Cipher.AES.MODE_CBC, self.__iv.encode("utf-8"))
  def encrypt(self, text, cipher_method, pad_method="", code_method=""):
    if cipher_method.upper() == "MODE_ECB":
      self.Cipher_MODE_ECB()
    elif cipher_method.upper() == "MODE_CBC":
      self.Cipher_MODE_CBC()
    cipher_text = b"".join([self.__x.encrypt(i) for i in self.text_verify(text.encode("utf-8"), pad_method)])
    if code_method.lower() == "base64":
      return base64.encodebytes(cipher_text).decode("utf-8").rstrip()
    elif code_method.lower() == "hex":
      return binascii.b2a_hex(cipher_text).decode("utf-8").rstrip()
    else:
      return cipher_text.decode("utf-8").rstrip()
  def decrypt(self, cipher_text, cipher_method, pad_method="", code_method=""):
    if cipher_method.upper() == "MODE_ECB":
      self.Cipher_MODE_ECB()
    elif cipher_method.upper() == "MODE_CBC":
      self.Cipher_MODE_CBC()
    if code_method.lower() == "base64":
      cipher_text = base64.decodebytes(cipher_text.encode("utf-8"))
    elif code_method.lower() == "hex":
      cipher_text = binascii.a2b_hex(cipher_text.encode("utf-8"))
    else:
      cipher_text = cipher_text.encode("utf-8")
    return self.unpad_method(self.__x.decrypt(cipher_text).decode("utf-8"), pad_method)
  def text_verify(self, text, method):
    while len(text) > len(self.__key):
      text_slice = text[:len(self.__key)]
      text = text[len(self.__key):]
      yield text_slice
    else:
      if len(text) == len(self.__key):
        yield text
      else:
        yield self.pad_method(text, method)
  def pad_method(self, text, method):
    if method == "":
      return Cipher_AES.pad_default(text, len(self.__key))
    elif method == "PKCS5Padding":
      return Cipher_AES.pad_pkcs5(text, len(self.__key))
    else:
      return Cipher_AES.pad_user_defined(text, len(self.__key), method)
  def unpad_method(self, text, method):
    if method == "":
      return Cipher_AES.unpad_default(text)
    elif method == "PKCS5Padding":
      return Cipher_AES.unpad_pkcs5(text)
    else:
      return Cipher_AES.unpad_user_defined(text, method)

使用方法：

        加密：Cipher_AES(key [, iv]).encrypt(text, cipher_method [, pad_method [, code_method]])

        解密：Cipher_AES(key [, iv]).decrypt(cipher_text, cipher_method [, pad_method [, code_method]])

key：密钥（长度必须为16、24、32）

iv：向量（长度与密钥一致，ECB模式不需要）

text：明文（需要加密的内容）

cipher_text：密文（需要解密的内容）

cipher_method：加密方法，目前只有"MODE_ECB"、"MODE_CBC"两种

pad_method：填充方式，解决 Java 问题选用"PKCS5Padding"

code_method：编码方式，目前只有"base64"、"hex"两种

来段调用封装类 Cipher_AES 的 demo_Cipher_AES.py，方便大家理解：

import Cipher_AES
key = "qwedsazxc123321a"
iv = key[::-1]
text = "我爱小姐姐，可小姐姐不爱我 - -"
cipher_method = "MODE_CBC"
pad_method = "PKCS5Padding"
code_method = "base64"
cipher_text = Cipher_AES(key, iv).encrypt(text, cipher_method, pad_method, code_method)
print(cipher_text)
text = Cipher_AES(key, iv).decrypt(cipher_text, cipher_method, pad_method, code_method)
print(text)
'''
运行结果：
uxhf+MoSko4xa+jGOyzJvYH9n5NvrCwEHbwm/A977CmGqzg+fYE0GeL5/M5v9O1o
我爱小姐姐，可小姐姐不爱我 - -
'''