1.CryptoTest模块，该模块包括四个类，分别是是aestest、hashtest、rsatest和signverify。
 # CryptoTest.py
# 封装4个类
from Crypto.Cipher import AES
from binascii import b2a_hex, a2b_hex
import hashlib, base64
from Crypto.Cipher import PKCS1_OAEP
from Crypto.PublicKey import RSA
from Crypto.Signature import PKCS1_v1_5
from Crypto.Hash import SHA256


# AES算法类，实现AES的加密和解密
class aestest():
    def __init__(self, key):
        self.key = key
        self.mode = AES.MODE_CBC

    def encrypt(self, text):
        cryptor = AES.new(self.key, self.mode, self.key)
        text = text.encode("utf-8")
        length = 16
        count = len(text)
        add = length - (count % length)
        text = text + (b'\0' * add)
        self.ciphertext = cryptor.encrypt(text)
        entext = b2a_hex(self.ciphertext).decode("utf-8")
        # ciphertext.bin是生成的密文文件
        with open('ciphertext.bin', 'w') as f1:
            f1.write(entext)
        return entext

    def decrypt(self, text):
        cryptor = AES.new(self.key, self.mode, self.key)
        plain_text = cryptor.decrypt(a2b_hex(text))
        plaintext = plain_text.rstrip(b'\0').decode("utf-8")
        with open('plaintext.bin', 'w') as f2:
            f2.write(plaintext)
        return plaintext


# hash类，实现摘要值的计算
class hashtest():
    hash = hashlib.sha256()
    hash.update('admin'.encode('utf-8'))


# RSA类，实现密钥产生、加密和解密
class rsatest():
    privkey = []
    pubkey = []

    def generatekeys(self, file1, file2):
        key = RSA.generate(2048)
        encrypted_key = key.exportKey(pkcs=8)
        self.privkey = encrypted_key
        self.pubkey = key.publickey().exportKey()
        with open(file1, 'wb') as f:
            f.write(encrypted_key)
        with open(file2, 'wb') as f:
            f.write(key.publickey().exportKey())

    def encrypt(self, file, encryptedfile, pubk):
        with open(file, 'rb') as f:
            recipient_key = RSA.import_key(open(pubk).read())
            cipher_rsa = PKCS1_OAEP.new(recipient_key)
            c = cipher_rsa.encrypt(f.read())
            with open(encryptedfile, 'wb') as out_file:
                out_file.write(c)

    def decrypt(self, file, decryptedfile, prik):
        with open(file, 'rb') as f:
            private_key = RSA.import_key(open(prik).read())
            cipher_rsa = PKCS1_OAEP.new(private_key)
            m = cipher_rsa.decrypt(f.read())
            with open(decryptedfile, 'wb') as out_file:
                out_file.write(m)


# 签名验证类，实现RSA算法的签名和验证
class signverify:
    def sign(self, data, privkeyfile, sigfile):
        privkey = open(privkeyfile,\ "rb").read().decode("utf-8")
        key = RSA.importKey(privkey)
        data1 = open(data, "rb").read()
        h = SHA256.new(data1)
        signer = PKCS1_v1_5.new(key)
        signature = signer.sign(h)
        sig = base64.b64encode(signature)
        with open(sigfile, "wb") as f:
            f.write(sig)

    def verify(self, data, pubkeyfile, sigfile):
        publickey = open(pubkeyfile,\ "rb").read().decode("utf-8")
        key = RSA.importKey(publickey)
        data1 = open(data, "rb").read()
        h = SHA256.new(data1)
        verifier = PKCS1_v1_5.new(key)
        signature = open(sigfile, "rb").read().decode('utf-8')
        if verifier.verify(h, base64.b64decode(signature)):
            return True
        return False


2.发送方和接收方产生自己的公钥
  # RSAkey.py
# 发送方和接收分别执行产生自己的公私钥

import CryptoTest

if __name__ == '__main__':
    myrsa = CryptoTest.rsatest()
    file1 = input()  # 私钥
    file2 = input()  # 公钥
    myrsa.generatekeys(file1, file2)

3.发送方的操作封包过程
 # sender.py
# 发送发封包过程
import CryptoTest

# 发送方A的三步，发送方A已经获得接收方B的公钥Bpubkey.bin

# 第1步，用AES对称密钥加密明文文件
with open('aeskey.txt', 'rb') as f:  # aeskey.txt是对称密钥文件
    aessymkey = f.read()
Aaestest = CryptoTest.aestest(aessymkey)  # 实例化对象
print('请输入要加密的明文文件')
fname = input()  # 输入要加密的明文文件
with open(fname, 'r') as f:
    m = f.read()
    Aaestest.encrypt(m)  # AES的CBC模式加密
print("明文文件加密后的密文文件是ciphertext.bin")

# 第2步，用对方公钥Bpubkey.bin加密  对称密钥文件aeskey.txt
Arsa = CryptoTest.rsatest()
Arsa.encrypt('aeskey.txt', 'keyencrypted.bin', 'Bpubkey.bin')
print("对称密钥文件aeskey.txt加密后的文件是keyencrypted.bin")

# 第3步，生成明文的摘要值，用自己的私钥Aprikey.bin对摘要值签名
asign = CryptoTest.signverify()
asign.sign('data.txt', 'Aprikey.bin', 'digitalsign.bin')
print("A签名后的文件是digitalsign.bin")
print("将三个文件ciphertext.bin，keyencrypted.bin，\
     digitalsign.bin发送给接收方")