如何在python中使用RSA私钥加密？

Question

是否可以使用pycryptodome或任何其他库在python中使用私钥对消息进行加密？我知道您不应该使用私钥进行加密，而不能使用公钥进行解密，但是我的目的是使用私钥进行加密，以便接收者可以确定邮件是由真实作者发送的。除了寻找安全加密以外，我还在寻找某种模糊处理。我想做一个消息公开的应用程序，但是只有拥有公共密钥才能看到。我试图做到这一点：

from Crypto import Random
from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
import base64


def generate_keys():
    modulus_lenght = 256 * 4
    private_key = RSA.generate(modulus_lenght, Random.new().read)
    public_key = private_key.publickey()
    return private_key, public_key

def encrypt_private_key(a_message, private_key):
    encryptor = PKCS1_OAEP.new(private_key)
    encrypted_msg = encryptor.encrypt(a_message)
    encoded_encrypted_msg = base64.b64encode(encrypted_msg)
   return encoded_encrypted_msg

def decrypt_public_key(encoded_encrypted_msg, public_key):
    encryptor = PKCS1_OAEP.new(public_key)
    decoded_encrypted_msg = base64.b64decode(encoded_encrypted_msg)
    decoded_decrypted_msg = encryptor.decrypt(decoded_encrypted_msg)
    return decoded_decrypted_msg

private_key, public_key = generate_keys()

message = "Hello world"

encoded = encrypt_private_key(message, private_key)
decoded = decrypt_public_key(encoded, public_key)

print decoded

但这会引发下一个错误：TypeError：这不是私钥。

Answer 1

简短答案

• 出于安全原因，您正在使用的代码不允许您执行此操作
• 下面的替代代码

长答案

我很好奇您的问题，然后我开始尝试编码

一段时间后，我意识到，如果您运行此代码段，您将看到它正确运行：

#!/usr/bin/env python

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
import base64

def generate_keys():
    modulus_length = 1024

    key = RSA.generate(modulus_length)
    #print (key.exportKey())

    pub_key = key.publickey()
    #print (pub_key.exportKey())

    return key, pub_key

def encrypt_private_key(a_message, private_key):
    encryptor = PKCS1_OAEP.new(private_key)
    encrypted_msg = encryptor.encrypt(a_message)
    print(encrypted_msg)
    encoded_encrypted_msg = base64.b64encode(encrypted_msg)
    print(encoded_encrypted_msg)
    return encoded_encrypted_msg

def decrypt_public_key(encoded_encrypted_msg, public_key):
    encryptor = PKCS1_OAEP.new(public_key)
    decoded_encrypted_msg = base64.b64decode(encoded_encrypted_msg)
    print(decoded_encrypted_msg)
    decoded_decrypted_msg = encryptor.decrypt(decoded_encrypted_msg)
    print(decoded_decrypted_msg)
    #return decoded_decrypted_msg

def main():
  private, public = generate_keys()
  print (private)
  message = b'Hello world'
  encoded = encrypt_private_key(message, public)
  decrypt_public_key(encoded, private)

if __name__== "__main__":
  main()

但是如果您现在将最后两行（即键的角色）更改为：

    encoded = encrypt_private_key(message, private)
    decrypt_public_key(encoded, public)

并重新运行该程序，您将获得 TypeError: No private key

让我引用这个好答案：

“事实证明，PyCrypto只是在试图防止您误认为另一个，例如OpenSSL或Ruby OpenSSL允许您同时执行以下操作：public_encrypt / public_decrypt和private_encrypt / private_decrypt

[...]

为了使结果在实践中可用，还需要注意其他事项。这就是为什么PyCrypto中有专用的签名包的原因-这有效地完成了您描述的内容，而且还照顾了我提到的内容”

修改此链接后，我来到了下面的代码，该代码可以解决您的问题：

# RSA helper class for pycrypto
# Copyright (c) Dennis Lee
# Date 21 Mar 2017

# Description:
# Python helper class to perform RSA encryption, decryption, 
# signing, verifying signatures & keys generation

# Dependencies Packages:
# pycrypto 

# Documentation:
# https://www.dlitz.net/software/pycrypto/api/2.6/

from Crypto.PublicKey import RSA
from Crypto.Cipher import PKCS1_OAEP
from Crypto.Signature import PKCS1_v1_5
from Crypto.Hash import SHA512, SHA384, SHA256, SHA, MD5
from Crypto import Random
from base64 import b64encode, b64decode
import rsa

hash = "SHA-256"

def newkeys(keysize):
    random_generator = Random.new().read
    key = RSA.generate(keysize, random_generator)
    private, public = key, key.publickey()
    return public, private

def importKey(externKey):
    return RSA.importKey(externKey)

def getpublickey(priv_key):
    return priv_key.publickey()

def encrypt(message, pub_key):
    #RSA encryption protocol according to PKCS#1 OAEP
    cipher = PKCS1_OAEP.new(pub_key)
    return cipher.encrypt(message)

def decrypt(ciphertext, priv_key):
    #RSA encryption protocol according to PKCS#1 OAEP
    cipher = PKCS1_OAEP.new(priv_key)
    return cipher.decrypt(ciphertext)

def sign(message, priv_key, hashAlg="SHA-256"):
    global hash
    hash = hashAlg
    signer = PKCS1_v1_5.new(priv_key)
    if (hash == "SHA-512"):
        digest = SHA512.new()
    elif (hash == "SHA-384"):
        digest = SHA384.new()
    elif (hash == "SHA-256"):
        digest = SHA256.new()
    elif (hash == "SHA-1"):
        digest = SHA.new()
    else:
        digest = MD5.new()
    digest.update(message)
    return signer.sign(digest)

def verify(message, signature, pub_key):
    signer = PKCS1_v1_5.new(pub_key)
    if (hash == "SHA-512"):
        digest = SHA512.new()
    elif (hash == "SHA-384"):
        digest = SHA384.new()
    elif (hash == "SHA-256"):
        digest = SHA256.new()
    elif (hash == "SHA-1"):
        digest = SHA.new()
    else:
        digest = MD5.new()
    digest.update(message)
    return signer.verify(digest, signature)

def main():
    msg1 = b"Hello Tony, I am Jarvis!"
    msg2 = b"Hello Toni, I am Jarvis!"

    keysize = 2048

    (public, private) = rsa.newkeys(keysize)

    # https://docs.python.org/3/library/base64.html
    # encodes the bytes-like object s
    # returns bytes
    encrypted = b64encode(rsa.encrypt(msg1, private))
    # decodes the Base64 encoded bytes-like object or ASCII string s
    # returns the decoded bytes
    decrypted = rsa.decrypt(b64decode(encrypted), private)
    signature = b64encode(rsa.sign(msg1, private, "SHA-512"))

    verify = rsa.verify(msg1, b64decode(signature), public)

    #print(private.exportKey('PEM'))
    #print(public.exportKey('PEM'))
    print("Encrypted: " + encrypted.decode('ascii'))
    print("Decrypted: '%s'" % (decrypted))
    print("Signature: " + signature.decode('ascii'))
    print("Verify: %s" % verify)
    rsa.verify(msg2, b64decode(signature), public)

if __name__== "__main__":
    main()

最后说明：

• 最后print■找ascii因为说这里 “为Base64的情况下，但是，所有的字符都是有效的ASCII字符”
• 在这种情况下，我们使用相同的密钥（私有密钥）进行加密和解密，所以是的：我们最终将是对称的，但是...
• 但是-如说在这里 - “公共密钥是公开-它的东西，你会很容易地共享，因此会很容易传播有与采用对称密码和共享密钥在这种情况下，没有任何附加值。”加“概念，”加密“使用私钥对签名消息更有用，而使用公钥的“解密”用于验证消息”
• 这个答案表达了相同的最后一个原则-“通常，我们说用私钥签名，然后用公钥验证”。