python - 使用 pycrypto (RSA) 签名和验证数据

Question

我正在尝试熟悉 pycrypto 模块，但缺乏清晰的文档使事情变得困难。

首先，我想了解签名和验证数据。有人可以提供一个如何写的例子吗？

Answer 1

这是旧 PyCrypto 文档中示例的充实版本：

确保您正在使用pycryptodome而不是pycrypto（这是未维护的！）

pycryptodome 可以安装pip install pycryptodome

import Crypto.Hash.MD5 as MD5
import Crypto.PublicKey.RSA as RSA
import Crypto.PublicKey.DSA as DSA
import Crypto.PublicKey.ElGamal as ElGamal
import Crypto.Util.number as CUN
import os

plaintext = 'The rain in Spain falls mainly on the Plain'

# Here is a hash of the message
hash = MD5.new(plaintext).digest()
print(repr(hash))
# '\xb1./J\xa883\x974\xa4\xac\x1e\x1b!\xc8\x11'

for alg in (RSA, DSA, ElGamal):
    # Generates a fresh public/private key pair
    key = alg.generate(384, os.urandom)

    if alg == DSA:
        K = CUN.getRandomNumber(128, os.urandom)
    elif alg == ElGamal:
        K = CUN.getPrime(128, os.urandom)
        while CUN.GCD(K, key.p - 1) != 1:
            print('K not relatively prime with {n}'.format(n=key.p - 1))
            K = CUN.getPrime(128, os.urandom)
        # print('GCD({K},{n})=1'.format(K=K,n=key.p-1))
    else:
        K = ''

    # You sign the hash
    signature = key.sign(hash, K)
    print(len(signature), alg.__name__)
    # (1, 'Crypto.PublicKey.RSA')
    # (2, 'Crypto.PublicKey.DSA')
    # (2, 'Crypto.PublicKey.ElGamal')

    # You share pubkey with Friend
    pubkey = key.publickey()

    # You send message (plaintext) and signature to Friend.
    # Friend knows how to compute hash.
    # Friend verifies the message came from you this way:
    assert pubkey.verify(hash, signature)

    # A different hash should not pass the test.
    assert not pubkey.verify(hash[:-1], signature)

Answer 2

下面是我创建的用于执行所有必要的 RSA 功能（加密、解密、签名、验证签名和生成新密钥）的助手类

rsa.py

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

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)

示例使用

import rsa
from base64 import b64encode, b64decode

msg1 = "Hello Tony, I am Jarvis!"
msg2 = "Hello Toni, I am Jarvis!"
keysize = 2048
(public, private) = rsa.newkeys(keysize)
encrypted = b64encode(rsa.encrypt(msg1, public))
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)
print("Decrypted: '%s'" % decrypted)
print("Signature: " + signature)
print("Verify: %s" % verify)
rsa.verify(msg2, b64decode(signature), public)

Answer 3

根据以下文件：

https://www.dlitz.net/software/pycrypto/api/current/Crypto.PublicKey.RSA._RSAobj-class.html

您不应该在实际代码中使用 PyCrypto 中的 Crypto.PublicKey.RSA.sign 函数：

注意：此函数执行普通的原始 RSA 解密（教科书）。在实际应用中，您总是需要使用适当的加密填充，并且您不应该直接使用这种方法对数据进行签名。不这样做可能会导致安全漏洞。建议改用 Crypto.Signature.PKCS1_PSS 或 Crypto.Signature.PKCS1_v1_5 模块。

我最终使用了实现 PKCS1_v1_5的RSA 模块。签名文档非常简单。其他人建议使用 M2Crypto。