在 Python 2.7 中复制 Java 的 PBEWithMD5AndDES

Question

如果不是很明显，让我先说我不是加密人。

我的任务是在 Python 2.7 中复制 Java 的 PBEWithMD5AndDES（带 DES 加密的 MD5 摘要）的行为。

我确实可以使用 Python 的加密工具包 PyCrypto。

这是我试图复制其行为的 Java 代码：

import java.security.spec.KeySpec;
import javax.crypto.spec.PBEKeySpec;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import java.security.spec.AlgorithmParameterSpec;
import javax.crypto.spec.PBEParameterSpec;
import javax.crypto.Cipher;
import javax.xml.bind.DatatypeConverter;

public class EncryptInJava
{
    public static void main(String[] args)
    {
      String encryptionPassword = "q1w2e3r4t5y6";
      byte[] salt = { -128, 64, -32, 16, -8, 4, -2, 1 };
      int iterations = 50;

      try
      {
        KeySpec keySpec = new PBEKeySpec(encryptionPassword.toCharArray(), salt, iterations);
        SecretKey key = SecretKeyFactory.getInstance("PBEWithMD5AndDES").generateSecret(keySpec);
        AlgorithmParameterSpec paramSpec = new PBEParameterSpec(salt, iterations);

        Cipher encoder = Cipher.getInstance(key.getAlgorithm());
        encoder.init(Cipher.ENCRYPT_MODE, key, paramSpec);

        String str_to_encrypt = "MyP455w0rd";
        byte[] enc = encoder.doFinal(str_to_encrypt.getBytes("UTF8"));

        System.out.println("encrypted = " + DatatypeConverter.printBase64Binary(enc));
      }
      catch (Exception e)
      {
        e.printStackTrace();
      }
    }
}

对于给定的值，它会输出以下内容：

encrypted = Icy6sAP7adLgRoXNYe9N8A==

这是我将上述内容移植到 Python 的笨拙尝试，encrypt_in_python.py：

from Crypto.Hash import MD5
from Crypto.Cipher import DES

_password = 'q1w2e3r4t5y6'
_salt = '\x80\x40\xe0\x10\xf8\x04\xfe\x01'
_iterations = 50
plaintext_to_encrypt = 'MyP455w0rd'

if "__main__" == __name__:

    """Mimic Java's PBEWithMD5AndDES algorithm to produce a DES key"""
    hasher = MD5.new()
    hasher.update(_password)
    hasher.update(_salt)
    result = hasher.digest()

    for i in range(1, _iterations):
        hasher = MD5.new()
        hasher.update(result)
        result = hasher.digest()

    key = result[:8]

    encoder = DES.new(key)
    encrypted = encoder.encrypt(plaintext_to_encrypt + ' ' * (8 - (len(plaintext_to_encrypt) % 8)))
    print encrypted.encode('base64')

它输出一个完全不同的字符串。

是否可以将 Java 实现移植到具有标准 Python 库的 Python 实现？

显然，Python 实现要求我加密的明文是 8 个字符的倍数，我什至不确定如何填充明文输入以满足该条件。

感谢您的帮助。

Answer 1

感谢 GregS 的评论，我才能够解决这个转换问题！

为了将来参考，这个 Python 代码模仿了上面 Java 代码的行为：

from Crypto.Hash import MD5
from Crypto.Cipher import DES

_password = 'q1w2e3r4t5y6'
_salt = '\x80\x40\xe0\x10\xf8\x04\xfe\x01'
_iterations = 50
plaintext_to_encrypt = 'MyP455w0rd'

# Pad plaintext per RFC 2898 Section 6.1
padding = 8 - len(plaintext_to_encrypt) % 8
plaintext_to_encrypt += chr(padding) * padding

if "__main__" == __name__:

    """Mimic Java's PBEWithMD5AndDES algorithm to produce a DES key"""
    hasher = MD5.new()
    hasher.update(_password)
    hasher.update(_salt)
    result = hasher.digest()

    for i in range(1, _iterations):
        hasher = MD5.new()
        hasher.update(result)
        result = hasher.digest()

    encoder = DES.new(result[:8], DES.MODE_CBC, result[8:16])
    encrypted = encoder.encrypt(plaintext_to_encrypt)

    print encrypted.encode('base64')

此 Python 代码在 Python 2.7 中输出以下内容：

Icy6sAP7adLgRoXNYe9N8A==

再次感谢 GregS 为我指明了正确的方向！

Answer 2

对于 Python 3.6，我使用以下代码进行了测试，与上面稍作改动即可使用：

from Crypto.Hash import MD5
from Crypto.Cipher import DES
import base64
import re

_password = b'q1w2e3r4t5y6'
_salt = b'\x80\x40\xe0\x10\xf8\x04\xfe\x01'

_iterations = 50

plaintext_to_encrypt = 'MyP455w0rd'

# Pad plaintext per RFC 2898 Section 6.1
padding = 8 - len(plaintext_to_encrypt) % 8
plaintext_to_encrypt += chr(padding) * padding

if "__main__" == __name__:

    """Mimic Java's PBEWithMD5AndDES algorithm to produce a DES key"""
    hasher = MD5.new()
    hasher.update(_password)
    hasher.update(_salt)
    result = hasher.digest()

    for i in range(1, _iterations):
        hasher = MD5.new()
        hasher.update(result)
        result = hasher.digest()

    encoder = DES.new(result[:8], DES.MODE_CBC, result[8:16])
    encrypted = encoder.encrypt(plaintext_to_encrypt)

    print (str(base64.b64encode(encrypted),'utf-8'))

    decoder = DES.new(result[:8], DES.MODE_CBC, result[8:])
    d = str(decoder.decrypt(encrypted),'utf-8')
    print (re.sub(r'[\x01-\x08]','',d))

输出：

Icy6sAP7adLgRoXNYe9N8A==

MyP455w0rd

Answer 3

我从here找到了一个

import base64
import hashlib
import re
import os
from Crypto.Cipher import DES
def get_derived_key(password, salt, count):
    key = password + salt
    for i in range(count):
        m = hashlib.md5(key)
        key = m.digest()
    return (key[:8], key[8:])
def decrypt(msg, password):
    msg_bytes = base64.b64decode(msg)
    salt = '\xA9\x9B\xC8\x32\x56\x35\xE3\x03'
    enc_text = msg_bytes
    (dk, iv) = get_derived_key(password, salt, 2)
    crypter = DES.new(dk, DES.MODE_CBC, iv)
    text = crypter.decrypt(enc_text)
    return re.sub(r'[\x01-\x08]','',text)
def encrypt(msg, password):
    salt = '\xA9\x9B\xC8\x32\x56\x35\xE3\x03'
    pad_num = 8 - (len(msg) % 8)
    for i in range(pad_num):
        msg += chr(pad_num)
    (dk, iv) = get_derived_key(password, salt, 2)
    crypter = DES.new(dk, DES.MODE_CBC, iv)
    enc_text = crypter.encrypt(msg)
    return base64.b64encode(enc_text)
def main():
    msg = "hello"
    passwd = "xxxxxxxxxxxxxx"
    encrypted_msg = encrypt(msg, passwd)
    print encrypted_msg
    plain_msg = decrypt(encrypted_msg, passwd)
    print plain_msg
if __name__ == "__main__":
    main()

Answer 4

如果您在 Python 3 中使用较新的 Cryptodome 库，您还需要将您的 plaintext_to_encrypt 编码为“latin-1”，如下所示。

from Cryptodome.Hash import MD5
from Cryptodome.Cipher import DES
import base64
import re

_password = b'q1w2e3r4t5y6'
_salt = b'\x80\x40\xe0\x10\xf8\x04\xfe\x01'

_iterations = 50

plaintext_to_encrypt = 'MyP455w0rd'

# Pad plaintext per RFC 2898 Section 6.1
padding = 8 - len(plaintext_to_encrypt) % 8
plaintext_to_encrypt += chr(padding) * padding

if "__main__" == __name__:

    """Mimic Java's PBEWithMD5AndDES algorithm to produce a DES key"""
    hasher = MD5.new()
    hasher.update(_password)
    hasher.update(_salt)
    result = hasher.digest()

    for i in range(1, _iterations):
        hasher = MD5.new()
        hasher.update(result)
        result = hasher.digest()

    encoder = DES.new(result[:8], DES.MODE_CBC, result[8:16])
    encrypted = encoder.encrypt(plaintext_to_encrypt.encode('latin-1'))  #encoded plaintext

    print (str(base64.b64encode(encrypted),'utf-8'))

    decoder = DES.new(result[:8], DES.MODE_CBC, result[8:])
    d = str(decoder.decrypt(encrypted),'utf-8')
    print (re.sub(r'[\x01-\x08]','',d))