chenxi
chenxi

Reputation: 23

DES in python can't get the correct encoded data using pycrypto

I hava a algorithm to encrypt data in java ,I want to rewrite it in python.But the two algorithm can't get the same encoded data. java code is :

String strDefaultKey = "QabC-+50";
Key key = new SecretKeySpec(strDefaultKey.getBytes("UTF-8"), "DES");
encryptCipher = Cipher.getInstance(DES_ECB);
encryptCipher.init(Cipher.ENCRYPT_MODE, key);
String seed = "2016-09-19 05:11";
MessageDigest md5 = MessageDigest.getInstance("MD5");
md5.update(seed.getBytes());
byte[] m = md5.digest();
encryptCipher.doFinal(m);
byte[] encodeUrl = Base64.encodeBase64(sEncription.encrypt(m));
String finalUrl = new String(encodeUrl);
finalResult = finalUrl.substring(2, 8) + finalUrl.substring(10, 13);

my python code is:

m = 'QabC-+50'
text = '2016-09-19 05:11'
md5 = MD5.new()
md5.update(text)
text = md5.hexdigest()

cipher = DES.new(m, DES.MODE_ECB)
text_temp = cipher.encrypt(text)
final_str = base64.b64encode(text_temp)
print final_str
print final_str[2:8] + final_str[10:13]
print type(text_temp)

The two version codes can't get the same final string. Does anybody know why?

Upvotes: 2

Views: 1082

Answers (1)

tianwei
tianwei

Reputation: 1879

You crypto logic is ok,the difference between the two methods is their MD5 result.

Without the MD5 step:

Java code(I don't know what your sEncription is,remove it):

import java.security.Key;
import java.security.MessageDigest;
import java.util.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;


public class H {
    public static void main(String args[]){
        try{
        String strDefaultKey = "QabC-+50";
        Key key = new SecretKeySpec(strDefaultKey.getBytes("UTF-8"), "DES");
        Cipher encryptCipher = Cipher.getInstance("DES/ECB/NoPadding");
        encryptCipher.init(Cipher.ENCRYPT_MODE, key);
        String seed = "2016-09-19 05:11";
        byte[] a = encryptCipher.doFinal(seed.getBytes());
        byte[] encodeUrl = Base64.getEncoder().encode(a);
//      byte[] encodeUrl = Base64.encodeBase64(sEncription.encrypt(m));
        String finalUrl = new String(encodeUrl);
        String finalResult = finalUrl.substring(2, 8) + finalUrl.substring(10, 13);
        System.out.println(finalUrl);
        System.out.println(finalResult);
        }catch(Exception e){
            e.printStackTrace();
        }
    }
}

OUTPUT:

Wm+DLy8m9G2BJnH2wvtKvA==
+DLy8m2BJ

Python Code:

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

m = 'QabC-+50'
text = '2016-09-19 05:11'
md5 = MD5.new()
md5.update(text)
# text = md5.hexdigest()
cipher = DES.new(m, DES.MODE_ECB)
text_temp = cipher.encrypt(text)
print 'text_temp is ', text_temp
final_str = base64.b64encode(text_temp)
print final_str
print final_str[2:8] + final_str[10:13]

OUTPUT:

Wm+DLy8m9G2BJnH2wvtKvA==
+DLy8m2BJ

So without the MD5 step,the java code and the python code have the some output.

What does matter is the MD5 method in the java code, it is not a right way to get the MD5 value of a string.

Code below contains the right way to get the string's MD5 value:

import java.security.Key;
import java.security.MessageDigest;
import java.util.Base64;

import javax.crypto.Cipher;
import javax.crypto.spec.SecretKeySpec;


public class H {
    public static void main(String args[]){
        try{
        String strDefaultKey = "QabC-+50";
        Key key = new SecretKeySpec(strDefaultKey.getBytes("UTF-8"), "DES");
        Cipher encryptCipher = Cipher.getInstance("DES/ECB/NoPadding");
        encryptCipher.init(Cipher.ENCRYPT_MODE, key);
        String seed = "2016-09-19 05:11";
        String seedMd5 = MD5(seed);
        byte[] a = encryptCipher.doFinal(seedMd5.getBytes());
        byte[] encodeUrl = Base64.getEncoder().encode(a);
        String finalUrl = new String(encodeUrl);
        String finalResult = finalUrl.substring(2, 8) + finalUrl.substring(10, 13);
        System.out.println(finalUrl);
        System.out.println(finalResult);
        }catch(Exception e){
            e.printStackTrace();
        }
    }

    static String MD5(String src) {
        MessageDigest md;
        try {
            md = MessageDigest.getInstance("MD5");
            StringBuffer deviceIDString = new StringBuffer(src);
            src = convertToHex(md.digest(deviceIDString.toString().getBytes()));
        } catch (Exception e) {
            src = "00000000000000000000000000000000";
        }
        return src;
    }

    private static String convertToHex(byte[] data) {
        StringBuffer buf = new StringBuffer();
        for (int i = 0; i < data.length; i++) {
            int halfbyte = (data[i] >>> 4) & 0x0F;
            int two_halfs = 0;
            do {
                if ((0 <= halfbyte) && (halfbyte <= 9))
                    buf.append((char) ('0' + halfbyte));
                else
                    buf.append((char) ('a' + (halfbyte - 10)));
                halfbyte = data[i] & 0x0F;
            } while (two_halfs++ < 1);
        }
        return buf.toString();
    }
}

OUTPUT:

c/C16RAE1fADZXNi2H0YlevNhuucGYYHGVQ7v0Eoo9w=
C16RAEADZ

Python Code:

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

m = 'QabC-+50'
text = '2016-09-19 05:11'
md5 = MD5.new()
md5.update(text)
text = md5.hexdigest()
cipher = DES.new(m, DES.MODE_ECB)
text_temp = cipher.encrypt(text)
final_str = base64.b64encode(text_temp)
print final_str
print final_str[2:8] + final_str[10:13]

OUTPUT:

c/C16RAE1fADZXNi2H0YlevNhuucGYYHGVQ7v0Eoo9w=
C16RAEADZ

Now everything is ok! :)

Upvotes: 2

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