Click here to Skip to main content
15,028,332 members
Articles / Programming Languages / C#
Posted 19 Nov 2006


15 bookmarked

Emulating PBEWithMD5AndDES Encryption under .NET

Rate me:
Please Sign up or sign in to vote.
3.53/5 (6 votes)
19 Nov 2006CPOL
A class to provide the same behaviour as Java's PBEWithMD5AndDES encryption algorithm


In most ways, .NET's encryption model is pretty good. But when migrating secure applications from Java, the lack of this built in password-based encryption (PBE) is a pain. This article introduces a class that will encrypt data in the same way as Java's PBEWithMD5AndDES algorithm.

The implementation of the algorithm I use is adapted from this article by Michel Gallant.

The Algorithm

As the name suggests, this encryption algorithm uses the DES mechanism with a key generated by MD5 hashing the 'password', combined with a salt string. It allows the input string to be repeatedly MD5-hashed a number of times. The 16-byte MD5 string is then split into two halves, an 8-byte DES key and an 8-byte initial seed for DES.

It obviously makes sense to make use of .NET's DESCryptoServiceProvider to provide the encryption. So this implementation is simply doing the multiple MD5 hash.

The Code

To use this class, simply use:

PKCSKeyProvider kp = new PKCSKeyProvider();
ICryptoTransform crypt = kp.Generate(
      new byte[] { 100, 200, 255, 3},  // salt
      15,             // iterations of MD5 hashing
      1 );  // number of 16-byte segments to create. 
            // 1 to mimic Java behaviour.

Complete class listing:

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace RedCorona.Cryptography {
    public class PKCSKeyGenerator {
        byte[] key = new byte[8], iv = new byte[8];
        DESCryptoServiceProvider des = new DESCryptoServiceProvider();
        public byte[] Key { get { return key; } }
        public byte[] IV { get { return iv; } }
        public ICryptoTransform Encryptor { get { return des.CreateEncryptor(key, iv); } }
        public PKCSKeyGenerator(){}
        public PKCSKeyGenerator(String keystring, byte[] salt, 
		int md5iterations, int segments){
            Generate(keystring, salt, md5iterations, segments);
        public ICryptoTransform Generate(String keystring, byte[] salt, 
		int md5iterations, int segments){
            int HASHLENGTH = 16;    //MD5 bytes
            byte[] keymaterial = 
	    new byte[HASHLENGTH*segments] ; //to store concatenated Mi hashed results
            // --- get secret password bytes ----
            byte[] psbytes;
            psbytes = Encoding.UTF8.GetBytes(keystring);
            // --- concatenate salt and pswd bytes into fixed data array ---
            byte[] data00 = new byte[psbytes.Length + salt.Length] ;
            Array.Copy(psbytes, data00, psbytes.Length);  //copy the pswd bytes
            Array.Copy(salt, 0, data00, 
		psbytes.Length, salt.Length) ;//concatenate the salt bytes
            // ---- do multi-hashing and concatenate results  D1, D2 ...  
            // into keymaterial bytes ----
            MD5 md5 = new MD5CryptoServiceProvider();
            byte[] result = null;
            byte[] hashtarget = new byte[HASHLENGTH + 
		data00.Length];   //fixed length initial hashtarget
            for(int j=0; j<segments; j++) {
                // ----  Now hash consecutively for md5iterations times ------
                if(j == 0) result = data00;       //initialize
                else {
                    Array.Copy(result, hashtarget, result.Length);
                    Array.Copy(data00, 0, hashtarget, result.Length, data00.Length) ;
                    result = hashtarget;
                for(int i=0; i<md5iterations; i++)
                    result = md5.ComputeHash(result);
                Array.Copy(result, 0, keymaterial, j*HASHLENGTH, 
			result.Length);  //concatenate to keymaterial
            Array.Copy(keymaterial, 0, key, 0, 8);
            Array.Copy(keymaterial, 8, iv, 0, 8);
            return Encryptor;


  • 19th November, 2006: Initial post


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

United Kingdom United Kingdom
I'm a recent graduate (MSci) from the University of Cambridge, no longer studying Geology. Programming is a hobby so I get to write all the cool things and not all the boring things Smile | :) . However I now have a job in which I have to do a bit of work with a computer too.

Comments and Discussions

QuestionWays to decrypt the encryption Pin
Ace Neo8-May-19 20:55
MemberAce Neo8-May-19 20:55 
Questionfor decrypt Pin
Mansuri Amin10-Dec-15 1:29
MemberMansuri Amin10-Dec-15 1:29 
AnswerRe: for decrypt Pin
Ace Neo8-May-19 21:12
MemberAce Neo8-May-19 21:12 
GeneralError in IV property Pin
tHermO7825-Aug-08 2:43
MembertHermO7825-Aug-08 2:43 
GeneralRe: Error in IV property Pin
BobJanova25-Aug-08 11:57
MemberBobJanova25-Aug-08 11:57 
GeneralLicense Pin
Justin Porter17-Jul-08 9:45
MemberJustin Porter17-Jul-08 9:45 
GeneralRe: License Pin
BobJanova17-Jul-08 11:01
MemberBobJanova17-Jul-08 11:01 
GeneralRe: License Pin
Justin Porter18-Jul-08 9:12
MemberJustin Porter18-Jul-08 9:12 
GeneralNice! Pin
Titanio18-Apr-07 2:32
MemberTitanio18-Apr-07 2:32 
GeneralAdapting for PBEWithMD5AndTripleDES Pin
kyoseix14-Feb-07 8:28
Memberkyoseix14-Feb-07 8:28 
QuestionRe: Adapting for PBEWithMD5AndTripleDES Pin
BobJanova14-Feb-07 8:50
MemberBobJanova14-Feb-07 8:50 
QuestionUsing this in .net Pin
BlahMatt7-Feb-07 7:23
MemberBlahMatt7-Feb-07 7:23 
AnswerRe: Using this in .net Pin
BobJanova7-Feb-07 7:40
MemberBobJanova7-Feb-07 7:40 
GeneralRe: Using this in .net [modified] Pin
BlahMatt7-Feb-07 8:22
MemberBlahMatt7-Feb-07 8:22 
GeneralRe: Using this in .net Pin
irfanhaleem@hotmail.com6-Jul-10 1:33
Memberirfanhaleem@hotmail.com6-Jul-10 1:33 
GeneralRe: Using this in .net Pin
BobJanova6-Jul-10 1:43
MemberBobJanova6-Jul-10 1:43 
QuestionDecryption? Pin
Audiedog29-Nov-06 9:49
MemberAudiedog29-Nov-06 9:49 
AnswerRe: Decryption? Pin
BobJanova29-Nov-06 13:27
MemberBobJanova29-Nov-06 13:27 
GeneralRe: Decryption? Pin
Audiedog30-Nov-06 6:06
MemberAudiedog30-Nov-06 6:06 
GeneralRe: Decryption? Pin
ckl_886-Jan-07 23:32
Memberckl_886-Jan-07 23:32 
GeneralRe: Decryption? Pin
ckl_887-Jan-07 15:02
Memberckl_887-Jan-07 15:02 
GeneralRe: Decryption? Pin
cordobes13-Oct-08 5:27
Membercordobes13-Oct-08 5:27 
GeneralRe: Decryption? Pin
ozkan.pakdil13-Nov-08 22:53
Memberozkan.pakdil13-Nov-08 22:53 
GeneralRe: Decryption? Pin
jgonzalez7178-Jul-11 6:38
Memberjgonzalez7178-Jul-11 6:38 
GeneralRe: Decryption? Pin
Member 1171610912-May-21 19:01
MemberMember 1171610912-May-21 19:01 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.