How to decode hash password?

[lockdog]

Seamspace example:

package org.teamdev.librarian.user;

import org.apache.commons.codec.binary.Hex;
import org.jboss.seam.Component;
import org.jboss.seam.annotations.Name;

import java.security.MessageDigest;

@Name("hash")
public class Hash {
 String hashFunction = "MD5";
 String charset = "UTF-8";

 public String hash(String password) {
 try {
 MessageDigest md = MessageDigest.getInstance(hashFunction);
 md.update(password.getBytes(charset));
 byte[] raw = md.digest();
 return new String(Hex.encodeHex(raw));
 }
 catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

 public String getCharset() {
 return charset;
 }

 public void setCharset(String charset) {
 this.charset = charset;
 }

 public String getHashFunction() {
 return hashFunction;
 }

 public void setHashFunction(String hashFunction) {
 this.hashFunction = hashFunction;
 }

 public static Hash instance() {
 return (Hash) Component.getInstance(Hash.class);
 }
}

How to decode (unhash) password?

public String unHash(String hashedPassword) {
 try {
 MessageDigest md = MessageDigest.getInstance(hashFunction);
 md.update(hashedPassword.getBytes(charset));
 char[] raw = md.digest().toString().toCharArray();
 return new String(Hex.decodeHex(raw));
 }
 catch (Exception e) {
 throw new RuntimeException(e);
 }
 }

Don't work =(

[cfthomas]

Hi LockDock!

It's okay that it doesn't work.
Hashing is a one-way procedure. No Hash can be 'decoded' to the original value.
What you are doing in your unHash method is hashing the hash again!
If you want to scramble passwords and unscramble them at a later time you need to look for Encryption/Decryption.
It can also be done with the Java Cryptography API.

Try this: http://www.devx.com/Java/10MinuteSolution/21385/1763/page/2

rgds,

Thomas