Why my hash value comparison is false?

[Mohammad Ashari Rahman]

Hi guys. What I am doing wrong? I thought I generate salt for a user then get hash, then compare this with password input and the user salt to make them equal.
My hash values are not comparing to be equal..please help

/*
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package testhashing;

import java.math.BigInteger;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.util.Scanner;

/**
 *
 * @author ashari
 */
public class TestHashing {

    private byte []salt;
    private String pass, name;
    /* @param args the command line arguments
     */
    public void setPass(String pas){
        pass=pas;
    }
        public void setName(String nam){
            name=nam;
    }
            public String getPass(){
                return pass;
    }
            public String getname(){
            return name;}
            
      public byte[] getSalt(){
          salt=new byte[8];
         boolean comp=false;
        SecureRandom rand=new SecureRandom();
        rand.nextBytes(salt);
        return salt;
      }
     public String hash(){
        MessageDigest msg=null;
        //boolean comp=false;
        try{
         msg=MessageDigest.getInstance("MD5");
        msg.update((this.getSalt()+this.getPass()).getBytes());
        }
        catch(NoSuchAlgorithmException x){
        
        }
         this.pass=(new BigInteger(msg.digest()).toString());
         System.out.println("Internal hash value for karim "+this.pass);
         return this.pass; 
     }   
     public boolean compare(String gen){
         boolean isTrue=false;
         if((this.pass).equals(gen))
              isTrue=true;
         else
             isTrue=false;
        return isTrue;
     }
    public static void main(String[] args) {
        // TODO code application logic here
        Scanner in=new Scanner(System.in);
        
        for(int i=0;i<3;i++){
        TestHashing tst=new TestHashing();
        MessageDigest msg=null;
        String details, genHash;
        tst.setName("kerim");
        tst.setPass("good");
        tst.getSalt();
        tst.hash();
        //byte [] salting=new byte[8];
        
        details=in.nextLine();
        //tst.setPass(details);
        //SecureRandom rand=new SecureRandom();
        //rand.nextBytes(tst.getSalt());
        try{
         msg=MessageDigest.getInstance("MD5");
        msg.update((tst.getSalt()+details).getBytes());
        }
        catch(NoSuchAlgorithmException x){
        
        }
         genHash=(new BigInteger(msg.digest()).toString());
         System.out.println("Hash value generated for "+tst.getname()+" "+genHash);
         System.out.println(tst.compare(genHash));
        }
       
        
    }
    
}

[Jesper de Jong]

One thing that looks suspicious about your code is that the getSalt() method computes a new random salt every time that you call it.

That's probably the cause of the problems. You should compute a new salt once, and then use that computed value, instead of computing a new value each time in getSalt().

[Campbell Ritchie]

And welcome to the Ranch

[Paweł Baczyński]

It's offtopic and nitpicky...

Instead of

public boolean compare(String gen){
    boolean isTrue=false;
    if((this.pass).equals(gen))
        isTrue=true;
    else
        isTrue=false;
    return isTrue;
}

you could write

public boolean compare(String gen){
    return this.pass.equals(gen);
}

[Mohammad Ashari Rahman]

Thanks a lot guys..and glad to be here