Compare two hash strings generated using SHA-1 in Android

Question

Here is the flow of my Android code:

I am using SHA-1 hashing to hash a password entered by the user via EditText. I get a hash string as output over here.

After that I am calling a SOAP web service (created using .NET framework) that performs the same SHA-1 hashing using ASCII encoding and returns me another hash string.

Now since the input string is same in both the cases, my hash strings are same as expected. See logcat below. But when I am comparing the hash strings, I am not getting the result as expected

Here is my Android code followed by logcat:

           package com.kar.encodePassword;
           import java.io.IOException;
           import java.io.UnsupportedEncodingException;
           import java.net.SocketException;
           import java.security.MessageDigest;
           import java.security.NoSuchAlgorithmException;
           import org.ksoap2.SoapEnvelope;
           import org.ksoap2.serialization.SoapObject;
           import org.ksoap2.serialization.SoapPrimitive;
           import org.ksoap2.serialization.SoapSerializationEnvelope;
           import org.ksoap2.transport.HttpTransportSE;
           import org.xmlpull.v1.XmlPullParserException;
           import android.app.Activity;
           import android.os.Bundle;
           import android.util.Base64;
           import android.util.Log;
           import android.view.View;
           import android.widget.Button;
           import android.widget.EditText;
           import android.widget.Toast;

   public class PaswordencodingActivity extends Activity {
       /** Called when the activity is first created. */

 private static final String soap_action = "http://tempuri.org/HashCode";
 private static final String method_name = "HashCode";
 private static final String namespace2 = "http://tempuri.org/";
 private static final String url2 = "http://10.0.2.2/checkhash/Service1.asmx"; 

String password="abc";
public final static int NO_OPTIONS = 0;
String hash;
    String result2;


@Override
public void onCreate(Bundle savedInstanceState) 
{
    super.onCreate(savedInstanceState);
    setContentView(R.layout.main);

    final EditText pass=(EditText)findViewById(R.id.editText1);
    Button encode=(Button)findViewById(R.id.button1);            
    encode.setOnClickListener(new View.OnClickListener() {
        public void onClick(View v)  {
            // Perform action on click
            password=pass.getText().toString();
            if(password!=null){
                try { 
        SHA1(password) ;
        } catch (UnsupportedEncodingException e) {                                          
                      e.printStackTrace();
        } catch (IOException e) {   
            e.printStackTrace();                    
                      }
            }
            else{
       Toast.makeText(PaswordencodingActivity.this, "this is a negative onClick", Toast.LENGTH_LONG).show();
            }

           }

          });


        }


private static String convertToHex(byte[] data) throws java.io.IOException 
 {
        System.out.println("data received is"  +data);

        StringBuffer sb = new StringBuffer();
        String hex=null;

        hex=Base64.encodeToString(data, 0, data.length, NO_OPTIONS);

        for (int i = 0; i < data.length; i++) 
        {            
            if (hex.length() == 1) 
            {
                sb.append('0');
            }
            sb.append(hex);
        }

       return sb.toString();
    }

public void SHA1(String text) throws IOException
{
    MessageDigest mdSha1 = null;
    try 
    {
      mdSha1 = MessageDigest.getInstance("SHA-1");
    } catch (NoSuchAlgorithmException e1) {
      Log.e("myapp", "Error initializing SHA1 message digest");
    }
    mdSha1.update(text.getBytes("iso-8859-1"), 0, text.length());
    byte[] data = mdSha1.digest();
    hash=convertToHex(data);

    System.out.println("data going is"  +data);
    System.out.println("hash value"+hash);

    try
    {
        result2=call3(password);
        if(result2.equalsIgnoreCase(hash.toString()))
        System.out.println("success");


    } catch (XmlPullParserException e)
    {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }   

        }

public String call3(String pass) throws XmlPullParserException
{
        String b=""; 

        SoapObject request = new SoapObject(namespace2, method_name);      
        request.addProperty("str",pass);

        SoapSerializationEnvelope envelope = new SoapSerializationEnvelope(SoapEnvelope.VER11); 
        envelope.dotNet = true; 
        envelope.setOutputSoapObject(request);

        HttpTransportSE  android = new HttpTransportSE(url2);

        android.debug = true; 
 try 
 {

        android.call(soap_action, envelope);

        SoapPrimitive result = (SoapPrimitive)envelope.getResponse();
        Log.i("myapp",result.toString());
        System.out.println(" --- response ---- " + result); 
        b=result.toString();


        } catch (SocketException ex) { 
            ex.printStackTrace(); 
        } catch (Exception e) { 
            e.printStackTrace(); 
        } 

        return b;   

}
}

Basically when I am trying to compare the two hash strings I am not getting the result

Why so ? can anyone help?

Logcat:

        11-25 17:09:50.899: INFO/System.out(275): data received is[B@44ef8eb0
        11-25 17:09:50.909: INFO/System.out(275): data going is[B@44ef8eb0
        11-25 17:09:50.909: INFO/System.out(275): hash valueUGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:09:50.909: INFO/System.out(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:10:01.730: INFO/myapp(275): UGGpBypVug3K+/4xONpqv9wkFd8=
        11-25 17:10:01.730: INFO/System.out(275):  --- response ---- UGGpBypVug3K+/4xONpqv9wkFd8=

peceps · Accepted Answer · 2011-11-25 13:21:23Z

1

Try

result2 = result2.trim();
hash = hash.trim();

System.out.println("result2='" + result2 + "'");
System.out.println("hash ='" + hash + "'");

if(result2.equalsIgnoreCase(hash))
   System.out.println("success");

If this does not help, check the actual arrays:

byte[] a = result.toString().getBytes() 
byte[] b = hash..getBytes();

If the arrays are not equal, you have strings in different encodings.

answered Nov 25, 2011 at 13:21

peceps

17.6k11 gold badges75 silver badges83 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Parth Doshi Over a year ago

fine both are not working tried them..now tell me how to change encoding on android side code..my .net web service is ASCII btw

Parth Doshi Over a year ago

I tried using both ASCII in my android app and server side code..still no proper result :(

Caner · Accepted Answer · 2011-11-25 13:21:22Z

1

I think you convert byte[] to String in wrong way, it should be like this:

hash = new String(data);

Also you are doing the comparison wrong, should be like this:

if(result2.equals(hash))

In my opinion you should not convert byte[] to String at all. Use Arrays.equals(byteArray1,byteArray2);. Your data is random bits of 1 and 0s. Converting it to String can be done in many ways, but it doesn't make any sense.

edited Nov 25, 2011 at 13:21

answered Nov 25, 2011 at 13:15

Caner

59.7k37 gold badges184 silver badges185 bronze badges

1 Comment

Parth Doshi Over a year ago

Sorry I didn't get ur first point of converting hash=new String(data); can u explain that ? Also, I tried using equals, equalsIgnoreCase and all possible methods for String comparison but still I don't get result as "success"

Che Jami · Accepted Answer · 2011-11-25 14:17:37Z

1

If you are applying the hashing algorithm on data derived from a String, you need to use the same character encoding to retrieve the bytes.

text.getBytes("iso-8859-1")

Different character sets can represent byte values differently.

edited Nov 25, 2011 at 14:17

answered Nov 25, 2011 at 13:50

Che Jami

5,1512 gold badges23 silver badges18 bronze badges

5 Comments

Parth Doshi Over a year ago

ok fine so in my server side i m using ASCII so in android side can i write text.getBytes("ASCII")

Parth Doshi Over a year ago

ok after doing that how do I compare? Should i compare using equalsIgnoreCase as @peceps has mentioned or compare byte arrays?

Parth Doshi Over a year ago

please see this : pastie.org/2919436 . Is this correct ? and will I get my output if I use String.equals now ?

Parth Doshi Over a year ago

but it's not working dude !! that's the problem..please help !!

Parth Doshi Over a year ago

let us continue this discussion in chat

Collectives™ on Stack Overflow

Compare two hash strings generated using SHA-1 in Android

3 Answers 3

2 Comments

1 Comment

5 Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

2 Comments

1 Comment

5 Comments

Your Answer

Sign up or log in

Post as a guest

Related