JavaCard OS

Posted: **Mon Oct 17, 2016 11:14 pm**

I tried to use MessageDigest to get hash. it always returned 6F 00. I guess MessageDigest.getInstance caused the problem, but I'm not sure. ANY HELP? tHANKS!

My sectional code:

Code: Select all

private void getDigest(byte[] buffer)
     {
          if (hashArray == null)
               hashArray = JCSystem.makeTransientByteArray((short)20, JCSystem.CLEAR_ON_DESELECT);
                    
          MessageDigest alg = MessageDigest.getInstance(MessageDigest.ALG_SHA,true);// If I comment this line, the applet can run w/o any problem.
                    
     }

Posted: **Tue Oct 18, 2016 3:39 am**

Use try/catch to find the reason.

Just like:

Code: Select all

try{
   MessageDigest alg = MessageDigest.getInstance(MessageDigest.ALG_SHA,true);
    }
catch(CryptoException e)
   {
     if ( e.GetReason() == CryptoException.NO_SUCH_ALGORITHM )
                           ISOException.throwIt( something );
   }

Posted: **Tue Oct 18, 2016 4:46 am**

MessageDigest.getInstance exception:

Throws:
CryptoException - with the following reason codes:
CryptoException.NO_SUCH_ALGORITHM if the requested algorithm or shared access mode is not supported.

So, you should make sure that that your card supports SHA.

JavaCard OS

How to get hash of message

How to get hash of message

Re: How to get hash of message

Re: How to get hash of message