code:     private void testModified()
          throws Exception
      {
          KeyFactory kFact = KeyFactory.getInstance("DSA", "BC");
          PublicKey pubKey = kFact.generatePublic(PUBLIC_KEY);
          Signature sig = Signature.getInstance("DSA", "BC");
  
          for (int i = 0; i != MODIFIED_SIGNATURES.length; i++)
          {
              sig.initVerify(pubKey);
  
              sig.update(Strings.toByteArray("Hello"));
  
              boolean failed;
  
              try
              {
                  failed = !sig.verify(Hex.decode(MODIFIED_SIGNATURES[i]));
              }
              catch (SignatureException e)
              {
                  failed = true;
              }
  
              isTrue("sig verified when shouldn't", failed);
          }
      }
  
  