mifare classic AuthenticateKeyNo() getting a error "Reference key not useable"

Question

I'm using a mifare classic 4k card. I try to write text in the second block of the card. When I try the function AuthenticateKeyNo(1, 1, MifareKeyType.KT_KEY_A), it gives me the following error:

"Reference key not useable"

This is my code:

public void WriteData()
    {
       IReaderUnit reader = null;
       var readerProvider = new PCSCReaderProvider();

       IEnumerable readerList = readerProvider.GetReaderList();
       IEnumerable found = (IEnumerable)readerProvider.WaitForReaders(new string[] { "SCM Microsystems Inc. SCL010 Contactless Reader 0" }, 1, true);
       foreach (IReaderUnit item in found.OfType<IReaderUnit>())
            reader = item;

            if (reader.WaitInsertion(30000))
               {
                 if (reader.Connect())
                   {
                      chip chip = reader.GetSingleChip();
                      if (chip is MifareChip)
                       {
                         IMifareCommands cmd = chip.Commands as IMifareCommands;

                         MifareKey key = new MifareKey();
                         key.Value = "ff ff ff ff ff ff";

                         cmd.LoadKeyNo(1, key, MifareKeyType.KT_KEY_A);
                         cmd.AuthenticateKeyNo(1, 1, MifareKeyType.KT_KEY_A);
                         cmd.WriteBinary(1, "test");
                       }

                   }
               }
     }

I use liblogicalaccess.com dll

Can anybody explain me what is wrong with my code?

Answer 1

It might be an issue, because you are providing String value as a Key. Keys are ussually Byte-arrays (0xFF, 0xFF,..).

In the GitHub project of the Library you used, I could see in the example they used fromString("FF FF .. FF") so fromString might be converting the String into something else (probably byte-array or Hex values).

Answer 2

can you read block 3 of your card? By transport configuration you should really use key A for login, but it is also possible that by access bits combination you should login with KeyB only, not KeyA, like MifareKeyType.KT_KEY_B. Or, if you would post block 3 data - it would be really easier. Also, check pls under debug which bytes you send exactly. So, for "FFFFFFFFFFFF" it should be like: 255 255 255 255 255 255