Smart Card development- Class not supported error

Question

I am developing application for smart cards using ISO/IEC 7816-4 standard. I sucessfully finished Applet Selection (it uses class 00), but when trying PIN verification (it uses class 88), I encountered 6E 00 respond, which corresponds to Class not supported error.

I have this requirements:

IsoCase: Case3Short Class: 0x88 Instruction: 0x11 P1-P2: 0x0400 Command Length (Lc): 0x04 Command Data: 4 bytes where each represents one PIN digit Expected Length (Le): 0

Here is the link for documentation: https://www.gnupg.org/ftp/specs/openpgp-card-2.1.pdf

This is the code I used, do you know what could be a possible problem and what I should change?

`

using System;
using PCSC;
using PCSC.Iso7816;

class Program
{
static void Main()
{
var contextFactory = ContextFactory.Instance;
using (var context = contextFactory.Establish(SCardScope.System))
{
Console.WriteLine("Currently connected readers: ");
var readerNames = context.GetReaders();
foreach (var readerName in readerNames)
{
Console.WriteLine("\\t" + readerName);
}

            using (var isoReader = new IsoReader(context, "Gemplus USB SmartCard Reader 0",                                        SCardShareMode.Shared, SCardProtocol.Any, false))
            {
                // Replace '2346' with the actual PIN you want to verify
                var pinToVerify = new byte[] { 0x01, 0x02, 0x03, 0x04 };
    
                // APDU command for PIN verification
                var apduCommand = new CommandApdu(IsoCase.Case3Short, isoReader.ActiveProtocol)
                {
                    CLA = 0x88,
                    INS = 0x11,
                    P1 = 0x04,
                    P2 = 0x00,
                    Data = pinToVerify
                };
    
                // Send the APDU command
                var response = isoReader.Transmit(apduCommand);
    
                // Check the response status word
                if (response.SW1 == 0x90 && response.SW2 == 0x00)
                {
                    Console.WriteLine("PIN verification successful!");
                }
                else if (response.SW1 == 0x63 && response.SW2 == 0x02)
                {
                    Console.WriteLine("Wrong PIN. Error response: 0x6302");
                }
                else
                {
                    Console.WriteLine($"PIN verification failed. Unexpected response: {response}");
                    Console.WriteLine("SW1 SW2 = {0:X2} {1:X2}", response.SW1, response.SW2);
                }
            }
        }
    }

}\

`

Answer 1

While you are stating, that the card conforms to ISO 7816-4, your given details seriously mismatch. For an ISO 7816-4 compliant Verify, class byte has to be zero and ins=0x20. Odd values for instruction byte are very seldom encountered except for some special cases as Read Binary and Generate Asymmetric Key Pair. The low-nibble bit 8 would typically indicate secure messaging, but your code does not perform the necessary processing for it. Specifying an LE byte is wrong for commands, which never return a result such as Verify.