Cannot authenticate NTAG213 - nfc

Question

I am using an ACR122U NFC reader to password protect an NTAG213 NFC label. I think I have managed to set the password correctly, but I cannot authenticate and change the label afterward. My code for authenticating looks like this:
#include <winscard.h>
#include <iostream>
#pragma comment(lib, "winscard.lib")
const char *ReaderName = "ACS ACR122 0";
unsigned Password = 0x12345678;
int main()
{
//Establish context
SCARDCONTEXT hContext;
DWORD SCard_Status1 = SCardEstablishContext(SCARD_SCOPE_USER, NULL, NULL, &hContext);
if(SCard_Status1 != SCARD_S_SUCCESS)
return 1;
//connect to the card
SCARDHANDLE hCardHandle;
DWORD Protocol;
DWORD SCard_Status2 = SCardConnect(hContext, ReaderName, SCARD_SHARE_SHARED, SCARD_PROTOCOL_T1, &hCardHandle, &Protocol);
if(SCard_Status2 != SCARD_S_SUCCESS)
{
SCardReleaseContext(hContext);
return 1;
}
SCARD_IO_REQUEST Request;
Request.dwProtocol = Protocol;
Request.cbPciLength = sizeof(SCARD_IO_REQUEST);
BYTE TxData[] =
{
0xFF, //CLA
0x00, //INS
0x00, //P1
0x00, //P2
0x08, //LC
0xD4,
0x40,
0x01,
0x1B, //PWD_AUTH (See data sheet)
Password,
Password >> 8,
Password >> 16,
Password >> 24,
};
BYTE RxData[254];
unsigned long RxLength = sizeof(RxData);
DWORD SCard_Status3 = SCardTransmit(hCardHandle, &Request, TxData, sizeof(TxData), NULL, RxData, &RxLength);
std::cout << "SCard_Status = " << SCard_Status3 << std::endl;
std::cout << "RxLength = " << RxLength << std::endl;
SCardDisconnect(hCardHandle, SCARD_EJECT_CARD);
SCardReleaseContext(hContext);
return 0;
}
This should send the PWD_AUTH command to the NTAG213 with the Pwd. I expected to receive an error if the password is wrong or two bytes with the PACK if the password is correct. But SCard_Status is SCARD_S_SUCCESS and RxLength is 0 afterwards. And if I try to write to the label I get an error.
I am having trouble finding any examples showing how to do this. Can anyone see what I am doing wrong?

Answer 1

I am going to answer this myself. I managed to make it work by changing TxData to this:
BYTE TxData[] =
{
0xFF, //CLA
0x00, //INS
0x00, //P1
0x00, //P2
0x07, //LC
0xD4, 0x42, //InCommunicateThru
0x1B, //PWD_AUTH (See data sheet)
Password,
Password >> 8,
Password >> 16,
Password >> 24,
};
I found the command InCommunicateThru (D4 42) as a replacement for InDataExchange (D4 40) in the data sheet for the PN532, which is the NFC processor inside the ACR122U.