libnfc/libnfc/iso14443-subr.c

122 lines
2.8 KiB
C

/*-
* Public platform independent Near Field Communication (NFC) library
*
* Copyright (C) 2009, Roel Verdult
*
* This program is free software: you can redistribute it and/or modify it
* under the terms of the GNU Lesser General Public License as published by the
* Free Software Foundation, either version 3 of the License, or (at your
* option) any later version.
*
* This program is distributed in the hope that it will be useful, but WITHOUT
* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
* FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
* more details.
*
* You should have received a copy of the GNU Lesser General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>
*/
/**
* @file iso14443-subr.c
* @brief Defines some function extracted for ISO/IEC 14443
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif // HAVE_CONFIG_H
#include <stdio.h>
#include <string.h>
#include <nfc/nfc.h>
#include "nfc-internal.h"
/**
* @brief CRC
*
*/
void
iso14443a_crc (uint8_t *pbtData, size_t szLen, uint8_t *pbtCrc)
{
uint8_t bt;
uint32_t wCrc = 0x6363;
do {
bt = *pbtData++;
bt = (bt ^ (uint8_t) (wCrc & 0x00FF));
bt = (bt ^ (bt << 4));
wCrc = (wCrc >> 8) ^ ((uint32_t) bt << 8) ^ ((uint32_t) bt << 3) ^ ((uint32_t) bt >> 4);
} while (--szLen);
*pbtCrc++ = (uint8_t) (wCrc & 0xFF);
*pbtCrc = (uint8_t) ((wCrc >> 8) & 0xFF);
}
/**
* @brief Append CRC
*
*/
void
iso14443a_crc_append (uint8_t *pbtData, size_t szLen)
{
iso14443a_crc (pbtData, szLen, pbtData + szLen);
}
/**
* @brief Locate historical bytes
* @see ISO/IEC 14443-4 (5.2.7 Historical bytes)
*/
uint8_t *
iso14443a_locate_historical_bytes (uint8_t *pbtAts, size_t szAts, size_t *pszTk)
{
if (szAts) {
size_t offset = 1;
if (pbtAts[0] & 0x10) { // TA
offset++;
}
if (pbtAts[0] & 0x20) { // TB
offset++;
}
if (pbtAts[0] & 0x40) { // TC
offset++;
}
if (szAts > offset) {
*pszTk = (szAts - offset);
return (pbtAts + offset);
}
}
*pszTk = 0;
return NULL;
}
/**
* @brief Add cascade tags (0x88) in UID
* @see ISO/IEC 14443-3 (6.4.4 UID contents and cascade levels)
*/
void
iso14443_cascade_uid (const uint8_t abtUID[], const size_t szUID, uint8_t *pbtCascadedUID, size_t *pszCascadedUID)
{
switch (szUID) {
case 7:
pbtCascadedUID[0] = 0x88;
memcpy (pbtCascadedUID + 1, abtUID, 7);
*pszCascadedUID = 8;
break;
case 10:
pbtCascadedUID[0] = 0x88;
memcpy (pbtCascadedUID + 1, abtUID, 3);
pbtCascadedUID[4] = 0x88;
memcpy (pbtCascadedUID + 5, abtUID + 3, 7);
*pszCascadedUID = 12;
break;
case 4:
default:
memcpy (pbtCascadedUID, abtUID, szUID);
*pszCascadedUID = szUID;
break;
}
}