mirror of
https://github.com/RfidResearchGroup/proxmark3.git
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181 lines
5.7 KiB
C
181 lines
5.7 KiB
C
//-----------------------------------------------------------------------------
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// Copyright (C) Proxmark3 contributors. See AUTHORS.md for details.
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//
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// This program is free software: you can redistribute it and/or modify
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// it under the terms of the GNU General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// This program is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU General Public License for more details.
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//
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// See LICENSE.txt for the text of the license.
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//-----------------------------------------------------------------------------
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// Generic CRC calculation code.
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//-----------------------------------------------------------------------------
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// the Check value below in the comments is CRC of the string '123456789'
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//
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#include "crc.h"
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#include "commonutil.h"
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void crc_init_ref(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor, bool refin, bool refout) {
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crc_init(crc, order, polynom, initial_value, final_xor);
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crc->refin = refin;
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crc->refout = refout;
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crc_clear(crc);
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}
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void crc_init(crc_t *crc, int order, uint32_t polynom, uint32_t initial_value, uint32_t final_xor) {
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crc->order = order;
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crc->topbit = BITMASK(order - 1);
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crc->polynom = polynom;
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crc->initial_value = initial_value;
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crc->final_xor = final_xor;
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crc->mask = (1L << order) - 1;
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crc->refin = false;
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crc->refout = false;
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crc_clear(crc);
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}
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void crc_clear(crc_t *crc) {
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crc->state = crc->initial_value & crc->mask;
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if (crc->refin)
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crc->state = reflect(crc->state, crc->order);
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}
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void crc_update2(crc_t *crc, uint32_t data, int data_width) {
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if (crc->refin)
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data = reflect(data, data_width);
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// Bring the next byte into the remainder.
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crc->state ^= data << (crc->order - data_width);
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for (uint8_t bit = data_width; bit > 0; --bit) {
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if (crc->state & crc->topbit)
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crc->state = (crc->state << 1) ^ crc->polynom;
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else
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crc->state = (crc->state << 1);
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}
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}
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void crc_update(crc_t *crc, uint32_t data, int data_width) {
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if (crc->refin)
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data = reflect(data, data_width);
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int i;
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for (i = 0; i < data_width; i++) {
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int oldstate = crc->state;
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crc->state = crc->state >> 1;
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if ((oldstate ^ data) & 1) {
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crc->state ^= crc->polynom;
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}
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data >>= 1;
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}
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}
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uint32_t crc_finish(crc_t *crc) {
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uint32_t val = crc->state;
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if (crc->refout)
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val = reflect(val, crc->order);
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return (val ^ crc->final_xor) & crc->mask;
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}
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/*
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static void print_crc(crc_t *crc) {
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printf(" Order %d\n Poly %x\n Init %x\n Final %x\n Mask %x\n topbit %x\n RefIn %s\n RefOut %s\n State %x\n",
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crc->order,
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crc->polynom,
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crc->initial_value,
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crc->final_xor,
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crc->mask,
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crc->topbit,
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(crc->refin) ? "TRUE":"FALSE",
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(crc->refout) ? "TRUE":"FALSE",
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crc->state
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);
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}
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*/
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// width=8 poly=0x31 init=0x00 refin=true refout=true xorout=0x00 check=0xA1 name="CRC-8/MAXIM"
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uint32_t CRC8Maxim(uint8_t *buff, size_t size) {
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crc_t crc;
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crc_init_ref(&crc, 8, 0x31, 0, 0, true, true);
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for (size_t i = 0; i < size; ++i) {
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crc_update2(&crc, buff[i], 8);
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}
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return crc_finish(&crc);
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}
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// width=8 poly=0x1d, init=0xc7 (0xe3 - WRONG! but it mentioned in MAD datasheet) refin=false refout=false xorout=0x00 name="CRC-8/MIFARE-MAD"
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uint32_t CRC8Mad(uint8_t *buff, size_t size) {
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crc_t crc;
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crc_init_ref(&crc, 8, 0x1d, 0xc7, 0, false, false);
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for (size_t i = 0; i < size; ++i) {
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crc_update2(&crc, buff[i], 8);
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}
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return crc_finish(&crc);
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}
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// width=4 poly=0xC, reversed poly=0x7 init=0x5 refin=true refout=true xorout=0x0000 check= name="CRC-4/LEGIC"
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uint32_t CRC4Legic(uint8_t *buff, size_t size) {
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crc_t crc;
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crc_init_ref(&crc, 4, 0x19 >> 1, 0x5, 0, true, true);
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crc_update2(&crc, 1, 1); /* CMD_READ */
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crc_update2(&crc, buff[0], 8);
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crc_update2(&crc, buff[1], 8);
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return reflect(crc_finish(&crc), 4);
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}
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// width=8 poly=0x63, reversed poly=0x8D init=0x55 refin=true refout=true xorout=0x0000 check=0xC6 name="CRC-8/LEGIC"
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// the CRC needs to be reversed before returned.
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uint32_t CRC8Legic(uint8_t *buff, size_t size) {
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crc_t crc;
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crc_init_ref(&crc, 8, 0x63, 0x55, 0, true, true);
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for (size_t i = 0; i < size; ++i) {
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crc_update2(&crc, buff[i], 8);
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}
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return reflect8(crc_finish(&crc));
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}
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// width=8 poly=0x7, init=0x2C refin=false refout=false xorout=0x0000 check=0 name="CRC-8/CARDX"
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uint32_t CRC8Cardx(uint8_t *buff, size_t size) {
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crc_t crc;
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crc_init_ref(&crc, 8, 0x7, 0x2C, 0, false, false);
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for (size_t i = 0; i < size; ++i) {
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crc_update2(&crc, buff[i], 8);
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}
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return crc_finish(&crc);
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}
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uint32_t CRC8Hitag1(uint8_t *buff, size_t size) {
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crc_t crc;
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crc_init_ref(&crc, 8, 0x1d, 0xff, 0, false, false);
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for (size_t i = 0; i < size; i++) {
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crc_update2(&crc, buff[i], 8);
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}
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return crc_finish(&crc);
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}
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uint32_t CRC8Hitag1Bits(const uint8_t *buff, size_t bitsize) {
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crc_t crc;
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uint8_t data = 0;
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uint8_t n = 0;
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crc_init_ref(&crc, 8, 0x1d, 0xff, 0, false, false);
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size_t i;
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for (i = 0; i < bitsize; i++) {
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data <<= 1;
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data += (buff[i / 8] >> (7 - (i % 8))) & 1;
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n += 1;
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if (n == 8) {
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crc_update2(&crc, data, n);
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n = 0;
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data = 0;
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}
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}
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if (n > 0) {
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crc_update2(&crc, data, n);
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}
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return crc_finish(&crc);
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}
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