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proxmark3/common/crc16.c
iceman1001 01b149efa5 fix: fdx crc calc
2019-10-30 15:44:57 +01:00

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9.1 KiB
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//-----------------------------------------------------------------------------
// This code is licensed to you under the terms of the GNU GPL, version 2 or,
// at your option, any later version. See the LICENSE.txt file for the text of
// the license.
//-----------------------------------------------------------------------------
// CRC16
//-----------------------------------------------------------------------------
#include "crc16.h"
#include <string.h>
#include "commonutil.h"
static uint16_t crc_table[256];
static bool crc_table_init = false;
static CrcType_t current_crc_type = CRC_NONE;
void init_table(CrcType_t crctype) {
// same crc algo, and initialised already
if (crctype == current_crc_type && crc_table_init)
return;
// not the same crc algo. reset table.
if (crctype != current_crc_type)
reset_table();
current_crc_type = crctype;
switch (crctype) {
case CRC_14443_A:
case CRC_14443_B:
case CRC_15693:
case CRC_ICLASS:
generate_table(CRC16_POLY_CCITT, true);
break;
case CRC_FELICA:
case CRC_XMODEM:
generate_table(CRC16_POLY_CCITT, false);
break;
case CRC_LEGIC:
generate_table(CRC16_POLY_LEGIC, true);
break;
case CRC_CCITT:
generate_table(CRC16_POLY_CCITT, false);
break;
case CRC_KERMIT:
generate_table(CRC16_POLY_CCITT, true);
break;
case CRC_11784:
generate_table(CRC16_POLY_CCITT, false);
break;
case CRC_NONE:
crc_table_init = false;
current_crc_type = CRC_NONE;
break;
}
}
void generate_table(uint16_t polynomial, bool refin) {
for (uint16_t i = 0; i < 256; i++) {
uint16_t c, crc = 0;
if (refin)
c = reflect8(i) << 8;
else
c = i << 8;
for (uint16_t j = 0; j < 8; j++) {
if ((crc ^ c) & 0x8000)
crc = (crc << 1) ^ polynomial;
else
crc = crc << 1;
c = c << 1;
}
if (refin)
crc = reflect16(crc);
crc_table[i] = crc;
}
crc_table_init = true;
}
void reset_table(void) {
memset(crc_table, 0, sizeof(crc_table));
crc_table_init = false;
current_crc_type = CRC_NONE;
}
// table lookup LUT solution
uint16_t crc16_fast(uint8_t const *d, size_t n, uint16_t initval, bool refin, bool refout) {
// fast lookup table algorithm without augmented zero bytes, e.g. used in pkzip.
// only usable with polynom orders of 8, 16, 24 or 32.
if (n == 0)
return (~initval);
uint16_t crc = initval;
if (refin)
crc = reflect16(crc);
if (!refin)
while (n--) crc = (crc << 8) ^ crc_table[((crc >> 8) ^ *d++) & 0xFF ];
else
while (n--) crc = (crc >> 8) ^ crc_table[(crc & 0xFF) ^ *d++];
if (refout ^ refin)
crc = reflect16(crc);
return crc;
}
// bit looped solution TODO REMOVED
uint16_t update_crc16_ex(uint16_t crc, uint8_t c, uint16_t polynomial) {
uint16_t tmp = 0;
uint16_t v = (crc ^ c) & 0xff;
for (uint16_t i = 0; i < 8; i++) {
if ((tmp ^ v) & 1)
tmp = (tmp >> 1) ^ polynomial;
else
tmp >>= 1;
v >>= 1;
}
return ((crc >> 8) ^ tmp) & 0xffff;
}
uint16_t update_crc16(uint16_t crc, uint8_t c) {
return update_crc16_ex(crc, c, CRC16_POLY_CCITT);
}
// two ways. msb or lsb loop.
uint16_t Crc16(uint8_t const *d, size_t length, uint16_t remainder, uint16_t polynomial, bool refin, bool refout) {
if (length == 0)
return (~remainder);
for (uint32_t i = 0; i < length; ++i) {
uint8_t c = d[i];
if (refin) c = reflect8(c);
// xor in at msb
remainder ^= (c << 8);
// 8 iteration loop
for (uint8_t j = 8; j; --j) {
if (remainder & 0x8000) {
remainder = (remainder << 1) ^ polynomial;
} else {
remainder <<= 1;
}
}
}
if (refout)
remainder = reflect16(remainder);
return remainder;
}
void compute_crc(CrcType_t ct, const uint8_t *d, size_t n, uint8_t *first, uint8_t *second) {
// can't calc a crc on less than 1 byte
if (n == 0) return;
init_table(ct);
uint16_t crc = 0;
switch (ct) {
case CRC_14443_A:
crc = crc16_a(d, n);
break;
case CRC_14443_B:
case CRC_15693:
crc = crc16_x25(d, n);
break;
case CRC_ICLASS:
crc = crc16_iclass(d, n);
break;
case CRC_FELICA:
case CRC_XMODEM:
crc = crc16_xmodem(d, n);
break;
case CRC_CCITT:
crc = crc16_ccitt(d, n);
break;
case CRC_KERMIT:
crc = crc16_kermit(d, n);
break;
case CRC_11784:
crc = crc16_fdx(d, n);
break;
case CRC_LEGIC:
// TODO
return;
case CRC_NONE:
return;
}
*first = (crc & 0xFF);
*second = ((crc >> 8) & 0xFF);
}
uint16_t Crc16ex(CrcType_t ct, const uint8_t *d, size_t n) {
// can't calc a crc on less than 3 byte. (1byte + 2 crc bytes)
if (n < 3) return 0;
init_table(ct);
switch (ct) {
case CRC_14443_A:
return crc16_a(d, n);
case CRC_14443_B:
case CRC_15693:
return crc16_x25(d, n);
case CRC_ICLASS:
return crc16_iclass(d, n);
case CRC_FELICA:
case CRC_XMODEM:
return crc16_xmodem(d, n);
case CRC_CCITT:
return crc16_ccitt(d, n);
case CRC_KERMIT:
return crc16_kermit(d, n);
case CRC_11784:
return crc16_fdx(d, n);
case CRC_LEGIC:
// TODO
return 0;
case CRC_NONE:
default:
break;
}
return 0;
}
// check CRC
// ct crc type
// d buffer with data
// n length (including crc)
//
// This function uses the message + crc bytes in order to compare the "residue" afterwards.
// crc16 algos like CRC-A become 0x0000
// while CRC-15693 become 0x0F47
// If calculated with crc bytes, the residue should be 0xF0B8
bool check_crc(CrcType_t ct, const uint8_t *d, size_t n) {
// can't calc a crc on less than 3 byte. (1byte + 2 crc bytes)
if (n < 3) return false;
init_table(ct);
switch (ct) {
case CRC_14443_A:
return (crc16_a(d, n) == 0);
case CRC_14443_B:
return (crc16_x25(d, n) == X25_CRC_CHECK);
case CRC_15693:
return (crc16_x25(d, n) == X25_CRC_CHECK);
case CRC_ICLASS:
return (crc16_iclass(d, n) == 0);
case CRC_FELICA:
case CRC_XMODEM:
return (crc16_xmodem(d, n) == 0);
case CRC_CCITT:
return (crc16_ccitt(d, n) == 0);
case CRC_KERMIT:
return (crc16_kermit(d, n) == 0);
case CRC_11784:
return (crc16_fdx(d, n) == 0);
case CRC_LEGIC:
// TODO
return false;
case CRC_NONE:
default:
break;
}
return false;
}
// poly=0x1021 init=0xffff refin=false refout=false xorout=0x0000 check=0x29b1 residue=0x0000 name="CRC-16/CCITT-FALSE"
uint16_t crc16_ccitt(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0xffff, false, false);
}
// FDX-B ISO11784/85) uses KERMIT/CCITT
// poly 0x xx init=0x000 refin=false refout=true xorout=0x0000 ...
uint16_t crc16_fdx(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0x0000, false, true);
}
// poly=0x1021 init=0x0000 refin=true refout=true xorout=0x0000 name="KERMIT"
uint16_t crc16_kermit(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0x0000, true, true);
}
// FeliCa uses XMODEM
// poly=0x1021 init=0x0000 refin=false refout=false xorout=0x0000 name="XMODEM"
uint16_t crc16_xmodem(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0x0000, false, false);
}
// Following standards uses X-25
// ISO 15693,
// ISO 14443 CRC-B
// ISO/IEC 13239 (formerly ISO/IEC 3309)
// poly=0x1021 init=0xffff refin=true refout=true xorout=0xffff name="X-25"
uint16_t crc16_x25(uint8_t const *d, size_t n) {
uint16_t crc = crc16_fast(d, n, 0xffff, true, true);
crc = ~crc;
return crc;
}
// CRC-A (14443-3)
// poly=0x1021 init=0xc6c6 refin=true refout=true xorout=0x0000 name="CRC-A"
uint16_t crc16_a(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0xC6C6, true, true);
}
// iClass crc
// initvalue 0x4807 reflected 0xE012
// poly 0x1021 reflected 0x8408
// poly=0x1021 init=0x4807 refin=true refout=true xorout=0x0BC3 check=0xF0B8 name="CRC-16/ICLASS"
uint16_t crc16_iclass(uint8_t const *d, size_t n) {
return crc16_fast(d, n, 0x4807, true, true);
}
// This CRC-16 is used in Legic Advant systems.
// poly=0xB400, init=depends refin=true refout=true xorout=0x0000 check= name="CRC-16/LEGIC"
uint16_t crc16_legic(uint8_t const *d, size_t n, uint8_t uidcrc) {
uint16_t initial = uidcrc << 8 | uidcrc;
return crc16_fast(d, n, initial, true, true);
}
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