Fix MAD CRC algorithm.
The CRC algorithm is not a standard CRC algorithm so rename it to nxp_crc() and adjust all related code.
This commit is contained in:
Romain Tartiere
parent
42692ccf54
commit
feb240ee73
3 changed files with 110 additions and 136 deletions
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@ -39,7 +39,7 @@
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struct mad_sector_0x00;
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struct mad_sector_0x10;
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void crc8 (uint8_t *crc, const uint8_t value);
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void nxp_crc (uint8_t *crc, const uint8_t value);
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MifareTag mifare_classic_tag_new (void);
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void mifare_classic_tag_free (MifareTag tag);
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MifareTag mifare_ultralight_tag_new (void);
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@ -38,15 +38,10 @@
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#include "freefare_internal.h"
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/*
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* XXX The documentation says the preset is 0xE3, but the various card dumps
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* and the documentation example MAD CRC can be verified only with a CRC
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* preset of 0x67.
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*
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* This is still under investigation:
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* http://www.libnfc.org/community/post/667/
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* http://discussion.forum.nokia.com/forum/showthread.php?t=181702#14
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* The documentation says the preset is 0xE3 but the bits have to be mirrored:
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* 0xe3 = 1110 0011 <=> 1100 0111 = 0xc7
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*/
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#define CRC_PRESET 0x67
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#define CRC_PRESET 0xc7
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#define SECTOR_0X00_AIDS 15
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#define SECTOR_0X10_AIDS 23
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@ -96,15 +91,15 @@ mad_new (uint8_t version)
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* Compute CRC.
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*/
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void
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crc8 (uint8_t *crc, const uint8_t value)
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nxp_crc (uint8_t *crc, const uint8_t value)
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{
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/* x^8 + x^4 + x^3 + x^2 + 1 => 0x11d */
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const uint8_t poly = 0x1d;
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*crc ^= value;
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for (int current_bit = 7; current_bit >= 0; current_bit--) {
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int bit_out = (*crc) & 0x80;
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*crc = ((*crc) << 1) | (( value >> (current_bit)) & 0x01);
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*crc <<= 1;
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if (bit_out)
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*crc ^= poly;
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@ -116,13 +111,12 @@ sector_0x00_crc8 (Mad mad)
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{
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uint8_t crc = CRC_PRESET;
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crc8 (&crc, mad->sector_0x00.info);
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nxp_crc (&crc, mad->sector_0x00.info);
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for (int n = 0; n < SECTOR_0X00_AIDS; n++) {
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crc8 (&crc, mad->sector_0x00.aids[n].application_code);
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crc8 (&crc, mad->sector_0x00.aids[n].function_cluster_code);
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nxp_crc (&crc, mad->sector_0x00.aids[n].application_code);
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nxp_crc (&crc, mad->sector_0x00.aids[n].function_cluster_code);
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}
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crc8 (&crc, 0x00);
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return crc;
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}
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@ -132,13 +126,12 @@ sector_0x10_crc8 (Mad mad)
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{
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uint8_t crc = CRC_PRESET;
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crc8 (&crc, mad->sector_0x10.info);
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nxp_crc (&crc, mad->sector_0x10.info);
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for (int n = 0; n < SECTOR_0X10_AIDS; n++) {
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crc8 (&crc, mad->sector_0x10.aids[n].application_code);
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crc8 (&crc, mad->sector_0x10.aids[n].function_cluster_code);
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nxp_crc (&crc, mad->sector_0x10.aids[n].application_code);
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nxp_crc (&crc, mad->sector_0x10.aids[n].function_cluster_code);
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}
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crc8 (&crc, 0x00);
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return crc;
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}
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213
test/test_mad.c
213
test/test_mad.c
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@ -67,7 +67,7 @@ test_mad (void)
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mad_free (mad);
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}
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#define CRC_PRESET 0x67
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#define CRC_PRESET 0xc7
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void
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test_mad_crc8_basic (void)
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@ -75,30 +75,14 @@ test_mad_crc8_basic (void)
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uint8_t crc;
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const uint8_t crc_value = 0x42;
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/* Insert data */
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crc = 0x00;
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crc8(&crc, crc_value);
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cut_assert_equal_int (crc_value, crc, cut_message ("Initialization should not produce a CRC"));
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/* Insert data with leading zeros */
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crc = 0x00;
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, crc_value);
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cut_assert_equal_int (crc_value, crc, cut_message ("Burst error should not be detected with uninitialized polies"));
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/* Check integrity */
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crc = CRC_PRESET;
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crc8(&crc, crc_value);
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crc8(&crc, 0x00);
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nxp_crc(&crc, crc_value);
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uint8_t save = crc;
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crc = CRC_PRESET;
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crc8(&crc, crc_value);
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crc8(&crc, save);
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nxp_crc(&crc, crc_value);
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nxp_crc(&crc, save);
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cut_assert_equal_int (0x00, crc, cut_message ("CRC should verify crc(message + crc(message)) = 0"));
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}
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@ -112,46 +96,45 @@ test_mad_crc8_doc_example (void)
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uint8_t crc = CRC_PRESET;
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/* Block 1 -- 0x01 - 0x07 */
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crc8(&crc, 0x01);
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crc8(&crc, 0x01);
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crc8(&crc, 0x08);
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crc8(&crc, 0x01);
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crc8(&crc, 0x08);
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crc8(&crc, 0x01);
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crc8(&crc, 0x08);
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nxp_crc(&crc, 0x01);
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nxp_crc(&crc, 0x01);
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nxp_crc(&crc, 0x08);
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nxp_crc(&crc, 0x01);
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nxp_crc(&crc, 0x08);
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nxp_crc(&crc, 0x01);
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nxp_crc(&crc, 0x08);
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/* Block 2 -- 0x08 - 0x0f */
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x04);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x04);
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nxp_crc(&crc, 0x00);
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/* Block 3 -- 0x00 - 0x07 */
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crc8(&crc, 0x03);
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crc8(&crc, 0x10);
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crc8(&crc, 0x03);
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crc8(&crc, 0x10);
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crc8(&crc, 0x02);
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crc8(&crc, 0x10);
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crc8(&crc, 0x02);
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crc8(&crc, 0x10);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0x10);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0x10);
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nxp_crc(&crc, 0x02);
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nxp_crc(&crc, 0x10);
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nxp_crc(&crc, 0x02);
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nxp_crc(&crc, 0x10);
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/* Block 3 -- 0x08 - 0x0f */
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x11);
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crc8(&crc, 0x30);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x11);
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nxp_crc(&crc, 0x30);
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/* Append zeros of augmented message */
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crc8(&crc, 0x00);
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cut_assert_equal_int (0x89, crc, cut_message ("Sample CRC should match"));
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}
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@ -166,46 +149,45 @@ test_mad_crc8_real_example_1 (void)
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uint8_t crc = CRC_PRESET;
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/* Block 1 -- 0x01 - 0x07 */
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crc8(&crc, 0x01);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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nxp_crc(&crc, 0x01);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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/* Block 2 -- 0x08 - 0x0f */
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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/* Block 3 -- 0x00 - 0x07 */
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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/* Block 3 -- 0x08 - 0x0f */
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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/* Append zeros of augmented message */
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crc8(&crc, 0x00);
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cut_assert_equal_int (0xc4, crc, cut_message ("Read example 1 CRC should match"));
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}
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@ -220,46 +202,45 @@ test_mad_crc8_real_example_2 (void)
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uint8_t crc = CRC_PRESET;
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/* Block 1 -- 0x01 - 0x07 */
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crc8(&crc, 0x01);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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nxp_crc(&crc, 0x01);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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/* Block 2 -- 0x08 - 0x0f */
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x03);
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crc8(&crc, 0xe1);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x03);
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nxp_crc(&crc, 0xe1);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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/* Block 3 -- 0x00 - 0x07 */
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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/* Block 3 -- 0x08 - 0x0f */
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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crc8(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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nxp_crc(&crc, 0x00);
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/* Append zeros of augmented message */
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crc8(&crc, 0x00);
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cut_assert_equal_int (0xab, crc, cut_message ("Read example 1 CRC should match"));
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}
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