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Initial implementation of encoding

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This commit is contained in:
DarkMatterMatt 2021-02-11 00:17:48 +13:00
parent ebd0c193f1
commit f655391bd4
1 changed files with 100 additions and 8 deletions
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108
client/src/cmdlfgallagher.c
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@ -29,7 +29,6 @@
static int CmdHelp(const char *Cmd);
/*
static void scramble(uint8_t *arr, uint8_t len) {
uint8_t lut[] = {
0xa3, 0xb0, 0x80, 0xc6, 0xb2, 0xf4, 0x5c, 0x6c, 0x81, 0xf1, 0xbb, 0xeb, 0x55, 0x67, 0x3c, 0x05,
@ -54,7 +53,6 @@ static void scramble(uint8_t *arr, uint8_t len) {
arr[i] = lut[arr[i]];
}
}
*/
static void descramble(uint8_t *arr, uint8_t len) {
uint8_t lut[] = {
@ -189,6 +187,45 @@ static int CmdGallagherReader(const char *Cmd) {
return PM3_SUCCESS;
}
static void createBlocks(uint32_t *blocks, uint8_t rc, uint16_t fc, uint32_t cn, uint8_t il) {
// put data into the correct places (Gallagher obfuscation)
uint8_t arr[8] = {0};
arr[0] = (cn & 0xffffff) >> 16;
arr[1] = (fc & 0xfff) >> 4;
arr[2] = (cn & 0x7ff) >> 3;
arr[3] = (cn & 0x7) << 5 | (rc & 0xf) << 1;
arr[4] = (cn & 0xffff) >> 11;
arr[5] = (fc & 0xffff) >> 12;
arr[6] = 0;
arr[7] = (fc & 0xf) << 4 | (il & 0xf);
// more obfuscation
scramble(arr, ARRAYLEN(arr));
// every byte has a 9th bit which is the inverse of the last bit
uint8_t bonus_bit[8] = {0};
for (int i = 0; i < 8; i++) {
bonus_bit[i] = !(arr[i] & 0x1);
}
// calculate checksum
uint8_t crc = CRC8Cardx(arr, ARRAYLEN(arr));
// magic prefix, then the 9-bit bytes, then the CRC
blocks[0] = (0x7fea << 16)
| (arr[0] << 8) | (bonus_bit[0] << 7)
| (arr[1] >> 1);
blocks[1] = ((arr[1] & 0x1) << 31) | (bonus_bit[1] << 30)
| (arr[2] << 22) | (bonus_bit[2] << 21)
| (arr[3] << 13) | (bonus_bit[3] << 12)
| (arr[4] << 4) | (bonus_bit[4] << 3)
| (arr[5] >> 5);
blocks[2] = ((arr[5] & 0x1f) << 27) | (bonus_bit[5] << 26)
| (arr[6] << 18) | (bonus_bit[6] << 17)
| (arr[7] << 9) | (bonus_bit[7] << 8)
| crc;
}
static int CmdGallagherClone(const char *Cmd) {
CLIParserContext *ctx;
@ -196,14 +233,19 @@ static int CmdGallagherClone(const char *Cmd) {
"clone a GALLAGHER tag to a T55x7, Q5/T5555 or EM4305/4469 tag.",
"lf gallagher clone --raw 0FFD5461A9DA1346B2D1AC32\n"
"lf gallagher clone --q5 --raw 0FFD5461A9DA1346B2D1AC32 -> encode for Q5/T5555 tag\n"
"lf gallagher clone --em --raw 0FFD5461A9DA1346B2D1AC32 -> encode for EM4305/4469"
"lf gallagher clone --em --raw 0FFD5461A9DA1346B2D1AC32 -> encode for EM4305/4469\n"
"lf gallagher clone --rc 0 --fc 9876 --cn 1234 --il 1"
);
void *argtable[] = {
arg_param_begin,
arg_str1("r", "raw", "<hex>", "raw hex data. 12 bytes max"),
arg_str0("r", "raw", "<hex>", "raw hex data. 12 bytes max"),
arg_lit0(NULL, "q5", "optional - specify writing to Q5/T5555 tag"),
arg_lit0(NULL, "em", "optional - specify writing to EM4305/4469 tag"),
arg_int0(NULL, "rc", "<decimal>", "Region code. 4 bits max"),
arg_int0(NULL, "fc", "<decimal>", "Facility code. 2 bytes max"),
arg_int0(NULL, "cn", "<decimal>", "Card number. 3 bytes max"),
arg_int0(NULL, "il", "<decimal>", "Issue level. 4 bits max"),
arg_param_end
};
CLIExecWithReturn(ctx, Cmd, argtable, false);
@ -211,19 +253,68 @@ static int CmdGallagherClone(const char *Cmd) {
int raw_len = 0;
// skip first block, 3*4 = 12 bytes left
uint8_t raw[12] = {0};
CLIGetHexWithReturn(ctx, 1, raw, &raw_len);
CLIParamHexToBuf(arg_get_str(ctx, 1), raw, sizeof raw, &raw_len);
bool q5 = arg_get_lit(ctx, 2);
bool em = arg_get_lit(ctx, 3);
int16_t region_code = arg_get_int_def(ctx, 4, -1);
int32_t facility_code = arg_get_int_def(ctx, 5, -1);
uint64_t card_number = arg_get_int_def(ctx, 6, -1);
uint32_t issue_level = arg_get_int_def(ctx, 7, -1);
CLIParserFree(ctx);
bool use_raw = raw_len > 0;
if (q5 && em) {
PrintAndLogEx(FAILED, "Can't specify both Q5 and EM4305 at the same time");
return PM3_EINVARG;
}
if (region_code == -1 && facility_code == -1 && card_number == -1 && issue_level == -1) {
if (!use_raw) {
PrintAndLogEx(FAILED, "Must specify either raw data to clone, or rc/fc/cn/il");
return PM3_EINVARG;
}
}
else {
// --raw and --rc/fc/cn/il are mutually exclusive
if (use_raw) {
PrintAndLogEx(FAILED, "Can't specify both raw and rc/fc/cn/il at the same time");
return PM3_EINVARG;
}
// if one is set, all must be set
if (region_code == -1 || facility_code == -1 || card_number == -1 || issue_level == -1) {
PrintAndLogEx(FAILED, "If rc/fc/cn/il is specified, all must be set");
return PM3_EINVARG;
}
// validate input
if (region_code > 0x0f) {
PrintAndLogEx(FAILED, "Region code must be less than 16 (4 bits)");
return PM3_EINVARG;
}
if (facility_code > 0xffff) {
PrintAndLogEx(FAILED, "Facility code must be less than 65536 (2 bytes)");
return PM3_EINVARG;
}
if (card_number > 0xffffff) {
PrintAndLogEx(FAILED, "Card number must be less than 16777216 (3 bytes)");
return PM3_EINVARG;
}
if (issue_level > 0x0f) {
PrintAndLogEx(FAILED, "Issue level must be less than 16 (4 bits)");
return PM3_EINVARG;
}
}
uint32_t blocks[4];
for (uint8_t i = 1; i < ARRAYLEN(blocks); i++) {
blocks[i] = bytes_to_num(raw + ((i - 1) * 4), sizeof(uint32_t));
if (use_raw) {
for (uint8_t i = 1; i < ARRAYLEN(blocks); i++) {
blocks[i] = bytes_to_num(raw + ((i - 1) * 4), sizeof(uint32_t));
}
}
else {
// fill blocks 1 to 3 with Gallagher data
createBlocks(blocks + 1, region_code, facility_code, card_number, issue_level);
}
//Pac - compat mode, NRZ, data rate 40, 3 data blocks
@ -241,7 +332,8 @@ static int CmdGallagherClone(const char *Cmd) {
snprintf(cardtype, sizeof(cardtype), "EM4305/4469");
}
PrintAndLogEx(INFO, "Preparing to clone Gallagher to " _YELLOW_("%s") " with raw hex", cardtype);
PrintAndLogEx(INFO, "Preparing to clone Gallagher to " _YELLOW_("%s") " from %s.",
cardtype, use_raw ? "raw hex" : "specified data");
print_blocks(blocks, ARRAYLEN(blocks));
int res;