From f655391bd4fb83cd1cd5f5e30cb5ecbb9679ae39 Mon Sep 17 00:00:00 2001 From: DarkMatterMatt Date: Thu, 11 Feb 2021 00:17:48 +1300 Subject: [PATCH] Initial implementation of encoding --- client/src/cmdlfgallagher.c | 108 +++++++++++++++++++++++++++++++++--- 1 file changed, 100 insertions(+), 8 deletions(-) diff --git a/client/src/cmdlfgallagher.c b/client/src/cmdlfgallagher.c index c83e5282e..7d9c3387f 100644 --- a/client/src/cmdlfgallagher.c +++ b/client/src/cmdlfgallagher.c @@ -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", "", "raw hex data. 12 bytes max"), + arg_str0("r", "raw", "", "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", "", "Region code. 4 bits max"), + arg_int0(NULL, "fc", "", "Facility code. 2 bytes max"), + arg_int0(NULL, "cn", "", "Card number. 3 bytes max"), + arg_int0(NULL, "il", "", "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;