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I have attached a patch to command.c that retrieves the read legic rf data and displays it in a deobfuscated manner.
Code is quite ugly, please feel free to improve... (license: GPL v2).
---
Index: client/command.c
===================================================================
--- client/command.c (Revision 303)
+++ client/command.c (Arbeitskopie)
@@ -2792,6 +2792,177 @@
SendCommand(&c);
}
+/*
+ * Output BigBuf and deobfuscate LEGIC RF tag data.
+ * This is based on information given in the talk held
+ * by Henryk Ploetz and Karsten Nohl at 26c3
+ * FIXME: will crash if sample buffer does not contain valid legic data
+ */
+static void CmdLegicDecode()
+{
+ int h, i, j, k, n;
+ int segment_len = 0;
+ int segment_flag = 0;
+ int stamp_len = 0;
+ int crc = 0;
+ int wrp = 0;
+ int wrc = 0;
+ int data_buf[1032]; // receiver buffer
+ char out_string[3076]; // just use big buffer - bad practice
+ char token_type[4];
+ int delivered = 0;
+
+ h = 0;
+
+ // copy data from proxmark into buffer
+ for (i = 0; i < 256; i += 12, h += 48) {
+ UsbCommand c = {CMD_DOWNLOAD_RAW_ADC_SAMPLES_125K, {i, 0, 0}};
+ SendCommand(&c);
+ wait_for_response(CMD_DOWNLOADED_RAW_ADC_SAMPLES_125K);
+
+ for (j = 0; j < 48; j += 8) {
+ for (k = 0; k < 8; k++) {
+ data_buf[h+j+k] = sample_buf[j+k];
+ }
+ delivered += 8;
+ if (delivered >= 1024)
+ break;
+ }
+ }
+
+ // Output CDF System area (9 bytes) plus remaining header area (12 bytes)
+
+ PrintToScrollback("\nCDF: System Area");
+
+ PrintToScrollback("MCD: %02x, MSN: %02x %02x %02x, MCC: %02x",
+ data_buf[0],
+ data_buf[1],
+ data_buf[2],
+ data_buf[3],
+ data_buf[4]
+ );
+
+ crc = data_buf[4];
+
+ switch (data_buf[5]&0x7f) {
+ case 0x00 ... 0x2f:
+ strcpy(token_type, "IAM");
+ break;
+ case 0x30 ... 0x6f:
+ strcpy(token_type, "SAM");
+ break;
+ case 0x70 ... 0x7f:
+ strcpy(token_type, "GAM");
+ break;
+ default:
+ strcpy(token_type, "???");
+ break;
+ }
+
+ stamp_len = 0xfc - data_buf[6];
+
+ PrintToScrollback("DCF: %02x %02x, Token_Type=%s (OLE=%01u), Stamp_len=%02u",
+ data_buf[5],
+ data_buf[6],
+ token_type,
+ (data_buf[5]&0x80)>>7,
+ stamp_len
+ );
+
+ PrintToScrollback("WRP=%02u, WRC=%01u, RD=%01u, raw=%02x, SSC=%02x",
+ data_buf[7]&0x0f,
+ (data_buf[7]&0x70)>>4,
+ (data_buf[7]&0x80)>>7,
+ data_buf[7],
+ data_buf[8]
+ );
+
+ PrintToScrollback("Remaining Header Area");
+
+ PrintToScrollback("%02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x %02x",
+ data_buf[9],
+ data_buf[10],
+ data_buf[11],
+ data_buf[12],
+ data_buf[13],
+ data_buf[14],
+ data_buf[15],
+ data_buf[16],
+ data_buf[17],
+ data_buf[18],
+ data_buf[19],
+ data_buf[20],
+ data_buf[21]
+ );
+
+ PrintToScrollback("\nADF: User Area");
+
+ i = 22;
+ for (n=0; n<64; n++) {
+ segment_len = ((data_buf[i+1]^crc)&0x0f) * 256 + (data_buf[i]^crc);
+ segment_flag = ((data_buf[i+1]^crc)&0xf0)>>4;
+
+ wrp = (data_buf[i+2]^crc);
+ wrc = ((data_buf[i+3]^crc)&0x70)>>4;
+
+ PrintToScrollback("Segment %02u: raw header=%02x %02x %02x %02x, flag=%01x (valid=%01u, last=%01u), len=%04u, WRP=%02u, WRC=%02u, RD=%01u, CRC=%02x",
+ n,
+ data_buf[i]^crc,
+ data_buf[i+1]^crc,
+ data_buf[i+2]^crc,
+ data_buf[i+3]^crc,
+ segment_flag,
+ (segment_flag&0x4)>>2,
+ (segment_flag&0x8)>>3,
+ segment_len,
+ wrp,
+ wrc,
+ ((data_buf[i+3]^crc)&0x80)>>7,
+ (data_buf[i+4]^crc)
+ );
+
+ i+=5;
+
+ // Output WRC protected area
+ if (wrc>0) {
+ for (k=0, j=0; k < wrc; k++, i++, j += 3) {
+ sprintf(&out_string[j], "%02x", (data_buf[i]^crc));
+ out_string[j+2] = ' ';
+ };
+
+ out_string[j] = '\0';
+
+ PrintToScrollback("%s", out_string);
+ }
+
+ // Output remaining write protected area
+ if (wrp>wrc) {
+ for (k=0, j=0; k < (wrp-wrc); k++, i++, j += 3) {
+ sprintf(&out_string[j], "%02x", (data_buf[i]^crc));
+ out_string[j+2] = ' ';
+ };
+
+ out_string[j] = '\0';
+
+ PrintToScrollback("%s", out_string);
+ }
+
+ // Output remaining segment payload
+ for (k=0, j=0; k < (segment_len - wrp - 5); k++, i++, j += 3) {
+ sprintf(&out_string[j], "%02x", (data_buf[i]^crc));
+ out_string[j+2] = ' ';
+ };
+
+ out_string[j] = '\0';
+
+ PrintToScrollback("%s", out_string);
+
+ // end with last segment
+ if (segment_flag & 0x8)
+ return;
+ };
+}
+
typedef void HandlerFunction(char *cmdline);
/* in alphabetic order */
@@ -2848,6 +3019,7 @@
{"lcd", CmdLcd, 0, "<HEX command> <count> -- Send command/data to LCD"},
{"lcdreset", CmdLcdReset, 0, "Hardware reset LCD"},
{"legicrfread", CmdLegicRfRead, 0, "Start the LEGIC RF reader"},
+ {"legicdecode", CmdLegicDecode, 0, "Display deobfuscated and decoded LEGIC RF tag data (use after legicrfread)"},
{"load", CmdLoad, 1, "<filename> -- Load trace (to graph window"},
{"locomread", CmdLoCommandRead, 0, "<off period> <'0' period> <'1' period> <command> ['h'] -- Modulate LF reader field to send command before read (all periods in microseconds) (option 'h' for 134)"},
{"loread", CmdLoread, 0, "['h'] -- Read 125/134 kHz LF ID-only tag (option 'h' for 134)"},Offline
Cool thanks
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