Merge pull request #259 from marshmellow42/master

fix/update removeParity & fix securakey detection

diff --git a/client/cmdlfsecurakey.c b/client/cmdlfsecurakey.c
index 1d55faf91a6a08b9b96b0f13e78a5106f907ff98..1e3899db0732f76cb788724a25f402a374fc1ef5 100644 (file)
--- a/client/cmdlfsecurakey.c
+++ b/client/cmdlfsecurakey.c
@@ -83,33 +83,37 @@ int CmdSecurakeyDemod(const char *Cmd) {
        // y = card #
        // standard wiegand parities.
        // unknown checksum 11 bits? at the end
-       uint8_t bits_no_spacer[86];
-       memcpy(bits_no_spacer, DemodBuffer + 10, 86);
+       uint8_t bits_no_spacer[85];
+       memcpy(bits_no_spacer, DemodBuffer + 11, 85);
 
        // remove marker bits (0's every 9th digit after preamble) (pType = 3 (always 0s))
-       size = removeParity(bits_no_spacer, 0, 9, 3, 86);
-       if ( size != 86-10 ) {
+       size = removeParity(bits_no_spacer, 0, 9, 3, 85);
+       if ( size != 85-9 ) {
                if (g_debugMode) PrintAndLog("DEBUG: Error removeParity: %d", size);
                return 0;
        }
 
-       uint8_t bitLen = (uint8_t)bytebits_to_byte(DemodBuffer+2, 6);
+       uint8_t bitLen = (uint8_t)bytebits_to_byte(bits_no_spacer+2, 6);
        uint32_t fc=0, lWiegand=0, rWiegand=0;
-       // get FC
+       if (bitLen > 40) { //securakey's max bitlen is 40 bits...
+               if (g_debugMode) PrintAndLog("DEBUG: Error bitLen too long: %u", bitLen);
+               return 0;
+       }
        // get left 1/2 wiegand & right 1/2 wiegand (for parity test and wiegand print)
-       lWiegand = bytebits_to_byte(DemodBuffer + 48 - bitLen, bitLen/2);
-       rWiegand = bytebits_to_byte(DemodBuffer + 48 - bitLen + bitLen/2, bitLen/2);
-       fc = bytebits_to_byte(DemodBuffer+49-bitLen, bitLen-2-16);
+       lWiegand = bytebits_to_byte(bits_no_spacer + 48 - bitLen, bitLen/2);
+       rWiegand = bytebits_to_byte(bits_no_spacer + 48 - bitLen + bitLen/2, bitLen/2);
+       // get FC
+       fc = bytebits_to_byte(bits_no_spacer+49-bitLen, bitLen-2-16);
 
        // test bitLen
        if (bitLen != 26 && bitLen != 32)
                PrintAndLog("***unknown securakey bitLen - share with forum***");
 
-       uint32_t cardid = bytebits_to_byte(DemodBuffer+8+23, 16);
-       // test parities
-       bool parity = evenparity32(lWiegand) && oddparity32(rWiegand);
+       uint32_t cardid = bytebits_to_byte(bits_no_spacer+8+23, 16);
+       // test parities - evenparity32 looks to add an even parity returns 0 if already even...
+       bool parity = !evenparity32(lWiegand) && !oddparity32(rWiegand);
 
-       PrintAndLog("Securakey Tag Found--BitLen: %u, Card ID: %u, FC: %X, Raw: %08X%08X%08X", bitLen, cardid, fc, raw1 ,raw2, raw3);
+       PrintAndLog("Securakey Tag Found--BitLen: %u, Card ID: %u, FC: 0x%X, Raw: %08X%08X%08X", bitLen, cardid, fc, raw1 ,raw2, raw3);
        if (bitLen <= 32)
                PrintAndLog("Wiegand: %08X, Parity: %s", (lWiegand<<(bitLen/2)) | rWiegand, parity ? "Passed" : "Failed");
        PrintAndLog("\nHow the FC translates to printed FC is unknown");

diff --git a/common/lfdemod.c b/common/lfdemod.c
index eb84203e040b0f83f3d6b162dcadc0562aa13f24..c56301c07f07ab75c0da0499fbf59d504e204859 100644 (file)
--- a/common/lfdemod.c
+++ b/common/lfdemod.c
@@ -35,6 +35,7 @@
 #include <string.h>  // for memset, memcmp and size_t
 #include <stdint.h>  // for uint_32+
 #include <stdbool.h> // for bool
+#include "parity.h"  // for parity test
 
 //**********************************************************************************************
 //---------------------------------Utilities Section--------------------------------------------
@@ -82,40 +83,35 @@ int getHiLo(uint8_t *BitStream, size_t size, int *high, int *low, uint8_t fuzzHi
 // by marshmellow
 // pass bits to be tested in bits, length bits passed in bitLen, and parity type (even=0 | odd=1) in pType
 // returns 1 if passed
-uint8_t parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType) {
-       uint8_t ans = 0;
-       for (uint8_t i = 0; i < bitLen; i++){
-               ans ^= ((bits >> i) & 1);
-       }
-       if (g_debugMode) prnt("DEBUG: ans: %d, ptype: %d, bits: %08X",ans,pType,bits);
-       return (ans == pType);
+bool parityTest(uint32_t bits, uint8_t bitLen, uint8_t pType) {
+       return oddparity32(bits) ^ pType;
 }
 
 // by marshmellow
-// takes a array of binary values, start position, length of bits per parity (includes parity bit),
-//   Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run) 
+// takes a array of binary values, start position, length of bits per parity (includes parity bit - MAX 32),
+//   Parity Type (1 for odd; 0 for even; 2 for Always 1's; 3 for Always 0's), and binary Length (length to run)
 size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen) {
        uint32_t parityWd = 0;
-       size_t j = 0, bitCnt = 0;
+       size_t bitCnt = 0;
        for (int word = 0; word < (bLen); word+=pLen) {
                for (int bit=0; bit < pLen; bit++) {
+                       if (word+bit >= bLen) break;
                        parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
-                       BitStream[j++] = (BitStream[startIdx+word+bit]);
+                       BitStream[bitCnt++] = (BitStream[startIdx+word+bit]);
                }
                if (word+pLen > bLen) break;
 
-               j--; // overwrite parity with next data
+               bitCnt--; // overwrite parity with next data
                // if parity fails then return 0
                switch (pType) {
-                       case 3: if (BitStream[j]==1) {return 0;} break; //should be 0 spacer bit
-                       case 2: if (BitStream[j]==0) {return 0;} break; //should be 1 spacer bit
+                       case 3: if (BitStream[bitCnt]==1) {return 0;} break; //should be 0 spacer bit
+                       case 2: if (BitStream[bitCnt]==0) {return 0;} break; //should be 1 spacer bit
                        default: if (parityTest(parityWd, pLen, pType) == 0) {return 0;} break; //test parity
                }
-               bitCnt+=(pLen-1);
                parityWd = 0;
        }
        // if we got here then all the parities passed
-       //return ID start index and size
+       //return size
        return bitCnt;
 }
 
@@ -1687,6 +1683,7 @@ uint8_t Em410xDecode(uint8_t *BitStream, size_t *size, size_t *startIdx, uint32_
                *hi = (bytebits_to_byte(BitStream, 24)); 
                *lo = ((uint64_t)(bytebits_to_byte(BitStream + 24, 32)) << 32) | (bytebits_to_byte(BitStream + 24 + 32, 32));
        } else {
+               if (g_debugMode) prnt("Error removing parity: %u", *size);
                return 0;
        }
        return 1;