github/proxmark3
1
0
Fork 0
mirror of https://github.com/Proxmark/proxmark3.git synced 2025-07-08 06:00:53 -07:00
Code Issues Projects Releases Packages Wiki Activity Actions

more verification on FDX-B tag demod - reduce...

Browse source 
... false positives
This commit is contained in:
marshmellow42 2015-07-05 23:35:00 -04:00
parent 7ce6e2c0b5
commit 29b6cacc6f
2 changed files with 8 additions and 6 deletions
Download patch file Download diff file Expand all files Collapse all files

4
client/cmddata.c
View file

@ -1491,9 +1491,9 @@ int CmdFDXBdemodBI(const char *Cmd){
setDemodBuf(BitStream, 128, preambleIndex); setDemodBuf(BitStream, 128, preambleIndex);
// remove but don't verify parity. (pType = 2) // remove marker bits (1's every 9th digit after preamble) (pType = 2)
size = removeParity(BitStream, preambleIndex + 11, 9, 2, 117); size = removeParity(BitStream, preambleIndex + 11, 9, 2, 117);
if ( size <= 103 ) { if ( size != 104 ) {
if (g_debugMode) PrintAndLog("Error removeParity:: %d", size); if (g_debugMode) PrintAndLog("Error removeParity:: %d", size);
return 0; return 0;
} }

10
common/lfdemod.c
View file

@ -580,7 +580,7 @@ int IOdemodFSK(uint8_t *dest, size_t size)
// by marshmellow // by marshmellow
// takes a array of binary values, start position, length of bits per parity (includes parity bit), // 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 just drop it), and binary Length (length to run) // Parity Type (1 for odd; 0 for even; 2 Always 1'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) size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t pType, size_t bLen)
{ {
uint32_t parityWd = 0; uint32_t parityWd = 0;
@ -590,10 +590,12 @@ size_t removeParity(uint8_t *BitStream, size_t startIdx, uint8_t pLen, uint8_t p
parityWd = (parityWd << 1) | BitStream[startIdx+word+bit]; parityWd = (parityWd << 1) | BitStream[startIdx+word+bit];
BitStream[j++] = (BitStream[startIdx+word+bit]); BitStream[j++] = (BitStream[startIdx+word+bit]);
} }
j--; j--; // overwrite parity with next data
// if parity fails then return 0 // if parity fails then return 0
if (pType != 2) { if (pType == 2) { // then marker bit which should be a 1
if (parityTest(parityWd, pLen, pType) == 0) return -1; if (!BitStream[j]) return 0;
} else {
if (parityTest(parityWd, pLen, pType) == 0) return 0;
} }
bitCnt+=(pLen-1); bitCnt+=(pLen-1);
parityWd = 0; parityWd = 0;