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(implementing suggestion #94)

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hf mf mifare: gracefully exit if tag isn't vulnerable to this attack
hf mf nested: dito
This commit is contained in:
pwpiwi 2015-06-24 07:48:36 +02:00
commit dc8ba239fb
4 changed files with 83 additions and 43 deletions
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27
armsrc/iso14443a.c
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@ -1971,7 +1971,7 @@ int32_t dist_nt(uint32_t nt1, uint32_t nt2) {
nttmp1 = prng_successor(nttmp1, 1);
if (nttmp1 == nt2) return i;
nttmp2 = prng_successor(nttmp2, 1);
if (nttmp2 == nt1) return -i;
if (nttmp2 == nt1) return -i;
}
return(-99999); // either nt1 or nt2 are invalid nonces
@ -2040,18 +2040,21 @@ void ReaderMifare(bool first_try)
LED_B_OFF();
LED_C_OFF();
#define DARKSIDE_MAX_TRIES 32 // number of tries to sync on PRNG cycle. Then give up.
uint16_t unsuccessfull_tries = 0;
for(uint16_t i = 0; TRUE; i++) {
LED_C_ON();
WDT_HIT();
// Test if the action was cancelled
if(BUTTON_PRESS()) {
isOK = -1;
break;
}
LED_C_ON();
if(!iso14443a_select_card(uid, NULL, &cuid)) {
if (MF_DBGLEVEL >= 1) Dbprintf("Mifare: Can't select card");
continue;
@ -2086,8 +2089,14 @@ void ReaderMifare(bool first_try)
nt_attacked = nt;
}
else {
if (nt_distance == -99999) { // invalid nonce received, try again
continue;
if (nt_distance == -99999) { // invalid nonce received
unsuccessfull_tries++;
if (!nt_attacked && unsuccessfull_tries > DARKSIDE_MAX_TRIES) {
isOK = -3; // Card has an unpredictable PRNG. Give up
break;
} else {
continue; // continue trying...
}
}
sync_cycles = (sync_cycles - nt_distance);
if (MF_DBGLEVEL >= 3) Dbprintf("calibrating in cycle %d. nt_distance=%d, Sync_cycles: %d\n", i, nt_distance, sync_cycles);
@ -2149,6 +2158,10 @@ void ReaderMifare(bool first_try)
if (nt_diff == 0 && first_try)
{
par[0]++;
if (par[0] == 0x00) { // tried all 256 possible parities without success. Card doesn't send NACK.
isOK = -2;
break;
}
} else {
par[0] = ((par[0] & 0x1F) + 1) | par_low;
}
@ -2165,7 +2178,7 @@ void ReaderMifare(bool first_try)
memcpy(buf + 16, ks_list, 8);
memcpy(buf + 24, mf_nr_ar, 4);
cmd_send(CMD_ACK,isOK,0,0,buf,28);
cmd_send(CMD_ACK, isOK, 0, 0, buf, 28);
// Thats it...
FpgaWriteConfWord(FPGA_MAJOR_MODE_OFF);