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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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22
armsrc/mifarecmd.c
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@ -645,6 +645,9 @@ void MifareNested(uint32_t arg0, uint32_t arg1, uint32_t calibrate, uint8_t *dat
// statistics on nonce distance
int16_t isOK = 0;
#define NESTED_MAX_TRIES 12
uint16_t unsuccessfull_tries = 0;
if (calibrate) { // for first call only. Otherwise reuse previous calibration
LED_B_ON();
WDT_HIT();
@ -655,6 +658,12 @@ void MifareNested(uint32_t arg0, uint32_t arg1, uint32_t calibrate, uint8_t *dat
for (rtr = 0; rtr < 17; rtr++) {
// Test if the action was cancelled
if(BUTTON_PRESS()) {
isOK = -2;
break;
}
// prepare next select. No need to power down the card.
if(mifare_classic_halt(pcs, cuid)) {
if (MF_DBGLEVEL >= 1) Dbprintf("Nested: Halt error");
@ -702,14 +711,17 @@ void MifareNested(uint32_t arg0, uint32_t arg1, uint32_t calibrate, uint8_t *dat
delta_time = auth2_time - auth1_time + 32; // allow some slack for proper timing
}
if (MF_DBGLEVEL >= 3) Dbprintf("Nested: calibrating... ntdist=%d", i);
} else {
unsuccessfull_tries++;
if (unsuccessfull_tries > NESTED_MAX_TRIES) { // card isn't vulnerable to nested attack (random numbers are not predictable)
isOK = -3;
}
}
}
if (rtr <= 1) return;
davg = (davg + (rtr - 1)/2) / (rtr - 1);
if (MF_DBGLEVEL >= 3) Dbprintf("min=%d max=%d avg=%d, delta_time=%d", dmin, dmax, davg, delta_time);
if (MF_DBGLEVEL >= 3) Dbprintf("rtr=%d isOK=%d min=%d max=%d avg=%d, delta_time=%d", rtr, isOK, dmin, dmax, davg, delta_time);
dmin = davg - 2;
dmax = davg + 2;
@ -722,7 +734,7 @@ void MifareNested(uint32_t arg0, uint32_t arg1, uint32_t calibrate, uint8_t *dat
LED_C_ON();
// get crypted nonces for target sector
for(i=0; i < 2; i++) { // look for exactly two different nonces
for(i=0; i < 2 && !isOK; i++) { // look for exactly two different nonces
target_nt[i] = 0;
while(target_nt[i] == 0) { // continue until we have an unambiguous nonce
@ -800,7 +812,7 @@ void MifareNested(uint32_t arg0, uint32_t arg1, uint32_t calibrate, uint8_t *dat
memcpy(buf+16, &target_ks[1], 4);
LED_B_ON();
cmd_send(CMD_ACK, 0, 2, targetBlockNo + (targetKeyType * 0x100), buf, sizeof(buf));
cmd_send(CMD_ACK, isOK, 0, targetBlockNo + (targetKeyType * 0x100), buf, sizeof(buf));
LED_B_OFF();
if (MF_DBGLEVEL >= 3) DbpString("NESTED FINISHED");