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better OTP update sanity check by @jmichelp. Checks every bytewise if any bit is 0

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iceman1001 2025-03-19 15:34:20 +01:00
commit 1bd811f7a1
1 changed files with 10 additions and 5 deletions
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15
armsrc/iso14443a.c
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@ -1742,12 +1742,17 @@ void SimulateIso14443aTag(uint8_t tagType, uint16_t flags, uint8_t *useruid, uin
}
// OTP sanity check
// Quite a bad one, one should look at all individual bits and see if anyone tries be set as zero
// we cheat and do fat 00000000 check instead
if (block == 0x03) {
if (memcmp(receivedCmd + 2, "\x00\x00\x00\x00", 4) == 0) {
// OTP can't be set back to zero
// send NACK 0x0 == invalid argument,
uint8_t orig[4] = {0};
emlGet(orig, 12 + MFU_DUMP_PREFIX_LENGTH, 4);
bool risky = false;
for (int i = 0; i < len; i++) {
risky |= orig[i] & ~receivedCmd[2 + i];
}
if (risky) {
EmSend4bit(CARD_NACK_IV);
goto jump;
}