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ADD: 'hf 14a read' - detection if found Mifare Classic tag has a weak or hardend PRNG. Thanks to @doegox for implementing it in nfc-tools/mfoc Its a beauty :)

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iceman1001 2017-06-26 21:45:22 +02:00
commit 4d18909596
5 changed files with 91 additions and 36 deletions
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31
client/mifarehost.c
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@ -675,3 +675,34 @@ int tryDecryptWord(uint32_t nt, uint32_t ar_enc, uint32_t at_enc, uint8_t *data,
crypto1_destroy(s);
return 0;
}
/* Detect Tag Prng,
* function performs a partial AUTH, where it tries to authenticate against block0, key A, but only collects tag nonce.
* the tag nonce is check to see if it has a predictable PRNG.
* @returns
* TRUE if tag uses WEAK prng (ie Darkside attack possible)
* FALSE is tag uses HARDEND prng (ie hardnested attack possible, with known key)
*/
bool detect_classic_prng(){
UsbCommand resp, respA;
uint8_t cmd[] = {MIFARE_AUTH_KEYA, 0x00};
uint32_t flags = ISO14A_CONNECT | ISO14A_RAW | ISO14A_APPEND_CRC;
UsbCommand cAuth = {CMD_READER_ISO_14443a, {flags, sizeof(cmd), 0}};
memcpy(cAuth.d.asBytes, cmd, sizeof(cmd));
clearCommandBuffer();
SendCommand(&cAuth);
WaitForResponse(CMD_ACK, &resp);
WaitForResponse(CMD_ACK, &respA);
// if select tag failed.
if ( resp.arg[0] == 0 ) {
printf("Error: selecting tag failed, can't detect prng\n");
return false;
}
uint32_t nonce = bytes_to_num(respA.d.asBytes, respA.arg[0]);
return validate_prng_nonce(nonce);
}