473 lines
15 KiB
C
473 lines
15 KiB
C
#include <furi.h>
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#include "u2f_data.h"
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#include <furi_hal.h>
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#include <storage/storage.h>
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#include <furi_hal_random.h>
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#include <flipper_format/flipper_format.h>
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#define TAG "U2F"
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#define U2F_DATA_FOLDER ANY_PATH("u2f/")
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#define U2F_CERT_FILE U2F_DATA_FOLDER "assets/cert.der"
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#define U2F_CERT_KEY_FILE U2F_DATA_FOLDER "assets/cert_key.u2f"
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#define U2F_KEY_FILE U2F_DATA_FOLDER "key.u2f"
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#define U2F_CNT_FILE U2F_DATA_FOLDER "cnt.u2f"
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#define U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_FACTORY 2
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#define U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE 11
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#define U2F_CERT_STOCK 0 // Stock certificate, private key is encrypted with factory key
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#define U2F_CERT_USER 1 // User certificate, private key is encrypted with unique key
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#define U2F_CERT_USER_UNENCRYPTED \
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2 // Unencrypted user certificate, will be encrypted after first load
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#define U2F_CERT_KEY_FILE_TYPE "Flipper U2F Certificate Key File"
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#define U2F_CERT_KEY_VERSION 1
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#define U2F_DEVICE_KEY_FILE_TYPE "Flipper U2F Device Key File"
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#define U2F_DEVICE_KEY_VERSION 1
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#define U2F_COUNTER_FILE_TYPE "Flipper U2F Counter File"
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#define U2F_COUNTER_VERSION 2
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#define U2F_COUNTER_VERSION_OLD 1
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#define U2F_COUNTER_CONTROL_VAL 0xAA5500FF
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typedef struct {
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uint32_t counter;
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uint8_t random_salt[24];
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uint32_t control;
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} __attribute__((packed)) U2fCounterData;
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bool u2f_data_check(bool cert_only) {
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bool state = false;
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Storage* fs_api = furi_record_open(RECORD_STORAGE);
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File* file = storage_file_alloc(fs_api);
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do {
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if(!storage_file_open(file, U2F_CERT_FILE, FSAM_READ, FSOM_OPEN_EXISTING)) break;
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storage_file_close(file);
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if(!storage_file_open(file, U2F_CERT_KEY_FILE, FSAM_READ, FSOM_OPEN_EXISTING)) break;
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if(cert_only) {
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state = true;
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break;
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}
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storage_file_close(file);
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if(!storage_file_open(file, U2F_KEY_FILE, FSAM_READ, FSOM_OPEN_EXISTING)) break;
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storage_file_close(file);
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if(!storage_file_open(file, U2F_CNT_FILE, FSAM_READ, FSOM_OPEN_EXISTING)) break;
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state = true;
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} while(0);
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storage_file_close(file);
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storage_file_free(file);
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furi_record_close(RECORD_STORAGE);
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return state;
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}
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bool u2f_data_cert_check() {
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bool state = false;
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Storage* fs_api = furi_record_open(RECORD_STORAGE);
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File* file = storage_file_alloc(fs_api);
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uint8_t file_buf[8];
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if(storage_file_open(file, U2F_CERT_FILE, FSAM_READ, FSOM_OPEN_EXISTING)) {
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do {
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// Read header to check certificate size
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size_t file_size = storage_file_size(file);
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size_t len_cur = storage_file_read(file, file_buf, 4);
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if(len_cur != 4) break;
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if(file_buf[0] != 0x30) {
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FURI_LOG_E(TAG, "Wrong certificate header");
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break;
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}
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size_t temp_len = ((file_buf[2] << 8) | (file_buf[3])) + 4;
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if(temp_len != file_size) {
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FURI_LOG_E(TAG, "Wrong certificate length");
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break;
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}
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state = true;
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} while(0);
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}
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storage_file_close(file);
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storage_file_free(file);
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furi_record_close(RECORD_STORAGE);
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return state;
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}
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uint32_t u2f_data_cert_load(uint8_t* cert) {
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furi_assert(cert);
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Storage* fs_api = furi_record_open(RECORD_STORAGE);
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File* file = storage_file_alloc(fs_api);
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uint32_t file_size = 0;
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uint32_t len_cur = 0;
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if(storage_file_open(file, U2F_CERT_FILE, FSAM_READ, FSOM_OPEN_EXISTING)) {
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file_size = storage_file_size(file);
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len_cur = storage_file_read(file, cert, file_size);
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if(len_cur != file_size) len_cur = 0;
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}
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storage_file_close(file);
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storage_file_free(file);
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furi_record_close(RECORD_STORAGE);
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return len_cur;
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}
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static bool u2f_data_cert_key_encrypt(uint8_t* cert_key) {
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furi_assert(cert_key);
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bool state = false;
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uint8_t iv[16];
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uint8_t key[48];
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uint32_t cert_type = U2F_CERT_USER;
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FURI_LOG_I(TAG, "Encrypting user cert key");
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// Generate random IV
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furi_hal_random_fill_buf(iv, 16);
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if(!furi_hal_crypto_store_load_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE, iv)) {
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FURI_LOG_E(TAG, "Unable to load encryption key");
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return false;
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}
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if(!furi_hal_crypto_encrypt(cert_key, key, 32)) {
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FURI_LOG_E(TAG, "Encryption failed");
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return false;
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}
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furi_hal_crypto_store_unload_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE);
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Storage* storage = furi_record_open(RECORD_STORAGE);
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FlipperFormat* flipper_format = flipper_format_file_alloc(storage);
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if(flipper_format_file_open_always(flipper_format, U2F_CERT_KEY_FILE)) {
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do {
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if(!flipper_format_write_header_cstr(
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flipper_format, U2F_CERT_KEY_FILE_TYPE, U2F_CERT_KEY_VERSION))
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break;
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if(!flipper_format_write_uint32(flipper_format, "Type", &cert_type, 1)) break;
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if(!flipper_format_write_hex(flipper_format, "IV", iv, 16)) break;
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if(!flipper_format_write_hex(flipper_format, "Data", key, 48)) break;
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state = true;
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} while(0);
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}
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flipper_format_free(flipper_format);
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furi_record_close(RECORD_STORAGE);
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return state;
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}
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bool u2f_data_cert_key_load(uint8_t* cert_key) {
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furi_assert(cert_key);
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bool state = false;
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uint8_t iv[16];
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uint8_t key[48];
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uint32_t cert_type = 0;
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uint8_t key_slot = 0;
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uint32_t version = 0;
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// Check if unique key exists in secure eclave and generate it if missing
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if(!furi_hal_crypto_verify_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE)) return false;
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string_t filetype;
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string_init(filetype);
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Storage* storage = furi_record_open(RECORD_STORAGE);
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FlipperFormat* flipper_format = flipper_format_file_alloc(storage);
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if(flipper_format_file_open_existing(flipper_format, U2F_CERT_KEY_FILE)) {
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do {
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if(!flipper_format_read_header(flipper_format, filetype, &version)) {
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FURI_LOG_E(TAG, "Missing or incorrect header");
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break;
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}
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if(strcmp(string_get_cstr(filetype), U2F_CERT_KEY_FILE_TYPE) != 0 ||
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version != U2F_CERT_KEY_VERSION) {
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FURI_LOG_E(TAG, "Type or version mismatch");
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break;
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}
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if(!flipper_format_read_uint32(flipper_format, "Type", &cert_type, 1)) {
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FURI_LOG_E(TAG, "Missing cert type");
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break;
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}
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if(cert_type == U2F_CERT_STOCK) {
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key_slot = U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_FACTORY;
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} else if(cert_type == U2F_CERT_USER) {
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key_slot = U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE;
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} else if(cert_type == U2F_CERT_USER_UNENCRYPTED) {
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key_slot = 0;
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} else {
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FURI_LOG_E(TAG, "Unknown cert type");
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break;
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}
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if(key_slot != 0) {
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if(!flipper_format_read_hex(flipper_format, "IV", iv, 16)) {
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FURI_LOG_E(TAG, "Missing IV");
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break;
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}
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if(!flipper_format_read_hex(flipper_format, "Data", key, 48)) {
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FURI_LOG_E(TAG, "Missing data");
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break;
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}
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if(!furi_hal_crypto_store_load_key(key_slot, iv)) {
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FURI_LOG_E(TAG, "Unable to load encryption key");
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break;
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}
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memset(cert_key, 0, 32);
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if(!furi_hal_crypto_decrypt(key, cert_key, 32)) {
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memset(cert_key, 0, 32);
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FURI_LOG_E(TAG, "Decryption failed");
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break;
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}
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furi_hal_crypto_store_unload_key(key_slot);
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} else {
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if(!flipper_format_read_hex(flipper_format, "Data", cert_key, 32)) {
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FURI_LOG_E(TAG, "Missing data");
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break;
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}
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}
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state = true;
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} while(0);
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}
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flipper_format_free(flipper_format);
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furi_record_close(RECORD_STORAGE);
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string_clear(filetype);
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if(cert_type == U2F_CERT_USER_UNENCRYPTED) {
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return u2f_data_cert_key_encrypt(cert_key);
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}
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return state;
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}
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bool u2f_data_key_load(uint8_t* device_key) {
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furi_assert(device_key);
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bool state = false;
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uint8_t iv[16];
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uint8_t key[48];
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uint32_t version = 0;
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string_t filetype;
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string_init(filetype);
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Storage* storage = furi_record_open(RECORD_STORAGE);
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FlipperFormat* flipper_format = flipper_format_file_alloc(storage);
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if(flipper_format_file_open_existing(flipper_format, U2F_KEY_FILE)) {
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do {
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if(!flipper_format_read_header(flipper_format, filetype, &version)) {
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FURI_LOG_E(TAG, "Missing or incorrect header");
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break;
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}
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if(strcmp(string_get_cstr(filetype), U2F_DEVICE_KEY_FILE_TYPE) != 0 ||
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version != U2F_DEVICE_KEY_VERSION) {
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FURI_LOG_E(TAG, "Type or version mismatch");
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break;
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}
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if(!flipper_format_read_hex(flipper_format, "IV", iv, 16)) {
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FURI_LOG_E(TAG, "Missing IV");
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break;
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}
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if(!flipper_format_read_hex(flipper_format, "Data", key, 48)) {
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FURI_LOG_E(TAG, "Missing data");
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break;
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}
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if(!furi_hal_crypto_store_load_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE, iv)) {
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FURI_LOG_E(TAG, "Unable to load encryption key");
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break;
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}
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memset(device_key, 0, 32);
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if(!furi_hal_crypto_decrypt(key, device_key, 32)) {
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memset(device_key, 0, 32);
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FURI_LOG_E(TAG, "Decryption failed");
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break;
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}
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furi_hal_crypto_store_unload_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE);
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state = true;
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} while(0);
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}
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flipper_format_free(flipper_format);
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furi_record_close(RECORD_STORAGE);
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string_clear(filetype);
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return state;
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}
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bool u2f_data_key_generate(uint8_t* device_key) {
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furi_assert(device_key);
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bool state = false;
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uint8_t iv[16];
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uint8_t key[32];
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uint8_t key_encrypted[48];
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// Generate random IV and key
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furi_hal_random_fill_buf(iv, 16);
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furi_hal_random_fill_buf(key, 32);
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if(!furi_hal_crypto_store_load_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE, iv)) {
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FURI_LOG_E(TAG, "Unable to load encryption key");
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return false;
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}
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if(!furi_hal_crypto_encrypt(key, key_encrypted, 32)) {
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FURI_LOG_E(TAG, "Encryption failed");
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return false;
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}
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furi_hal_crypto_store_unload_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE);
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Storage* storage = furi_record_open(RECORD_STORAGE);
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FlipperFormat* flipper_format = flipper_format_file_alloc(storage);
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if(flipper_format_file_open_always(flipper_format, U2F_KEY_FILE)) {
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do {
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if(!flipper_format_write_header_cstr(
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flipper_format, U2F_DEVICE_KEY_FILE_TYPE, U2F_DEVICE_KEY_VERSION))
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break;
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if(!flipper_format_write_hex(flipper_format, "IV", iv, 16)) break;
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if(!flipper_format_write_hex(flipper_format, "Data", key_encrypted, 48)) break;
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state = true;
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memcpy(device_key, key, 32);
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} while(0);
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}
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flipper_format_free(flipper_format);
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furi_record_close(RECORD_STORAGE);
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return state;
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}
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bool u2f_data_cnt_read(uint32_t* cnt_val) {
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furi_assert(cnt_val);
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bool state = false;
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bool old_counter = false;
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uint8_t iv[16];
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U2fCounterData cnt;
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uint8_t cnt_encr[48];
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uint32_t version = 0;
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string_t filetype;
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string_init(filetype);
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Storage* storage = furi_record_open(RECORD_STORAGE);
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FlipperFormat* flipper_format = flipper_format_file_alloc(storage);
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if(flipper_format_file_open_existing(flipper_format, U2F_CNT_FILE)) {
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do {
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if(!flipper_format_read_header(flipper_format, filetype, &version)) {
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FURI_LOG_E(TAG, "Missing or incorrect header");
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break;
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}
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if(strcmp(string_get_cstr(filetype), U2F_COUNTER_FILE_TYPE) != 0) {
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FURI_LOG_E(TAG, "Type mismatch");
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break;
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}
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if(version == U2F_COUNTER_VERSION_OLD) {
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// Counter is from previous U2F app version with endianness bug
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FURI_LOG_W(TAG, "Counter from old version");
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old_counter = true;
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} else if(version != U2F_COUNTER_VERSION) {
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FURI_LOG_E(TAG, "Version mismatch");
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break;
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}
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if(!flipper_format_read_hex(flipper_format, "IV", iv, 16)) {
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FURI_LOG_E(TAG, "Missing IV");
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break;
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}
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if(!flipper_format_read_hex(flipper_format, "Data", cnt_encr, 48)) {
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FURI_LOG_E(TAG, "Missing data");
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break;
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}
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if(!furi_hal_crypto_store_load_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE, iv)) {
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FURI_LOG_E(TAG, "Unable to load encryption key");
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break;
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}
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memset(&cnt, 0, 32);
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if(!furi_hal_crypto_decrypt(cnt_encr, (uint8_t*)&cnt, 32)) {
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memset(&cnt, 0, 32);
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FURI_LOG_E(TAG, "Decryption failed");
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break;
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}
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furi_hal_crypto_store_unload_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE);
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if(cnt.control == U2F_COUNTER_CONTROL_VAL) {
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*cnt_val = cnt.counter;
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state = true;
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}
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} while(0);
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}
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flipper_format_free(flipper_format);
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furi_record_close(RECORD_STORAGE);
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string_clear(filetype);
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if(old_counter && state) {
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// Change counter endianness and rewrite counter file
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*cnt_val = __REV(cnt.counter);
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state = u2f_data_cnt_write(*cnt_val);
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}
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return state;
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}
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bool u2f_data_cnt_write(uint32_t cnt_val) {
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bool state = false;
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uint8_t iv[16];
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U2fCounterData cnt;
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uint8_t cnt_encr[48];
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// Generate random IV and key
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furi_hal_random_fill_buf(iv, 16);
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furi_hal_random_fill_buf(cnt.random_salt, 24);
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cnt.control = U2F_COUNTER_CONTROL_VAL;
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cnt.counter = cnt_val;
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if(!furi_hal_crypto_store_load_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE, iv)) {
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FURI_LOG_E(TAG, "Unable to load encryption key");
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return false;
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}
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if(!furi_hal_crypto_encrypt((uint8_t*)&cnt, cnt_encr, 32)) {
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FURI_LOG_E(TAG, "Encryption failed");
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return false;
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}
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furi_hal_crypto_store_unload_key(U2F_DATA_FILE_ENCRYPTION_KEY_SLOT_UNIQUE);
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Storage* storage = furi_record_open(RECORD_STORAGE);
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FlipperFormat* flipper_format = flipper_format_file_alloc(storage);
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if(flipper_format_file_open_always(flipper_format, U2F_CNT_FILE)) {
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do {
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if(!flipper_format_write_header_cstr(
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|
flipper_format, U2F_COUNTER_FILE_TYPE, U2F_COUNTER_VERSION))
|
|
break;
|
|
if(!flipper_format_write_hex(flipper_format, "IV", iv, 16)) break;
|
|
if(!flipper_format_write_hex(flipper_format, "Data", cnt_encr, 48)) break;
|
|
state = true;
|
|
} while(0);
|
|
}
|
|
|
|
flipper_format_free(flipper_format);
|
|
furi_record_close(RECORD_STORAGE);
|
|
|
|
return state;
|
|
}
|