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unleashed-firmware/applications/u2f/u2f_data.c
Nikolay Minaylov 6c268ec581
U2F: counter file migration (#1604) 
Co-authored-by: あく <alleteam@gmail.com>
2022-08-18 00:40:06 +09:00

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