clone/pico-fido
1
0
Fork 0
mirror of https://github.com/polhenarejos/pico-fido synced 2026-04-27 09:07:41 +02:00
Code Issues Packages Projects Releases Wiki Activity

Remove unused MKEK system.

Browse Source 
Since previous releases, DKEK is double-encrypted with AAD, with OTP and PIN derivation, making not necessary an additional MKEK.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2026-03-12 23:41:22 +01:00
parent 4e7c40b2bd
commit f658ef6eab
7 changed files with 0 additions and 142 deletions
Download Patch File Download Diff File Expand all files Collapse all files

1
CMakeLists.txt
View File

@@ -97,7 +97,6 @@ endif()
list(APPEND SOURCES
${CMAKE_CURRENT_LIST_DIR}/src/fido/fido.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/files.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/kek.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/cmd_register.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/cmd_authenticate.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/cmd_version.c

1
src/fido/cbor_client_pin.c
View File

@@ -37,7 +37,6 @@
#include "random.h"
#include "crypto_utils.h"
#include "apdu.h"
#include "kek.h"
uint32_t usage_timer = 0, initial_usage_time_limit = 0;
uint32_t max_usage_time_period = 600 * 1000;

5
src/fido/fido.c
View File

@@ -17,7 +17,6 @@
#include "pico_keys.h"
#include "fido.h"
#include "kek.h"
#include "apdu.h"
#include "ctap.h"
#include "files.h"
@@ -226,9 +225,6 @@ int load_keydev(uint8_t key[32]) {
uint16_t fid_size = file_get_size(ef_keydev);
if (fid_size == 32) {
memcpy(key, file_get_data(ef_keydev), 32);
if (mkek_decrypt(key, 32) != PICOKEY_OK) {
return PICOKEY_EXEC_ERROR;
}
if (otp_key_1 && aes_decrypt(otp_key_1, NULL, 32 * 8, PICO_KEYS_AES_MODE_CBC, key, 32) != PICOKEY_OK) {
return PICOKEY_EXEC_ERROR;
}
@@ -372,7 +368,6 @@ int encrypt_keydev_f1(const uint8_t keydev[32]) {
int scan_files_fido(void) {
ef_keydev = search_by_fid(EF_KEY_DEV, NULL, SPECIFY_EF);
ef_keydev_enc = search_by_fid(EF_KEY_DEV_ENC, NULL, SPECIFY_EF);
ef_mkek = search_by_fid(EF_MKEK, NULL, SPECIFY_EF);
if (ef_keydev) {
if (!file_has_data(ef_keydev) && !file_has_data(ef_keydev_enc)) {
printf("KEY DEVICE is empty. Generating SECP256R1 curve...");

2
src/fido/files.c
View File

@@ -21,7 +21,6 @@ file_t file_entries[] = {
{ .fid = 0x3f00, .parent = 0xff, .name = NULL, .type = FILE_TYPE_DF, .data = NULL, .ef_structure = 0, .acl = { 0 } }, // MF
{ .fid = EF_KEY_DEV, .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = { 0xff } }, // Device Key
{ .fid = EF_KEY_DEV_ENC, .parent = 0, .name = NULL,.type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = { 0xff } }, // Device Key Enc
{ .fid = EF_MKEK, .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = { 0xff } }, // MKEK
{ .fid = EF_EE_DEV, .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = { 0xff } }, // End Entity Certificate Device
{ .fid = EF_EE_DEV_EA, .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = { 0xff } }, // End Entity Enterprise Attestation Certificate
{ .fid = EF_COUNTER, .parent = 0, .name = NULL, .type = FILE_TYPE_INTERNAL_EF | FILE_DATA_FLASH, .data = NULL, .ef_structure = FILE_EF_TRANSPARENT, .acl = { 0xff } }, // Global counter
@@ -46,4 +45,3 @@ file_t *ef_pin_admin = NULL;
file_t *ef_authtoken = NULL;
file_t *ef_keydev_enc = NULL;
file_t *ef_largeblob = NULL;
file_t *ef_mkek = NULL;

2
src/fido/files.h
View File

@@ -22,7 +22,6 @@
#define EF_KEY_DEV 0xCC00
#define EF_KEY_DEV_ENC 0xCC01
#define EF_MKEK 0xCC0F
#define EF_EE_DEV 0xCE00
#define EF_EE_DEV_EA 0xCE01
#define EF_COUNTER 0xC000
@@ -53,6 +52,5 @@ extern file_t *ef_pin_admin;
extern file_t *ef_authtoken;
extern file_t *ef_keydev_enc;
extern file_t *ef_largeblob;
extern file_t *ef_mkek;
#endif //_FILES_H_

85
src/fido/kek.c
View File

@@ -1,85 +0,0 @@
/*
* This file is part of the Pico Fido distribution (https://github.com/polhenarejos/pico-fido).
* Copyright (c) 2022 Pol Henarejos.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, version 3.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#include "pico_keys.h"
#include "fido.h"
#include "stdlib.h"
#if defined(PICO_PLATFORM)
#include "pico/stdlib.h"
#endif
#include "kek.h"
#include "crypto_utils.h"
#include "random.h"
#include "mbedtls/md.h"
#include "mbedtls/cmac.h"
#include "mbedtls/rsa.h"
#include "mbedtls/ecdsa.h"
#include "mbedtls/chachapoly.h"
#include "files.h"
#include "otp.h"
uint8_t mkek_mask[MKEK_KEY_SIZE];
bool has_mkek_mask = false;
static void mkek_masked(uint8_t *mkek, const uint8_t *mask) {
if (mask) {
for (int i = 0; i < MKEK_KEY_SIZE; i++) {
MKEK_KEY(mkek)[i] ^= mask[i];
}
}
}
int load_mkek(uint8_t *mkek) {
file_t *tf = search_file(EF_MKEK);
if (file_has_data(tf)) {
memcpy(mkek, file_get_data(tf), MKEK_SIZE);
}
if (has_mkek_mask) {
mkek_masked(mkek, mkek_mask);
}
if (file_get_size(tf) == MKEK_SIZE) {
int ret = aes_decrypt_cfb_256(session_pin, MKEK_IV(mkek), MKEK_KEY(mkek), MKEK_KEY_SIZE + MKEK_KEY_CS_SIZE);
if (ret != 0) {
return PICOKEY_EXEC_ERROR;
}
uint32_t mkek_checksum = 0;
memcpy(&mkek_checksum, MKEK_CHECKSUM(mkek), sizeof(mkek_checksum));
if (crc32c(MKEK_KEY(mkek), MKEK_KEY_SIZE) != mkek_checksum) {
return PICOKEY_WRONG_DKEK;
}
if (otp_key_1) {
mkek_masked(mkek, otp_key_1);
}
}
return PICOKEY_OK;
}
void release_mkek(uint8_t *mkek) {
mbedtls_platform_zeroize(mkek, MKEK_SIZE);
}
int mkek_decrypt(uint8_t *data, uint16_t len) {
int r;
uint8_t mkek[MKEK_SIZE + 4];
if ((r = load_mkek(mkek)) != PICOKEY_OK) {
return r;
}
r = aes_decrypt_cfb_256(MKEK_KEY(mkek), MKEK_IV(mkek), data, len);
release_mkek(mkek);
return r;
}

46
src/fido/kek.h
View File

@@ -1,46 +0,0 @@
/*
* This file is part of the Pico Fido distribution (https://github.com/polhenarejos/pico-fido).
* Copyright (c) 2022 Pol Henarejos.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License as published by
* the Free Software Foundation, version 3.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <https://www.gnu.org/licenses/>.
*/
#ifndef _KEK_H_
#define _KEK_H_
#include "crypto_utils.h"
#if defined(ENABLE_EMULATION) || defined(ESP_PLATFORM)
#include <stdbool.h>
#endif
extern int load_mkek(uint8_t *);
extern int store_mkek(const uint8_t *);
extern void init_mkek(void);
extern void release_mkek(uint8_t *);
extern int mkek_encrypt(uint8_t *data, uint16_t len);
extern int mkek_decrypt(uint8_t *data, uint16_t len);
#define MKEK_IV_SIZE (IV_SIZE)
#define MKEK_KEY_SIZE (32)
#define MKEK_KEY_CS_SIZE (4)
#define MKEK_SIZE (MKEK_IV_SIZE + MKEK_KEY_SIZE + MKEK_KEY_CS_SIZE)
#define MKEK_IV(p) (p)
#define MKEK_KEY(p) (MKEK_IV(p) + MKEK_IV_SIZE)
#define MKEK_CHECKSUM(p) (MKEK_KEY(p) + MKEK_KEY_SIZE)
#define DKEK_KEY_SIZE (32)
extern uint8_t mkek_mask[MKEK_KEY_SIZE];
extern bool has_mkek_mask;
#endif