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MKEK is also stored with SO encryption.

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A copy of MKEK is also stored but encrypted with SO-PIN. Thus, we always ensure that we have an operative copy of MKEK, either with PIN and/or SO-PIN. If user resets PIN, the MKEK is loaded with SO-PIN and stored with the derived key from new PIN.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos 2022-08-12 00:41:04 +02:00
parent 84a70a1de0
commit 7b27cb7a1c
No known key found for this signature in database
GPG Key ID: C0095B7870A4CCD3
2 changed files with 50 additions and 15 deletions
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38
src/hsm/dkek.c
View File

@ -29,8 +29,8 @@
#include "mbedtls/ecdsa.h"
#include "files.h"
extern bool has_session_pin;
extern uint8_t session_pin[32];
extern bool has_session_pin, has_session_sopin;
extern uint8_t session_pin[32], session_sopin[32];
#define POLY 0xedb88320
@ -46,13 +46,26 @@ uint32_t crc32c(const uint8_t *buf, size_t len)
}
int load_mkek(uint8_t *mkek) {
if (has_session_pin == false)
if (has_session_pin == false && has_session_sopin == false)
return CCID_NO_LOGIN;
const uint8_t *pin = NULL;
if (pin == NULL && has_session_pin == true) {
file_t *tf = search_dynamic_file(EF_MKEK);
if (!tf)
return CCID_ERR_FILE_NOT_FOUND;
if (tf) {
memcpy(mkek, file_get_data(tf), MKEK_SIZE);
int ret = aes_decrypt_cfb_256(session_pin, MKEK_IV(mkek), MKEK_KEY(mkek), MKEK_KEY_SIZE+MKEK_KEY_CS_SIZE);
pin = session_pin;
}
}
if (pin == NULL && has_session_sopin == true) {
file_t *tf = search_dynamic_file(EF_MKEK_SO);
if (tf) {
memcpy(mkek, file_get_data(tf), MKEK_SIZE);
pin = session_sopin;
}
}
if (pin == NULL) //Should never happen
return CCID_EXEC_ERROR;
int ret = aes_decrypt_cfb_256(pin, MKEK_IV(mkek), MKEK_KEY(mkek), MKEK_KEY_SIZE+MKEK_KEY_CS_SIZE);
if (ret != 0)
return CCID_EXEC_ERROR;
if (crc32c(MKEK_KEY(mkek), MKEK_KEY_SIZE) != *(uint32_t*)MKEK_CHECKSUM(mkek))
@ -73,7 +86,7 @@ void release_mkek(uint8_t *mkek) {
}
int store_mkek(const uint8_t *mkek) {
if (has_session_pin == false)
if (has_session_pin == false && has_session_sopin == false)
return CCID_NO_LOGIN;
uint8_t tmp_mkek[MKEK_SIZE];
if (mkek == NULL) {
@ -82,12 +95,21 @@ int store_mkek(const uint8_t *mkek) {
}
else
memcpy(tmp_mkek, mkek, MKEK_SIZE);
*(uint32_t*)MKEK_CHECKSUM(tmp_mkek) = crc32c(MKEK_KEY(tmp_mkek), MKEK_KEY_SIZE);
if (has_session_pin) {
file_t *tf = search_dynamic_file(EF_MKEK);
if (!tf)
return CCID_ERR_FILE_NOT_FOUND;
*(uint32_t*)MKEK_CHECKSUM(tmp_mkek) = crc32c(MKEK_KEY(tmp_mkek), MKEK_KEY_SIZE);
aes_encrypt_cfb_256(session_pin, MKEK_IV(tmp_mkek), MKEK_KEY(tmp_mkek), MKEK_KEY_SIZE+MKEK_KEY_CS_SIZE);
flash_write_data_to_file(tf, tmp_mkek, MKEK_SIZE);
}
if (has_session_sopin) {
file_t *tf = search_dynamic_file(EF_MKEK_SO);
if (!tf)
return CCID_ERR_FILE_NOT_FOUND;
aes_encrypt_cfb_256(session_sopin, MKEK_IV(tmp_mkek), MKEK_KEY(tmp_mkek), MKEK_KEY_SIZE+MKEK_KEY_CS_SIZE);
flash_write_data_to_file(tf, tmp_mkek, MKEK_SIZE);
}
low_flash_available();
release_mkek(tmp_mkek);
return CCID_OK;

15
src/hsm/sc_hsm.c
View File

@ -644,6 +644,16 @@ static int cmd_reset_retry() {
flash_write_data_to_file(file_pin1, dhash, sizeof(dhash));
if (pin_reset_retries(file_pin1, true) != CCID_OK)
return SW_MEMORY_FAILURE();
uint8_t mkek[MKEK_SIZE];
int r = load_mkek(mkek); //loads the MKEK with SO pin
if (r != CCID_OK)
return SW_EXEC_ERROR();
hash_multi(apdu.data+(apdu.nc-newpin_len), newpin_len, session_pin);
has_session_pin = true;
r = store_mkek(mkek);
release_mkek(mkek);
if (r != CCID_OK)
return SW_EXEC_ERROR();
low_flash_available();
return SW_OK();
}
@ -656,6 +666,8 @@ static int cmd_reset_retry() {
uint16_t r = check_pin(file_sopin, apdu.data, 8);
if (r != 0x9000)
return r;
has_session_sopin = true;
hash_multi(apdu.data, 8, session_sopin);
}
else if (P1(apdu) == 0x3) {
if (!has_session_sopin)
@ -696,6 +708,7 @@ static int cmd_initialize() {
if (apdu.nc > 0) {
initialize_flash(true);
scan_all();
has_session_pin = has_session_sopin = false;
uint16_t tag = 0x0;
uint8_t *tag_data = NULL, *p = NULL, *kds = NULL, *dkeks = NULL;
size_t tag_len = 0;
@ -711,6 +724,7 @@ static int cmd_initialize() {
double_hash_pin(tag_data, tag_len, dhash+1);
flash_write_data_to_file(file_pin1, dhash, sizeof(dhash));
hash_multi(tag_data, tag_len, session_pin);
has_session_pin = true;
}
}
else if (tag == 0x82) { //sopin pin
@ -794,7 +808,6 @@ static int cmd_initialize() {
return SW_EXEC_ERROR();
}
/* When initialized, it has all credentials */
has_session_pin = true;
isUserAuthenticated = true;
low_flash_available();
}