dearsky/pico-fido
1
0
Fork 0
Code Issues 46 Pull Requests 1 Actions Packages Projects Releases 22 Wiki Activity

Migration to the new system of secure functions to derive keys based on OTP, if available, and pico_serial as a fallback. PIN is also an input vector, which defines a separated domain.

Browse Source 
PIN is used to derive encryption key, derive session key and derive verifier. From session key is derived encryption key. As a consequence, MKEK functionalities are not necessary anymore, since key device is handled by this new set directly. Some MKEK functions are left for compatibility purposes and for the silent migration to new format.  It also applies for double_hash_pin and hash_multi, which are deprecated.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2025-10-08 00:33:23 +02:00
parent 51c13b0f0b
commit 898c88dc6d
5 changed files with 134 additions and 141 deletions
Download Patch File Download Diff File Expand all files Collapse all files

40
src/fido/kek.c
View File

@@ -85,46 +85,6 @@ void release_mkek(uint8_t *mkek) {
mbedtls_platform_zeroize(mkek, MKEK_SIZE);
}
int store_mkek(const uint8_t *mkek) {
uint8_t tmp_mkek[MKEK_SIZE];
if (mkek == NULL) {
const uint8_t *rd = random_bytes_get(MKEK_IV_SIZE + MKEK_KEY_SIZE);
memcpy(tmp_mkek, rd, MKEK_IV_SIZE + MKEK_KEY_SIZE);
}
else {
memcpy(tmp_mkek, mkek, MKEK_SIZE);
}
if (otp_key_1) {
mkek_masked(tmp_mkek, otp_key_1);
}
*(uint32_t *) MKEK_CHECKSUM(tmp_mkek) = crc32c(MKEK_KEY(tmp_mkek), MKEK_KEY_SIZE);
uint8_t tmp_mkek_pin[MKEK_SIZE];
memcpy(tmp_mkek_pin, tmp_mkek, MKEK_SIZE);
file_t *tf = search_file(EF_MKEK);
if (!tf) {
release_mkek(tmp_mkek);
release_mkek(tmp_mkek_pin);
return PICOKEY_ERR_FILE_NOT_FOUND;
}
aes_encrypt_cfb_256(session_pin, MKEK_IV(tmp_mkek_pin), MKEK_KEY(tmp_mkek_pin), MKEK_KEY_SIZE + MKEK_KEY_CS_SIZE);
file_put_data(tf, tmp_mkek_pin, MKEK_SIZE);
release_mkek(tmp_mkek_pin);
low_flash_available();
release_mkek(tmp_mkek);
return PICOKEY_OK;
}
int mkek_encrypt(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_encrypt_cfb_256(MKEK_KEY(mkek), MKEK_IV(mkek), data, len);
release_mkek(mkek);
return r;
}
int mkek_decrypt(uint8_t *data, uint16_t len) {
int r;
uint8_t mkek[MKEK_SIZE + 4];