dearsky/pico-hsm
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Adding Secure Lock to lock the device with a random 256 bit key.

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This is an extra layer of security to avoid brute force attacks if PIN is too weak.
At every hard reset (on device plug), the device must be unlocked prior any other command. Once unlocked, the device can be used as usual.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos
2022-10-31 15:09:54 +01:00
parent eda8b53949
commit 00279da8d5
5 changed files with 215 additions and 4 deletions
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20
src/hsm/kek.c
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@@ -27,10 +27,13 @@
#include "mbedtls/cmac.h"
#include "mbedtls/rsa.h"
#include "mbedtls/ecdsa.h"
#include "mbedtls/chachapoly.h"
#include "files.h"
extern bool has_session_pin, has_session_sopin;
extern uint8_t session_pin[32], session_sopin[32];
uint8_t mkek_mask[MKEK_KEY_SIZE];
bool has_mkek_mask = false;
#define POLY 0xedb88320
@@ -65,6 +68,12 @@ int load_mkek(uint8_t *mkek) {
}
if (pin == NULL) //Should never happen
return CCID_EXEC_ERROR;
if (has_mkek_mask) {
for (int i = 0; i < MKEK_KEY_SIZE; i++) {
MKEK_KEY(mkek)[i] ^= mkek_mask[i];
}
}
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;
@@ -73,6 +82,17 @@ int load_mkek(uint8_t *mkek) {
return CCID_OK;
}
mse_t mse = {.init = false};
int mse_decrypt_ct(uint8_t *data, size_t len) {
mbedtls_chachapoly_context chatx;
mbedtls_chachapoly_init(&chatx);
mbedtls_chachapoly_setkey(&chatx, mse.key_enc + 12);
int ret = mbedtls_chachapoly_auth_decrypt(&chatx, len - 16, mse.key_enc, mse.Qpt, 65, data + len - 16, data, data);
mbedtls_chachapoly_free(&chatx);
return ret;
}
int load_dkek(uint8_t id, uint8_t *dkek) {
file_t *tf = search_dynamic_file(EF_DKEK+id);
if (!tf)