dearsky/pico-fido
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Added unlock config command to unlock the device at every boot with an external key.

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Signed-off-by: trocotronic <trocotronic@redyc.com>
This commit is contained in:
Pol Henarejos
2022-10-19 16:39:13 +02:00
parent 2c125e76eb
commit f213854f8b
2 changed files with 48 additions and 20 deletions
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55
src/fido/cbor_config.c
View File

@@ -16,6 +16,7 @@
* along with this program. If not, see <http://www.gnu.org/licenses/>. * along with this program. If not, see <http://www.gnu.org/licenses/>.
*/ */
#include "common.h"
#include "ctap2_cbor.h" #include "ctap2_cbor.h"
#include "fido.h" #include "fido.h"
#include "ctap.h" #include "ctap.h"
@@ -32,6 +33,8 @@
static mbedtls_ecdh_context hkey; static mbedtls_ecdh_context hkey;
static bool hkey_init = false; static bool hkey_init = false;
extern uint8_t keydev_dec[32];
extern bool has_keydev_dec;
int cbor_config(const uint8_t *data, size_t len) { int cbor_config(const uint8_t *data, size_t len) {
CborParser parser; CborParser parser;
@@ -138,12 +141,9 @@ int cbor_config(const uint8_t *data, size_t len) {
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, pkey, 32)); CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, pkey, 32));
CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2)); CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2));
} }
else if (vendorCommandId == CTAP_CONFIG_AUT) { else if (vendorCommandId == CTAP_CONFIG_AUT || vendorCommandId == CTAP_CONFIG_UNLOCK) {
if (vendorCommandId == CTAP_CONFIG_AUT && !file_has_data(ef_keydev))
if (*file_get_data(ef_keydev) == 0x01) { // Already encrypted
CBOR_ERROR(CTAP2_ERR_NOT_ALLOWED); CBOR_ERROR(CTAP2_ERR_NOT_ALLOWED);
}
if (kax.present == false || kay.present == false || alg == 0) if (kax.present == false || kay.present == false || alg == 0)
CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER); CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
@@ -190,22 +190,43 @@ int cbor_config(const uint8_t *data, size_t len) {
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
} }
file_t *ef_keydev_enc = search_by_fid(EF_KEY_DEV_ENC, NULL, SPECIFY_EF); if (vendorCommandId == CTAP_CONFIG_AUT) {
uint8_t key_dev_enc[12+32+16]; uint8_t key_dev_enc[12+32+16];
random_gen(NULL, key_dev_enc, 12); random_gen(NULL, key_dev_enc, 12);
mbedtls_chachapoly_init(&chatx); mbedtls_chachapoly_init(&chatx);
mbedtls_chachapoly_setkey(&chatx, vendorAutCt.data); mbedtls_chachapoly_setkey(&chatx, vendorAutCt.data);
ret = mbedtls_chachapoly_encrypt_and_tag(&chatx, file_get_size(ef_keydev), key_dev_enc, NULL, 0, file_get_data(ef_keydev), key_dev_enc + 12, key_dev_enc + 12 + file_get_size(ef_keydev)); ret = mbedtls_chachapoly_encrypt_and_tag(&chatx, file_get_size(ef_keydev), key_dev_enc, NULL, 0, file_get_data(ef_keydev), key_dev_enc + 12, key_dev_enc + 12 + file_get_size(ef_keydev));
mbedtls_chachapoly_free(&chatx); mbedtls_chachapoly_free(&chatx);
if (ret != 0){ if (ret != 0){
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER); CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
flash_write_data_to_file(ef_keydev_enc, key_dev_enc, sizeof(key_dev_enc));
mbedtls_platform_zeroize(key_dev_enc, sizeof(key_dev_enc));
flash_write_data_to_file(ef_keydev, key_dev_enc, file_get_size(ef_keydev)); // Overwrite ef with 0
flash_write_data_to_file(ef_keydev, NULL, 0); // Set ef to 0 bytes
low_flash_available();
} }
else if (vendorCommandId == CTAP_CONFIG_UNLOCK) {
if (!file_has_data(ef_keydev_enc))
CBOR_ERROR(CTAP2_ERR_INTEGRITY_FAILURE);
flash_write_data_to_file(ef_keydev_enc, key_dev_enc, sizeof(key_dev_enc)); uint8_t *keyenc = file_get_data(ef_keydev_enc);
low_flash_available(); size_t keyenc_len = file_get_size(ef_keydev_enc);
mbedtls_chachapoly_init(&chatx);
mbedtls_chachapoly_setkey(&chatx, vendorAutCt.data);
ret = mbedtls_chachapoly_auth_decrypt(&chatx, sizeof(keydev_dec), keyenc, NULL, 0, keyenc + keyenc_len - 16, keyenc + 12, keydev_dec);
mbedtls_chachapoly_free(&chatx);
if (ret != 0){
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
has_keydev_dec = true;
}
goto err; //No return goto err; //No return
} }
else {
CBOR_ERROR(CTAP2_ERR_INVALID_SUBCOMMAND);
}
} }
else else
CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION); CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION);

13
src/fido/fido.c
View File

@@ -39,6 +39,9 @@ int fido_unload();
pinUvAuthToken_t paut = {0}; pinUvAuthToken_t paut = {0};
uint8_t keydev_dec[32];
bool has_keydev_dec = false;
const uint8_t fido_aid[] = { const uint8_t fido_aid[] = {
8, 8,
0xA0, 0x00, 0x00, 0x06, 0x47, 0x2F, 0x00, 0x01 0xA0, 0x00, 0x00, 0x06, 0x47, 0x2F, 0x00, 0x01
@@ -117,9 +120,12 @@ int x509_create_cert(mbedtls_ecdsa_context *ecdsa, uint8_t *buffer, size_t buffe
} }
int load_keydev(uint8_t *key) { int load_keydev(uint8_t *key) {
if (!ef_keydev || file_get_size(ef_keydev) == 0) if (has_keydev_dec == false && !file_has_data(ef_keydev))
return CCID_ERR_MEMORY_FATAL; return CCID_ERR_MEMORY_FATAL;
memcpy(key, file_get_data(ef_keydev), file_get_size(ef_keydev)); if (has_keydev_dec == true)
memcpy(key, keydev_dec, sizeof(keydev_dec));
else
memcpy(key, file_get_data(ef_keydev), file_get_size(ef_keydev));
//return mkek_decrypt(key, file_get_size(ef_keydev)); //return mkek_decrypt(key, file_get_size(ef_keydev));
return CCID_OK; return CCID_OK;
} }
@@ -201,8 +207,9 @@ int derive_key(const uint8_t *app_id, bool new_key, uint8_t *key_handle, int cur
int scan_files(bool core1) { int scan_files(bool core1) {
ef_keydev = search_by_fid(EF_KEY_DEV, NULL, SPECIFY_EF); ef_keydev = search_by_fid(EF_KEY_DEV, NULL, SPECIFY_EF);
ef_keydev_enc = search_by_fid(EF_KEY_DEV_ENC, NULL, SPECIFY_EF);
if (ef_keydev) { if (ef_keydev) {
if (!file_has_data(ef_keydev)) { if (!file_has_data(ef_keydev) && !file_has_data(ef_keydev_enc)) {
printf("KEY DEVICE is empty. Generating SECP256R1 curve..."); printf("KEY DEVICE is empty. Generating SECP256R1 curve...");
mbedtls_ecdsa_context ecdsa; mbedtls_ecdsa_context ecdsa;
mbedtls_ecdsa_init(&ecdsa); mbedtls_ecdsa_init(&ecdsa);