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Adding support for CBOR CONFIG.

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This first support includes a vendor command for encrypting the key device with external key.

Signed-off-by: Pol Henarejos <pol.henarejos@cttc.es>
This commit is contained in:
Pol Henarejos 2022-10-17 17:37:39 +02:00
parent 69eef7651c
commit 4425722a71
No known key found for this signature in database
GPG Key ID: C0095B7870A4CCD3
6 changed files with 245 additions and 3 deletions
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1
CMakeLists.txt
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@ -62,6 +62,7 @@ target_sources(pico_fido PUBLIC
${CMAKE_CURRENT_LIST_DIR}/src/fido/cbor_get_assertion.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/cbor_selection.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/cbor_cred_mgmt.c
${CMAKE_CURRENT_LIST_DIR}/src/fido/cbor_config.c
)
set(HSM_DRIVER "hid")
include(pico-hsm-sdk/pico_hsm_sdk_import.cmake)

3
src/fido/cbor.c
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@ -36,6 +36,7 @@ int cbor_get_assertion(const uint8_t *data, size_t len, bool next);
int cbor_get_next_assertion(const uint8_t *data, size_t len);
int cbor_selection();
int cbor_cred_mgmt(const uint8_t *data, size_t len);
int cbor_config(const uint8_t *data, size_t len);
const uint8_t aaguid[16] = {0x89, 0xFB, 0x94, 0xB7, 0x06, 0xC9, 0x36, 0x73, 0x9B, 0x7E, 0x30, 0x52, 0x6D, 0x96, 0x81, 0x45}; // First 16 bytes of SHA256("Pico FIDO2")
@ -63,6 +64,8 @@ int cbor_parse(const uint8_t *data, size_t len) {
return cbor_selection();
else if (data[0] == CTAP_CREDENTIAL_MGMT)
return cbor_cred_mgmt(data + 1, len - 1);
else if (data[0] == CTAP_CONFIG)
return cbor_config(data + 1, len - 1);
return CTAP2_ERR_INVALID_CBOR;
}

4
src/fido/cbor_client_pin.c
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@ -35,8 +35,8 @@ uint8_t permissions_rp_id = 0, permission_set = 0;
uint32_t usage_timer = 0, initial_usage_time_limit = 0;
uint32_t max_usage_time_period = 600*1000;
bool needs_power_cycle = false;
mbedtls_ecdh_context hkey;
bool hkey_init = false;
static mbedtls_ecdh_context hkey;
static bool hkey_init = false;
int beginUsingPinUvAuthToken(bool userIsPresent) {
paut.user_present = userIsPresent;

228
src/fido/cbor_config.c Normal file
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@ -0,0 +1,228 @@
/*
* 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 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
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "ctap2_cbor.h"
#include "fido.h"
#include "ctap.h"
#include "bsp/board.h"
#include "files.h"
#include "apdu.h"
#include "credential.h"
#include "hsm.h"
#include "random.h"
#include "mbedtls/ecdh.h"
#include "mbedtls/chachapoly.h"
#include "mbedtls/hkdf.h"
static mbedtls_ecdh_context hkey;
static bool hkey_init = false;
int cbor_config(const uint8_t *data, size_t len) {
CborParser parser;
CborValue map;
CborError error = CborNoError;
uint64_t subcommand = 0, pinUvAuthProtocol = 0, vendorCommandId = 0;
int64_t kty = 0, alg = 0, crv = 0;
CborByteString pinUvAuthParam = {0}, vendorAutCt = {0}, kax = {0}, kay = {0};
size_t resp_size = 0;
CborEncoder encoder, mapEncoder, mapEncoder2;
CBOR_CHECK(cbor_parser_init(data, len, 0, &parser, &map));
uint64_t val_c = 1;
CBOR_PARSE_MAP_START(map, 1) {
uint64_t val_u = 0;
CBOR_FIELD_GET_UINT(val_u, 1);
if (val_c <= 1 && val_c != val_u)
CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
if (val_u < val_c)
CBOR_ERROR(CTAP2_ERR_INVALID_CBOR);
val_c = val_u + 1;
if (val_u == 0x01) {
CBOR_FIELD_GET_UINT(subcommand, 1);
}
else if (val_u == 0x02) {
uint64_t subpara = 0;
CBOR_PARSE_MAP_START(_f1, 2) {
if (subcommand == 0xff) {
CBOR_FIELD_GET_UINT(subpara, 2);
if (subpara == 0x01) {
CBOR_FIELD_GET_UINT(vendorCommandId, 2);
}
else if (subpara == 0x02) {
int64_t key = 0;
CBOR_PARSE_MAP_START(_f2, 3) {
CBOR_FIELD_GET_INT(key, 3);
if (key == 1) {
CBOR_FIELD_GET_INT(kty, 3);
}
else if (key == 3) {
CBOR_FIELD_GET_INT(alg, 3);
}
else if (key == -1) {
CBOR_FIELD_GET_INT(crv, 3);
}
else if (key == -2) {
CBOR_FIELD_GET_BYTES(kax, 3);
}
else if (key == -3) {
CBOR_FIELD_GET_BYTES(kay, 3);
}
else
CBOR_ADVANCE(3);
}
CBOR_PARSE_MAP_END(_f2, 3);
}
else if (subpara == 0x03) {
CBOR_FIELD_GET_BYTES(vendorAutCt, 2);
}
}
}
CBOR_PARSE_MAP_END(_f1, 2);
}
else if (val_u == 0x03) {
CBOR_FIELD_GET_UINT(pinUvAuthProtocol, 1);
}
else if (val_u == 0x04) { // pubKeyCredParams
CBOR_FIELD_GET_BYTES(pinUvAuthParam, 1);
}
}
CBOR_PARSE_MAP_END(map, 1);
cbor_encoder_init(&encoder, ctap_resp->init.data + 1, CTAP_MAX_PACKET_SIZE, 0);
if (subcommand == 0xff) {
if (vendorCommandId == CTAP_CONFIG_KEY_AGREEMENT) {
if (hkey_init == true)
mbedtls_ecdh_free(&hkey);
mbedtls_ecdh_init(&hkey);
mbedtls_ecdh_setup(&hkey, MBEDTLS_ECP_DP_SECP256R1);
int ret = mbedtls_ecdh_gen_public(&hkey.ctx.mbed_ecdh.grp, &hkey.ctx.mbed_ecdh.d, &hkey.ctx.mbed_ecdh.Q, random_gen, NULL);
mbedtls_mpi_lset(&hkey.ctx.mbed_ecdh.Qp.Z, 1);
if (ret != 0) {
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
hkey_init = true;
CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 1));
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01));
CBOR_CHECK(cbor_encoder_create_map(&mapEncoder, &mapEncoder2, 5));
CBOR_CHECK(cbor_encode_uint(&mapEncoder2, 1));
CBOR_CHECK(cbor_encode_uint(&mapEncoder2, 2));
CBOR_CHECK(cbor_encode_uint(&mapEncoder2, 3));
CBOR_CHECK(cbor_encode_negative_int(&mapEncoder2, -FIDO2_ALG_ECDH_ES_HKDF_256));
CBOR_CHECK(cbor_encode_negative_int(&mapEncoder2, 1));
CBOR_CHECK(cbor_encode_uint(&mapEncoder2, FIDO2_CURVE_P256));
CBOR_CHECK(cbor_encode_negative_int(&mapEncoder2, 2));
uint8_t pkey[32];
mbedtls_mpi_write_binary(&hkey.ctx.mbed_ecdh.Q.X, pkey, 32);
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, pkey, 32));
CBOR_CHECK(cbor_encode_negative_int(&mapEncoder2, 3));
mbedtls_mpi_write_binary(&hkey.ctx.mbed_ecdh.Q.Y, pkey, 32);
CBOR_CHECK(cbor_encode_byte_string(&mapEncoder2, pkey, 32));
CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &mapEncoder2));
}
else if (vendorCommandId == CTAP_CONFIG_AUT) {
if (*file_get_data(ef_keydev) == 0x01) { // Already encrypted
CBOR_ERROR(CTAP2_ERR_NOT_ALLOWED);
}
if (kax.present == false || kay.present == false || alg == 0)
CBOR_ERROR(CTAP2_ERR_MISSING_PARAMETER);
if (mbedtls_mpi_read_binary(&hkey.ctx.mbed_ecdh.Qp.X, kax.data, kax.len) != 0) {
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
if (mbedtls_mpi_read_binary(&hkey.ctx.mbed_ecdh.Qp.Y, kay.data, kay.len) != 0) {
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
mbedtls_mpi z;
mbedtls_mpi_init(&z);
int ret = mbedtls_ecdh_compute_shared(&hkey.ctx.mbed_ecdh.grp, &z, &hkey.ctx.mbed_ecdh.Qp, &hkey.ctx.mbed_ecdh.d, random_gen, NULL);
if (ret != 0) {
mbedtls_mpi_free(&z);
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
uint8_t buf[32], Qpt[65];
size_t olen = 0;
ret = mbedtls_ecp_point_write_binary(&hkey.ctx.mbed_ecdh.grp, &hkey.ctx.mbed_ecdh.Qp, MBEDTLS_ECP_PF_UNCOMPRESSED, &olen, Qpt, sizeof(Qpt));
if (ret != 0) {
mbedtls_mpi_free(&z);
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
ret = mbedtls_mpi_write_binary(&z, buf, sizeof(buf));
mbedtls_mpi_free(&z);
if (ret != 0) {
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
uint8_t key_enc[12+32];
ret = mbedtls_hkdf(mbedtls_md_info_from_type(MBEDTLS_MD_SHA256), NULL, 0, buf, sizeof(buf), Qpt, 65, key_enc, 12+32);
if (ret != 0){
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
mbedtls_chachapoly_context chatx;
mbedtls_chachapoly_init(&chatx);
mbedtls_chachapoly_setkey(&chatx, key_enc + 12);
ret = mbedtls_chachapoly_auth_decrypt(&chatx, vendorAutCt.len - 16, key_enc, Qpt, 65, vendorAutCt.data + vendorAutCt.len - 16, vendorAutCt.data, vendorAutCt.data);
mbedtls_chachapoly_free(&chatx);
mbedtls_ecdh_free(&hkey);
hkey_init = false;
if (ret != 0){
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
file_t *ef_keydev_enc = search_by_fid(EF_KEY_DEV_ENC, NULL, SPECIFY_EF);
uint8_t key_dev_enc[12+32+16];
random_gen(NULL, key_dev_enc, 12);
mbedtls_chachapoly_init(&chatx);
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));
mbedtls_chachapoly_free(&chatx);
if (ret != 0){
CBOR_ERROR(CTAP1_ERR_INVALID_PARAMETER);
}
flash_write_data_to_file(ef_keydev_enc, key_dev_enc, sizeof(key_dev_enc));
low_flash_available();
goto err; //No return
}
}
else
CBOR_ERROR(CTAP2_ERR_UNSUPPORTED_OPTION);
CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder));
resp_size = cbor_encoder_get_buffer_size(&encoder, ctap_resp->init.data + 1);
err:
CBOR_FREE_BYTE_STRING(pinUvAuthParam);
CBOR_FREE_BYTE_STRING(vendorAutCt);
CBOR_FREE_BYTE_STRING(kax);
CBOR_FREE_BYTE_STRING(kay);
if (error != CborNoError) {
if (error == CborErrorImproperValue)
return CTAP2_ERR_CBOR_UNEXPECTED_TYPE;
return error;
}
res_APDU_size = resp_size;
return 0;
}

8
src/fido/cbor_get_info.c
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@ -26,7 +26,7 @@ int cbor_get_info() {
CborEncoder encoder, mapEncoder, arrayEncoder;
CborError error = CborNoError;
cbor_encoder_init(&encoder, ctap_resp->init.data + 1, CTAP_MAX_PACKET_SIZE, 0);
CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 9));
CBOR_CHECK(cbor_encoder_create_map(&encoder, &mapEncoder, 10));
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x01));
CBOR_CHECK(cbor_encoder_create_array(&mapEncoder, &arrayEncoder, 3));
@ -79,6 +79,12 @@ int cbor_get_info() {
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x0E));
CBOR_CHECK(cbor_encode_uint(&mapEncoder, PICO_FIDO_VERSION)); // firmwareVersion
CBOR_CHECK(cbor_encode_uint(&mapEncoder, 0x15));
CBOR_CHECK(cbor_encoder_create_array(&mapEncoder, &arrayEncoder, 2));
CBOR_CHECK(cbor_encode_uint(&arrayEncoder, CTAP_CONFIG_AUT));
CBOR_CHECK(cbor_encode_uint(&arrayEncoder, CTAP_CONFIG_KEY_AGREEMENT));
CBOR_CHECK(cbor_encoder_close_container(&mapEncoder, &arrayEncoder));
CBOR_CHECK(cbor_encoder_close_container(&encoder, &mapEncoder));
err:
if (error != CborNoError)

4
src/fido/ctap.h
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@ -114,6 +114,10 @@ typedef struct {
#define CTAP_GET_NEXT_ASSERTION 0x08
#define CTAP_CREDENTIAL_MGMT 0x0A
#define CTAP_SELECTION 0x0B
#define CTAP_CONFIG 0x0D
#define CTAP_CONFIG_AUT 0x03e43f56b34285e2
#define CTAP_CONFIG_KEY_AGREEMENT 0x1831a40f04a25ed9
// Command status responses