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atecc608a_se.c
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atecc608a_se.c
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/**
* \file atecc608a_se.c
* \brief Secure element driver implementation for ATECC508A and ATECC509A.
*/
/*
* Copyright (C) 2019, ARM Limited, All Rights Reserved
* SPDX-License-Identifier: Apache-2.0
*
* Licensed under the Apache License, Version 2.0 (the "License"); you may
* not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include "atecc608a_se.h"
#include "atca_helpers.h"
#include "psa/crypto.h"
#ifdef DEBUG_PRINT
#include <stdio.h>
#endif
#include <stdbool.h>
#include <stdint.h>
/* Uncomment to print results on success */
//#define DEBUG_PRINT
/** This macro checks if the result of an `expression` is equal to an
* `expected` value and sets a `status` variable of type `psa_status_t` to
* `PSA_SUCCESS`. If they are not equal, the `status` is set to
* `psa_error instead`, and the code jumps to the `exit` label. */
#define ASSERT_STATUS(expression, expected, psa_error) \
do \
{ \
ATCA_STATUS ASSERT_result = (expression); \
ATCA_STATUS ASSERT_expected = (expected); \
if ((ASSERT_result) != (ASSERT_expected)) \
{ \
status = (psa_error); \
goto exit; \
} \
status = PSA_SUCCESS; \
} while(0)
/** Check if an ATCA operation is successful, translate the error otherwise. */
#define ASSERT_SUCCESS(expression) ASSERT_STATUS(expression, ATCA_SUCCESS, \
atecc608a_to_psa_error(ASSERT_result))
/** Does the same as the macro above, but without the error translation and for
* the PSA return code - PSA_SUCCESS.*/
#define ASSERT_SUCCESS_PSA(expression) ASSERT_STATUS(expression, PSA_SUCCESS, \
ASSERT_result)
static ATCAIfaceCfg atca_iface_config = {
.iface_type = ATCA_I2C_IFACE,
.devtype = ATECC608A,
.atcai2c.slave_address = 0x6A,
.atcai2c.bus = 2,
.atcai2c.baud = 400000,
.wake_delay = 1500,
.rx_retries = 20,
};
psa_status_t atecc608a_to_psa_error(ATCA_STATUS ret)
{
switch (ret) {
case ATCA_SUCCESS:
case ATCA_RX_NO_RESPONSE:
case ATCA_WAKE_SUCCESS:
return PSA_SUCCESS;
case ATCA_BAD_PARAM:
case ATCA_INVALID_ID:
return PSA_ERROR_INVALID_ARGUMENT;
case ATCA_ASSERT_FAILURE:
return PSA_ERROR_CORRUPTION_DETECTED;
case ATCA_SMALL_BUFFER:
return PSA_ERROR_BUFFER_TOO_SMALL;
case ATCA_RX_CRC_ERROR:
case ATCA_RX_FAIL:
case ATCA_STATUS_CRC:
case ATCA_RESYNC_WITH_WAKEUP:
case ATCA_PARITY_ERROR:
case ATCA_TX_TIMEOUT:
case ATCA_RX_TIMEOUT:
case ATCA_TOO_MANY_COMM_RETRIES:
case ATCA_COMM_FAIL:
case ATCA_TIMEOUT:
case ATCA_TX_FAIL:
case ATCA_NO_DEVICES:
return PSA_ERROR_COMMUNICATION_FAILURE;
case ATCA_UNIMPLEMENTED:
return PSA_ERROR_NOT_SUPPORTED;
case ATCA_ALLOC_FAILURE:
return PSA_ERROR_INSUFFICIENT_MEMORY;
case ATCA_BAD_OPCODE:
case ATCA_CONFIG_ZONE_LOCKED:
case ATCA_DATA_ZONE_LOCKED:
case ATCA_NOT_LOCKED:
case ATCA_WAKE_FAILED:
case ATCA_STATUS_UNKNOWN:
case ATCA_STATUS_ECC:
case ATCA_STATUS_SELFTEST_ERROR:
case ATCA_CHECKMAC_VERIFY_FAILED:
case ATCA_PARSE_ERROR:
case ATCA_FUNC_FAIL:
case ATCA_GEN_FAIL:
case ATCA_EXECUTION_ERROR:
case ATCA_HEALTH_TEST_ERROR:
case ATCA_INVALID_SIZE:
default:
return PSA_ERROR_HARDWARE_FAILURE;
}
}
/* The driver works with pubkeys as concatenated x and y values, and the PSA
* format for pubkeys is 0x04 + x + y. Always use a pubkey buffer in PSA
* format, with enough space for the PSA format. To translate this buffer for
* use with cryptoauthlib, use pubkey_for_driver(). To ensure the buffer is in
* valid PSA format after cryptoauthlib operations, call set_psa_pubkey_prefix(). */
static uint8_t *pubkey_for_driver(uint8_t *data)
{
return &data[1];
}
static void set_psa_pubkey_prefix(uint8_t *data)
{
data[0] = 0x4;
}
static bool is_public_key_slot(uint16_t key_slot)
{
/* Keys 8 to 15 can store public keys. Slots 1-7 are too small. */
return (key_slot >= 8 && key_slot <= 15);
}
psa_status_t atecc608a_init()
{
return atecc608a_to_psa_error(atcab_init(&atca_iface_config));
}
psa_status_t atecc608a_deinit()
{
return atecc608a_to_psa_error(atcab_release());
}
static psa_status_t atecc608a_export_public_key(psa_drv_se_context_t *drv_context,
psa_key_slot_number_t key,
uint8_t *p_data,
size_t data_size,
size_t *p_data_length)
{
const size_t key_data_len = PSA_KEY_EXPORT_MAX_SIZE(
PSA_KEY_TYPE_ECC_PUBLIC_KEY(
PSA_ECC_CURVE_SECP256R1),
256);
const uint16_t slot = key;
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
(void) drv_context;
if (data_size < key_data_len) {
return PSA_ERROR_BUFFER_TOO_SMALL;
}
ASSERT_SUCCESS_PSA(atecc608a_init());
ASSERT_SUCCESS(atcab_get_pubkey(slot, pubkey_for_driver(p_data)));
set_psa_pubkey_prefix(p_data);
*p_data_length = key_data_len;
#ifdef DEBUG_PRINT
printf("atecc608a_export_key - pubkey size %d:\n", *p_data_length);
atcab_printbin_sp(p_data, *p_data_length);
#endif
exit:
atecc608a_deinit();
return status;
}
static psa_status_t atecc608a_import_public_key(
psa_drv_se_context_t *drv_context,
psa_key_slot_number_t key_slot,
const psa_key_attributes_t *attributes,
const uint8_t *data,
size_t data_length,
size_t *bits)
{
const uint16_t key_id = key_slot;
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
psa_key_type_t type = psa_get_key_type(attributes);
psa_algorithm_t alg = psa_get_key_algorithm(attributes);
(void) drv_context;
if (!is_public_key_slot(key_id)) {
return PSA_ERROR_INVALID_ARGUMENT;
}
/* Check if the key has a size of 65 {0x04, X, Y}. */
if (data_length != PSA_KEY_EXPORT_MAX_SIZE(PSA_KEY_TYPE_ECC_PUBLIC_KEY(
PSA_ECC_CURVE_SECP256R1),
256)) {
return PSA_ERROR_INVALID_ARGUMENT;
}
if (type != PSA_KEY_TYPE_ECC_PUBLIC_KEY(PSA_ECC_CURVE_SECP256R1)) {
return PSA_ERROR_NOT_SUPPORTED;
}
/* The driver can only do randomized ECDSA on SHA-256 */
if (alg != PSA_ALG_ECDSA(PSA_ALG_SHA_256) && alg != PSA_ALG_ECDSA_ANY) {
return PSA_ERROR_NOT_SUPPORTED;
}
ASSERT_SUCCESS_PSA(atecc608a_init());
ASSERT_SUCCESS(atcab_write_pubkey(key_id, pubkey_for_driver((uint8_t *) data)));
if (bits != NULL) {
*bits = 256;
}
exit:
atecc608a_deinit();
return status;
}
static psa_status_t atecc608a_generate_key(
psa_drv_se_context_t *drv_context,
psa_key_slot_number_t key_slot,
const psa_key_attributes_t *attributes,
uint8_t *pubkey, size_t pubkey_size, size_t *pubkey_length)
{
const uint16_t key_id = key_slot;
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
psa_key_type_t type = psa_get_key_type(attributes);
size_t bits = psa_get_key_bits(attributes);
(void) drv_context;
if (type != PSA_KEY_TYPE_ECC_KEY_PAIR(PSA_ECC_CURVE_SECP256R1)) {
return PSA_ERROR_NOT_SUPPORTED;
}
if (bits != PSA_BYTES_TO_BITS(ATCA_PRIV_KEY_SIZE)) {
return PSA_ERROR_NOT_SUPPORTED;
}
if (pubkey != NULL && pubkey_size < 1 + ATCA_PUB_KEY_SIZE) {
return PSA_ERROR_BUFFER_TOO_SMALL;
}
ASSERT_SUCCESS_PSA(atecc608a_init());
if (pubkey != NULL) {
ASSERT_SUCCESS(atcab_genkey(key_id, pubkey_for_driver(pubkey)));
set_psa_pubkey_prefix(pubkey);
} else {
ASSERT_SUCCESS(atcab_genkey(key_id, NULL));
}
*pubkey_length = 1 + ATCA_PUB_KEY_SIZE;
exit:
atecc608a_deinit();
return status;
}
static psa_status_t atecc608a_asymmetric_sign(psa_drv_se_context_t *drv_context,
psa_key_slot_number_t key_slot,
psa_algorithm_t alg,
const uint8_t *p_hash,
size_t hash_length,
uint8_t *p_signature,
size_t signature_size,
size_t *p_signature_length)
{
const uint16_t key_id = key_slot;
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
(void) drv_context;
/* The driver can only do randomized ECDSA on SHA-256 */
if (alg != PSA_ALG_ECDSA(PSA_ALG_SHA_256) && alg != PSA_ALG_ECDSA_ANY) {
return PSA_ERROR_NOT_SUPPORTED;
}
if (hash_length != PSA_HASH_SIZE(PSA_ALG_SHA_256)) {
/* The driver only supports signing things of length 32. */
return PSA_ERROR_NOT_SUPPORTED;
}
if (signature_size < ATCA_SIG_SIZE) {
return PSA_ERROR_BUFFER_TOO_SMALL;
}
ASSERT_SUCCESS_PSA(atecc608a_init());
/* Signature will be returned here. Format is R and S integers in
* big-endian format. 64 bytes for P256 curve. */
ASSERT_SUCCESS(atcab_sign(key_id, p_hash, p_signature));
*p_signature_length = ATCA_SIG_SIZE;
#ifdef DEBUG_PRINT
printf("atecc608a_asymmetric_sign - signature size %d:\n", *p_signature_length);
atcab_printbin_sp(p_signature, *p_signature_length);
#endif
exit:
atecc608a_deinit();
return status;
}
psa_status_t atecc608a_asymmetric_verify(psa_drv_se_context_t *drv_context,
psa_key_slot_number_t key_slot,
psa_algorithm_t alg,
const uint8_t *p_hash,
size_t hash_length,
const uint8_t *p_signature,
size_t signature_length)
{
const uint16_t key_id = key_slot;
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
bool is_verified = false;
(void) drv_context;
if (!is_public_key_slot(key_id)) {
return PSA_ERROR_INVALID_ARGUMENT;
}
/* The driver can only do randomized ECDSA on SHA-256 */
if (alg != PSA_ALG_ECDSA(PSA_ALG_SHA_256) && alg != PSA_ALG_ECDSA_ANY) {
return PSA_ERROR_NOT_SUPPORTED;
}
if (hash_length != PSA_HASH_SIZE(PSA_ALG_SHA_256)) {
/* The driver only supports hashes of length 32. */
return PSA_ERROR_NOT_SUPPORTED;
}
if (signature_length != ATCA_SIG_SIZE) {
/* The driver only supports signatures of length 64. */
return PSA_ERROR_INVALID_SIGNATURE;
}
ASSERT_SUCCESS_PSA(atecc608a_init());
ASSERT_SUCCESS(atcab_verify_stored(p_hash, p_signature, key_id, &is_verified));
exit:
atecc608a_deinit();
return status;
}
psa_status_t atecc608a_write(uint16_t slot, size_t offset, const uint8_t *data, size_t length)
{
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
ASSERT_SUCCESS_PSA(atecc608a_init());
ASSERT_SUCCESS(atcab_write_bytes_zone(ATCA_ZONE_DATA, slot, offset, data, length));
exit:
atecc608a_deinit();
return status;
}
psa_status_t atecc608a_read(uint16_t slot, size_t offset, uint8_t *data, size_t length)
{
psa_status_t status = PSA_ERROR_GENERIC_ERROR;
ASSERT_SUCCESS_PSA(atecc608a_init());
ASSERT_SUCCESS(atcab_read_bytes_zone(ATCA_ZONE_DATA, slot, offset, data, length));
exit:
atecc608a_deinit();
return status;
}
static psa_status_t atecc608a_validate_slot_number(
psa_drv_se_context_t *drv_context,
const psa_key_attributes_t *attributes,
psa_key_creation_method_t method,
psa_key_slot_number_t key_slot)
{
psa_key_type_t type = psa_get_key_type(attributes);
(void) drv_context;
(void) method;
if (PSA_KEY_TYPE_IS_ECC_KEY_PAIR(type)) {
if (key_slot <= 15) {
return PSA_SUCCESS;
}
} else if (PSA_KEY_TYPE_IS_ECC_PUBLIC_KEY(type)) {
if (key_slot >= 8 && key_slot <= 15) {
return PSA_SUCCESS;
}
}
return PSA_ERROR_NOT_SUPPORTED;
}
static psa_status_t atecc608a_allocate_key(
psa_drv_se_context_t *drv_context,
void *persistent_data,
const psa_key_attributes_t *attributes,
psa_key_creation_method_t method,
psa_key_slot_number_t *key_slot)
{
(void) drv_context;
(void) persistent_data;
(void) attributes;
(void) method;
(void) key_slot;
/* TODO - this function is not implemented yet. It will contain
persistent data handling to ensure that a single slot
will not be allocated twice. */
return PSA_SUCCESS;
}
static psa_drv_se_asymmetric_t atecc608a_asymmetric = {
.p_sign = atecc608a_asymmetric_sign,
.p_verify = atecc608a_asymmetric_verify,
.p_encrypt = 0,
.p_decrypt = 0,
};
static psa_drv_se_key_management_t atecc608a_key_management = {
/* So far there is no public key import function in the API, so use this instead */
.p_allocate = atecc608a_allocate_key,
.p_validate_slot_number = atecc608a_validate_slot_number,
.p_import = atecc608a_import_public_key,
.p_generate = atecc608a_generate_key,
.p_destroy = 0,
.p_export = 0,
.p_export_public = atecc608a_export_public_key,
};
psa_drv_se_t atecc608a_drv_info = {
.key_management = &atecc608a_key_management,
.mac = NULL,
.cipher = NULL,
.asymmetric = &atecc608a_asymmetric,
.aead = NULL,
.derivation = NULL,
.hal_version = PSA_DRV_SE_HAL_VERSION
};