esp-idf/components/esp32c3/esp_ds.c

230 lines
6.4 KiB
C
Raw Normal View History

// Copyright 2020 Espressif Systems (Shanghai) PTE LTD
//
// 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 <stdlib.h>
#include <string.h>
#include <assert.h>
#include "freertos/FreeRTOS.h"
#include "freertos/task.h"
#include "driver/periph_ctrl.h"
#include "esp_crypto_lock.h"
#include "hal/ds_hal.h"
#include "hal/hmac_hal.h"
#include "esp32c3/rom/digital_signature.h"
#include "esp_ds.h"
struct esp_ds_context {
const esp_ds_data_t *data;
};
/**
* The vtask delay \c esp_ds_sign() is using while waiting for completion of the signing operation.
*/
#define ESP_DS_SIGN_TASK_DELAY_MS 10
#define RSA_LEN_MAX 127
/*
* esp_digital_signature_length_t is used in esp_ds_data_t in contrast to ets_ds_data_t, where unsigned is used.
* Check esp_digital_signature_length_t's width here because it's converted to unsigned using raw casts.
*/
_Static_assert(sizeof(esp_digital_signature_length_t) == sizeof(unsigned),
"The size of esp_digital_signature_length_t and unsigned has to be the same");
/*
* esp_ds_data_t is used in the encryption function but casted to ets_ds_data_t.
* Check esp_ds_data_t's width here because it's converted using raw casts.
*/
_Static_assert(sizeof(esp_ds_data_t) == sizeof(ets_ds_data_t),
"The size of esp_ds_data_t and ets_ds_data_t has to be the same");
static void ds_acquire_enable(void)
{
esp_crypto_ds_lock_acquire();
// We also enable SHA and HMAC here. SHA is used by HMAC, HMAC is used by DS.
periph_module_enable(PERIPH_HMAC_MODULE);
periph_module_enable(PERIPH_SHA_MODULE);
periph_module_enable(PERIPH_DS_MODULE);
hmac_hal_start();
}
static void ds_disable_release(void)
{
ds_hal_finish();
periph_module_disable(PERIPH_DS_MODULE);
periph_module_disable(PERIPH_SHA_MODULE);
periph_module_disable(PERIPH_HMAC_MODULE);
esp_crypto_ds_lock_release();
}
esp_err_t esp_ds_sign(const void *message,
const esp_ds_data_t *data,
hmac_key_id_t key_id,
void *signature)
{
// Need to check signature here, otherwise the signature is only checked when the signing has finished and fails
// but the signing isn't uninitialized and the mutex is still locked.
if (!signature) {
return ESP_ERR_INVALID_ARG;
}
esp_ds_context_t *context;
esp_err_t result = esp_ds_start_sign(message, data, key_id, &context);
if (result != ESP_OK) {
return result;
}
while (esp_ds_is_busy())
vTaskDelay(ESP_DS_SIGN_TASK_DELAY_MS / portTICK_PERIOD_MS);
return esp_ds_finish_sign(signature, context);
}
esp_err_t esp_ds_start_sign(const void *message,
const esp_ds_data_t *data,
hmac_key_id_t key_id,
esp_ds_context_t **esp_ds_ctx)
{
if (!message || !data || !esp_ds_ctx) {
return ESP_ERR_INVALID_ARG;
}
if (key_id >= HMAC_KEY_MAX) {
return ESP_ERR_INVALID_ARG;
}
if (!(data->rsa_length == ESP_DS_RSA_1024
|| data->rsa_length == ESP_DS_RSA_2048
|| data->rsa_length == ESP_DS_RSA_3072)) {
return ESP_ERR_INVALID_ARG;
}
ds_acquire_enable();
// initiate hmac
uint32_t conf_error = hmac_hal_configure(HMAC_OUTPUT_DS, key_id);
if (conf_error) {
ds_disable_release();
return ESP32C3_ERR_HW_CRYPTO_DS_HMAC_FAIL;
}
ds_hal_start();
// check encryption key from HMAC
ds_key_check_t key_check_result = ds_hal_check_decryption_key();
if (key_check_result != DS_KEY_INPUT_OK) {
ds_disable_release();
return ESP32C3_ERR_HW_CRYPTO_DS_INVALID_KEY;
}
esp_ds_context_t *context = malloc(sizeof(esp_ds_context_t));
if (!context) {
ds_disable_release();
return ESP_ERR_NO_MEM;
}
size_t rsa_len = (data->rsa_length + 1) * 4;
ds_hal_write_private_key_params(data->c);
ds_hal_configure_iv(data->iv);
ds_hal_write_message(message, rsa_len);
// initiate signing
ds_hal_start_sign();
context->data = data;
*esp_ds_ctx = context;
return ESP_OK;
}
bool esp_ds_is_busy(void)
{
return ds_hal_busy();
}
esp_err_t esp_ds_finish_sign(void *signature, esp_ds_context_t *esp_ds_ctx)
{
if (!signature || !esp_ds_ctx) {
return ESP_ERR_INVALID_ARG;
}
const esp_ds_data_t *data = esp_ds_ctx->data;
unsigned rsa_len = (data->rsa_length + 1) * 4;
while (ds_hal_busy()) { }
ds_signature_check_t sig_check_result = ds_hal_read_result((uint8_t*) signature, (size_t) rsa_len);
esp_err_t return_value = ESP_OK;
if (sig_check_result == DS_SIGNATURE_MD_FAIL || sig_check_result == DS_SIGNATURE_PADDING_AND_MD_FAIL) {
return_value = ESP32C3_ERR_HW_CRYPTO_DS_INVALID_DIGEST;
}
if (sig_check_result == DS_SIGNATURE_PADDING_FAIL) {
return_value = ESP32C3_ERR_HW_CRYPTO_DS_INVALID_PADDING;
}
free(esp_ds_ctx);
hmac_hal_clean();
ds_disable_release();
return return_value;
}
esp_err_t esp_ds_encrypt_params(esp_ds_data_t *data,
const void *iv,
const esp_ds_p_data_t *p_data,
const void *key)
{
if (!p_data) {
return ESP_ERR_INVALID_ARG;
}
esp_err_t result = ESP_OK;
esp_crypto_ds_lock_acquire();
periph_module_enable(PERIPH_AES_MODULE);
periph_module_enable(PERIPH_DS_MODULE);
periph_module_enable(PERIPH_SHA_MODULE);
periph_module_enable(PERIPH_HMAC_MODULE);
periph_module_enable(PERIPH_RSA_MODULE);
ets_ds_data_t *ds_data = (ets_ds_data_t*) data;
const ets_ds_p_data_t *ds_plain_data = (const ets_ds_p_data_t*) p_data;
ets_ds_result_t ets_result = ets_ds_encrypt_params(ds_data, iv, ds_plain_data, key, ETS_DS_KEY_HMAC);
if (ets_result == ETS_DS_INVALID_PARAM) {
result = ESP_ERR_INVALID_ARG;
}
periph_module_disable(PERIPH_RSA_MODULE);
periph_module_disable(PERIPH_HMAC_MODULE);
periph_module_disable(PERIPH_SHA_MODULE);
periph_module_disable(PERIPH_DS_MODULE);
periph_module_disable(PERIPH_AES_MODULE);
esp_crypto_ds_lock_release();
return result;
}