esp-idf/components/esp32s2/include/esp_hmac.h
2020-09-28 23:40:59 +05:30

100 lines
3.5 KiB
C

// Copyright 2015-2020 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.
#ifndef _ESP_HMAC_H_
#define _ESP_HMAC_H_
#include "esp_err.h"
#include "stdbool.h"
#ifdef __cplusplus
extern "C" {
#endif
/**
* The possible efuse keys for the HMAC peripheral
*/
typedef enum {
HMAC_KEY0 = 0,
HMAC_KEY1,
HMAC_KEY2,
HMAC_KEY3,
HMAC_KEY4,
HMAC_KEY5,
HMAC_KEY_MAX
} hmac_key_id_t;
/**
* @brief
* Calculate the HMAC of a given message.
*
* Calculate the HMAC \c hmac of a given message \c message with length \c message_len.
* SHA256 is used for the calculation (fixed on ESP32S2).
*
* @note Uses the HMAC peripheral in "upstream" mode.
*
* @param key_id Determines which of the 6 key blocks in the efuses should be used for the HMAC calcuation.
* The corresponding purpose field of the key block in the efuse must be set to the HMAC upstream purpose value.
* @param message the message for which to calculate the HMAC
* @param message_len message length
* return ESP_ERR_INVALID_STATE if unsuccessful
* @param [out] hmac the hmac result; the buffer behind the provided pointer must be 32 bytes long
*
* @return
* * ESP_OK, if the calculation was successful,
* * ESP_FAIL, if the hmac calculation failed
*/
esp_err_t esp_hmac_calculate(hmac_key_id_t key_id,
const void *message,
size_t message_len,
uint8_t *hmac);
/**
* @brief
* Use HMAC peripheral in Downstream mode to re-enable the JTAG, if it is not permanently disable by HW.
* In downstream mode HMAC calculations perfomred by peripheral used internally and not provided back to user.
*
* @param key_id Determines which of the 6 key blocks in the efuses should be used for the HMAC calculation.
* The corresponding purpose field of the key block in the efuse must be set to HMAC downstream purpose.
*
* @param token Pre calculated HMAC value of the 32-byte 0x00 using SHA-256 and the known private HMAC key. The key is already
* programmed to a eFuse key block. The key block number is provided as the first parameter to this function.
*
* @return
* * ESP_OK, if the calculation was successful,
* if the calculated HMAC value matches with provided token,
* JTAG will be re-enable otherwise JTAG will remain disabled.
* Return value does not indicate the JTAG status.
* * ESP_FAIL, if the hmac calculation failed or JTAG is permanently disabled by EFUSE_HARD_DIS_JTAG eFuse parameter.
* * ESP_ERR_INVALID_ARG, invalid input arguments
*/
esp_err_t esp_hmac_jtag_enable(hmac_key_id_t key_id,
const uint8_t *token);
/**
* @brief
* Disable the JTAG which might be enable using the HMAC downstream mode. This function just clear the result generated by
* JTAG key by calling esp_hmac_jtag_enable() API.
*
* @return
* * ESP_OK return ESP_OK after writing the HMAC_SET_INVALIDATE_JTAG_REG with value 1.
*/
esp_err_t esp_hmac_jtag_disable(void);
#ifdef __cplusplus
}
#endif
#endif // _ESP_HMAC_H_