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c215bb04f6
If JTAG is disabled temporarily by burning SOFT_DIS_JTAG, it can be re-enabled temporarily through esp_hmac_jtag_enable API
97 lines
3.5 KiB
C
97 lines
3.5 KiB
C
// Copyright 2015-2020 Espressif Systems (Shanghai) PTE LTD
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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#ifndef _ESP_HMAC_H_
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#define _ESP_HMAC_H_
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#include <stdbool.h>
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#include "esp_err.h"
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#ifdef __cplusplus
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extern "C" {
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#endif
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/**
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* The possible efuse keys for the HMAC peripheral
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*/
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typedef enum {
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HMAC_KEY0 = 0,
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HMAC_KEY1,
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HMAC_KEY2,
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HMAC_KEY3,
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HMAC_KEY4,
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HMAC_KEY5,
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HMAC_KEY_MAX
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} hmac_key_id_t;
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/**
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* @brief
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* Calculate the HMAC of a given message.
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*
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* Calculate the HMAC \c hmac of a given message \c message with length \c message_len.
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* SHA256 is used for the calculation (fixed on ESP32S2).
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*
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* @note Uses the HMAC peripheral in "upstream" mode.
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*
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* @param key_id Determines which of the 6 key blocks in the efuses should be used for the HMAC calcuation.
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* The corresponding purpose field of the key block in the efuse must be set to the HMAC upstream purpose value.
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* @param message the message for which to calculate the HMAC
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* @param message_len message length
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* return ESP_ERR_INVALID_STATE if unsuccessful
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* @param [out] hmac the hmac result; the buffer behind the provided pointer must be 32 bytes long
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*
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* @return
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* * ESP_OK, if the calculation was successful,
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* * ESP_FAIL, if the hmac calculation failed
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*/
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esp_err_t esp_hmac_calculate(hmac_key_id_t key_id,
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const void *message,
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size_t message_len,
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uint8_t *hmac);
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/**
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* @brief Use HMAC peripheral in Downstream mode to re-enable the JTAG, if it is not permanently disabled by HW.
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* In downstream mode, HMAC calculations performed by peripheral are used internally and not provided back to user.
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*
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* @param key_id Determines which of the 6 key blocks in the efuses should be used for the HMAC calculation.
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* The corresponding purpose field of the key block in the efuse must be set to HMAC downstream purpose.
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*
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* @param token Pre calculated HMAC value of the 32-byte 0x00 using SHA-256 and the known private HMAC key. The key is already
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* programmed to a eFuse key block. The key block number is provided as the first parameter to this function.
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*
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* @return
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* * ESP_OK, if the calculation was successful,
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* if the calculated HMAC value matches with provided token,
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* JTAG will be re-enable otherwise JTAG will remain disabled.
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* Return value does not indicate the JTAG status.
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* * ESP_FAIL, if the hmac calculation failed or JTAG is permanently disabled by EFUSE_HARD_DIS_JTAG eFuse parameter.
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* * ESP_ERR_INVALID_ARG, invalid input arguments
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*/
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esp_err_t esp_hmac_jtag_enable(hmac_key_id_t key_id, const uint8_t *token);
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/**
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* @brief Disable the JTAG which might be enabled using the HMAC downstream mode. This function just clears the result generated
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* by calling esp_hmac_jtag_enable() API.
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*
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* @return
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* * ESP_OK return ESP_OK after writing the HMAC_SET_INVALIDATE_JTAG_REG with value 1.
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*/
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esp_err_t esp_hmac_jtag_disable(void);
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#ifdef __cplusplus
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}
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#endif
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#endif // _ESP_HMAC_H_
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