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66 lines
2.4 KiB
C
66 lines
2.4 KiB
C
// Copyright 2021 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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#pragma once
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#include <stddef.h>
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#include <stdint.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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* @brief Get one random 32-bit word from hardware RNG
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*
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* The hardware RNG produces true random numbers under any of the following conditions:
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*
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* - An RF subsystem is running (i.e. Bluetooth or WiFi is enabled)
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* - An internal entropy source has been enabled by calling bootloader_random_enable()
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* and not yet disabled by calling bootloader_random_disable()
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* - While the ESP-IDF bootloader is running (due to the internal entropy source being enabled
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* for the duration of bootloader execution).
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*
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* If none of the above conditions are true, the hardware RNG will produce pseudo-random numbers only.
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*
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* When the hardware RNG is producing true random numbers, external entropy (noise samples) are
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* continuously mixed into the internal hardware RNG state. Consult the SoC Technical Reference Manual
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* for more details.
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*
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* This function automatically busy-waits to ensure enough external entropy has been
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* introduced into the hardware RNG state, before returning a new random number.
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*
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* If generating random numbers from an app which has not yet enabled Bluetooth or Wi-Fi, call the
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* API function bootloader_random_enable() before generating random numbers and then call
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* bootloader_random_disable() before using any APIs for Bluetooth, Wi-Fi, ADC, or I2S. Consult the
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* bootloader_random.h header for more details.
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*
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* @return Random value between 0 and UINT32_MAX
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*/
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uint32_t esp_random(void);
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/**
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* @brief Fill a buffer with random bytes from hardware RNG
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*
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* @note This function has the same restrictions regarding available entropy as esp_random()
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*
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* @param buf Pointer to buffer to fill with random numbers.
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* @param len Length of buffer in bytes
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*/
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void esp_fill_random(void *buf, size_t len);
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#ifdef __cplusplus
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}
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#endif
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