components/bootloader_support/include/bootloader_random.h (ESP-IDF)

/* * SPDX-FileCopyrightText: 2010-2021 Espressif Systems (Shanghai) CO LTD * * SPDX-License-Identifier: Apache-2.0 */ #pragma once #include <stddef.h> #ifdef __cplusplus extern "C" { #endif /** * @brief Enable an entropy source for RNG if RF subsystem is disabled * * @warning This function is not safe to use if any other subsystem is accessing the RF subsystem or * the ADC at the same time! * * The exact internal entropy source mechanism depends on the chip in use but * all SoCs use the SAR ADC to continuously mix random bits (an internal * noise reading) into the HWRNG. Consult the SoC Technical Reference * Manual for more information. * * Can also be called from app code, if true random numbers are required without initialized RF subsystem. * This might be the case in early startup code of the application when the RF subsystem has not * started yet or if the RF subsystem should not be enabled for power saving. * * Consult ESP-IDF Programming Guide "Random Number Generation" section for * details. */ void bootloader_random_enable(void); /** * @brief Disable entropy source for RNG * * Disables internal entropy source. Must be called after * bootloader_random_enable() and before RF subsystem features, ADC, or * I2S (ESP32 only) are initialized. * * Consult the ESP-IDF Programming Guide "Random Number Generation" * section for details. */ void bootloader_random_disable(void); /** * @brief Fill buffer with 'length' random bytes * * @note If this function is being called from app code only, and never * from the bootloader, then it's better to call esp_fill_random(). * * @param buffer Pointer to buffer * @param length This many bytes of random data will be copied to buffer */ void bootloader_fill_random(void *buffer, size_t length); #ifdef __cplusplus } #endif