1 /* 2 * SPDX-FileCopyrightText: 2010-2021 Espressif Systems (Shanghai) CO LTD 3 * 4 * SPDX-License-Identifier: Apache-2.0 5 */ 6 7 #pragma once 8 9 #include <stddef.h> 10 11 #ifdef __cplusplus 12 extern "C" { 13 #endif 14 15 /** 16 * @brief Enable an entropy source for RNG if RF subsystem is disabled 17 * 18 * @warning This function is not safe to use if any other subsystem is accessing the RF subsystem or 19 * the ADC at the same time! 20 * 21 * The exact internal entropy source mechanism depends on the chip in use but 22 * all SoCs use the SAR ADC to continuously mix random bits (an internal 23 * noise reading) into the HWRNG. Consult the SoC Technical Reference 24 * Manual for more information. 25 * 26 * Can also be called from app code, if true random numbers are required without initialized RF subsystem. 27 * This might be the case in early startup code of the application when the RF subsystem has not 28 * started yet or if the RF subsystem should not be enabled for power saving. 29 * 30 * Consult ESP-IDF Programming Guide "Random Number Generation" section for 31 * details. 32 */ 33 void bootloader_random_enable(void); 34 35 /** 36 * @brief Disable entropy source for RNG 37 * 38 * Disables internal entropy source. Must be called after 39 * bootloader_random_enable() and before RF subsystem features, ADC, or 40 * I2S (ESP32 only) are initialized. 41 * 42 * Consult the ESP-IDF Programming Guide "Random Number Generation" 43 * section for details. 44 */ 45 void bootloader_random_disable(void); 46 47 /** 48 * @brief Fill buffer with 'length' random bytes 49 * 50 * @note If this function is being called from app code only, and never 51 * from the bootloader, then it's better to call esp_fill_random(). 52 * 53 * @param buffer Pointer to buffer 54 * @param length This many bytes of random data will be copied to buffer 55 */ 56 void bootloader_fill_random(void *buffer, size_t length); 57 58 #ifdef __cplusplus 59 } 60 #endif 61
