1 /*
2  * SPDX-FileCopyrightText: 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 #include <stdint.h>
11 
12 #ifdef __cplusplus
13 extern "C" {
14 #endif
15 
16 /**
17  * @brief  Get one random 32-bit word from hardware RNG
18  *
19  * If Wi-Fi or Bluetooth are enabled, this function returns true random numbers. In other
20  * situations, if true random numbers are required then consult the ESP-IDF Programming
21  * Guide "Random Number Generation" section for necessary prerequisites.
22  *
23  * This function automatically busy-waits to ensure enough external entropy has been
24  * introduced into the hardware RNG state, before returning a new random number. This delay
25  * is very short (always less than 100 CPU cycles).
26  *
27  * @return Random value between 0 and UINT32_MAX
28  */
29 uint32_t esp_random(void);
30 
31 /**
32  * @brief Fill a buffer with random bytes from hardware RNG
33  *
34  * @note This function is implemented via calls to esp_random(), so the same
35  * constraints apply.
36  *
37  * @param buf Pointer to buffer to fill with random numbers.
38  * @param len Length of buffer in bytes
39  */
40 void esp_fill_random(void *buf, size_t len);
41 
42 #ifdef __cplusplus
43 }
44 #endif
45