1 /*
2  * SPDX-FileCopyrightText: 2021-2022 Espressif Systems (Shanghai) CO LTD
3  *
4  * SPDX-License-Identifier: Apache-2.0
5  */
6 
7 #ifndef __ESP_RANDOM_H__
8 #define __ESP_RANDOM_H__
9 
10 #include <stddef.h>
11 #include <stdint.h>
12 
13 #ifdef __cplusplus
14 extern "C" {
15 #endif
16 
17 /**
18  * @brief  Get one random 32-bit word from hardware RNG
19  *
20  * If Wi-Fi or Bluetooth are enabled, this function returns true random numbers. In other
21  * situations, if true random numbers are required then consult the ESP-IDF Programming
22  * Guide "Random Number Generation" section for necessary prerequisites.
23  *
24  * This function automatically busy-waits to ensure enough external entropy has been
25  * introduced into the hardware RNG state, before returning a new random number. This delay
26  * is very short (always less than 100 CPU cycles).
27  *
28  * @return Random value between 0 and UINT32_MAX
29  */
30 uint32_t esp_random(void);
31 
32 /**
33  * @brief Fill a buffer with random bytes from hardware RNG
34  *
35  * @note This function is implemented via calls to esp_random(), so the same
36  * constraints apply.
37  *
38  * @param buf Pointer to buffer to fill with random numbers.
39  * @param len Length of buffer in bytes
40  */
41 void esp_fill_random(void *buf, size_t len);
42 
43 #ifdef __cplusplus
44 }
45 #endif
46 
47 #endif /* __ESP_RANDOM_H__ */
48