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55 lines
1.9 KiB
C
55 lines
1.9 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 is fully functional whenever an RF subsystem is running (ie Bluetooth or WiFi is enabled). For
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* random values, call this function after WiFi or Bluetooth are started.
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*
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* If the RF subsystem is not used by the program, the function bootloader_random_enable() can be called to enable an
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* entropy source. bootloader_random_disable() must be called before RF subsystem or I2S peripheral are used. See these functions'
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* documentation for more details.
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*
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* Any time the app is running without an RF subsystem (or bootloader_random) enabled, RNG hardware should be
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* considered a PRNG. A very small amount of entropy is available due to pre-seeding while the IDF
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* bootloader is running, but this should not be relied upon for any use.
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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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