1 /*
2  *  Copyright (c) 2019, The OpenThread Authors.
3  *  All rights reserved.
4  *
5  *  Redistribution and use in source and binary forms, with or without
6  *  modification, are permitted provided that the following conditions are met:
7  *  1. Redistributions of source code must retain the above copyright
8  *     notice, this list of conditions and the following disclaimer.
9  *  2. Redistributions in binary form must reproduce the above copyright
10  *     notice, this list of conditions and the following disclaimer in the
11  *     documentation and/or other materials provided with the distribution.
12  *  3. Neither the name of the copyright holder nor the
13  *     names of its contributors may be used to endorse or promote products
14  *     derived from this software without specific prior written permission.
15  *
16  *  THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
17  *  AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18  *  IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19  *  ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
20  *  LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
21  *  CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
22  *  SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
23  *  INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
24  *  CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
25  *  ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
26  *  POSSIBILITY OF SUCH DAMAGE.
27  */
28 
29 /**
30  * @file
31  * @brief
32  *  This file defines the OpenThread non cryptographic random number generator API.
33  */
34 
35 #ifndef OPENTHREAD_RANDOM_H_
36 #define OPENTHREAD_RANDOM_H_
37 
38 #include <stdint.h>
39 
40 #ifdef __cplusplus
41 extern "C" {
42 #endif
43 
44 /**
45  * @addtogroup api-random-non-crypto
46  *
47  * @brief
48  *   This module includes functions that generates non cryptographic random numbers.
49  *
50  * @{
51  *
52  */
53 
54 /**
55  * Generates and returns a random `uint32_t` value.
56  *
57  * @returns    A random `uint32_t` value.
58  *
59  */
60 uint32_t otRandomNonCryptoGetUint32(void);
61 
62 /**
63  * Generates and returns a random byte.
64  *
65  * @returns A random `uint8_t` value.
66  *
67  */
68 uint8_t otRandomNonCryptoGetUint8(void);
69 
70 /**
71  * Generates and returns a random `uint16_t` value.
72  *
73  * @returns A random `uint16_t` value.
74  *
75  */
76 uint16_t otRandomNonCryptoGetUint16(void);
77 
78 /**
79  * Generates and returns a random `uint8_t` value within a given range `[aMin, aMax)`.
80  *
81  * @param[in]  aMin  A minimum value (this value can be included in returned random result).
82  * @param[in]  aMax  A maximum value (this value is excluded from returned random result).
83  *
84  * @returns    A random `uint8_t` value in the given range (i.e., aMin <= random value < aMax).
85  */
86 uint8_t otRandomNonCryptoGetUint8InRange(uint8_t aMin, uint8_t aMax);
87 
88 /**
89  * Generates and returns a random `uint16_t` value within a given range `[aMin, aMax)`.
90  *
91  * @note The returned random value can include the @p aMin value but excludes the @p aMax.
92  *
93  * @param[in]  aMin  A minimum value (this value can be included in returned random result).
94  * @param[in]  aMax  A maximum value (this value is excluded from returned random result).
95  *
96  * @returns    A random `uint16_t` value in the given range (i.e., aMin <= random value < aMax).
97  */
98 uint16_t otRandomNonCryptoGetUint16InRange(uint16_t aMin, uint16_t aMax);
99 
100 /**
101  * Generates and returns a random `uint32_t` value within a given range `[aMin, aMax)`.
102  *
103  * @note The returned random value can include the @p aMin value but excludes the @p aMax.
104  *
105  * @param[in]  aMin  A minimum value (this value can be included in returned random result).
106  * @param[in]  aMax  A maximum value (this value is excluded from returned random result).
107  *
108  * @returns    A random `uint32_t` value in the given range (i.e., aMin <= random value < aMax).
109  *
110  */
111 uint32_t otRandomNonCryptoGetUint32InRange(uint32_t aMin, uint32_t aMax);
112 
113 /**
114  * Fills a given buffer with random bytes.
115  *
116  * @param[out] aBuffer  A pointer to a buffer to fill with the random bytes.
117  * @param[in]  aSize    Size of buffer (number of bytes to fill).
118  *
119  */
120 void otRandomNonCryptoFillBuffer(uint8_t *aBuffer, uint16_t aSize);
121 
122 /**
123  * Adds a random jitter within a given range to a given value.
124  *
125  * @param[in]  aValue     A value to which the random jitter is added.
126  * @param[in]  aJitter    Maximum jitter. Random jitter is selected from the range `[-aJitter, aJitter]`.
127  *
128  * @returns    The given value with an added random jitter.
129  *
130  */
131 uint32_t otRandomNonCryptoAddJitter(uint32_t aValue, uint16_t aJitter);
132 
133 /**
134  * @}
135  *
136  */
137 
138 #ifdef __cplusplus
139 } // extern "C"
140 #endif
141 
142 #endif // OPENTHREAD_RANDOM_H_
143