1 /**
2  * \file random.h
3  *
4  * \brief   This file contains the prototypes of helper functions to generate
5  *          random numbers for the purpose of testing.
6  */
7 
8 /*
9  *  Copyright The Mbed TLS Contributors
10  *  SPDX-License-Identifier: Apache-2.0
11  *
12  *  Licensed under the Apache License, Version 2.0 (the "License"); you may
13  *  not use this file except in compliance with the License.
14  *  You may obtain a copy of the License at
15  *
16  *  http://www.apache.org/licenses/LICENSE-2.0
17  *
18  *  Unless required by applicable law or agreed to in writing, software
19  *  distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
20  *  WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
21  *  See the License for the specific language governing permissions and
22  *  limitations under the License.
23  */
24 
25 #ifndef TEST_RANDOM_H
26 #define TEST_RANDOM_H
27 
28 #include "mbedtls/build_info.h"
29 
30 #include <stddef.h>
31 #include <stdint.h>
32 
33 typedef struct
34 {
35     unsigned char *buf; /* Pointer to a buffer of length bytes. */
36     size_t length;
37     /* If fallback_f_rng is NULL, fail after delivering length bytes. */
38     int ( *fallback_f_rng )( void*, unsigned char *, size_t );
39     void *fallback_p_rng;
40 } mbedtls_test_rnd_buf_info;
41 
42 /**
43  * Info structure for the pseudo random function
44  *
45  * Key should be set at the start to a test-unique value.
46  * Do not forget endianness!
47  * State( v0, v1 ) should be set to zero.
48  */
49 typedef struct
50 {
51     uint32_t key[16];
52     uint32_t v0, v1;
53 } mbedtls_test_rnd_pseudo_info;
54 
55 /**
56  * This function just returns data from rand().
57  * Although predictable and often similar on multiple
58  * runs, this does not result in identical random on
59  * each run. So do not use this if the results of a
60  * test depend on the random data that is generated.
61  *
62  * rng_state shall be NULL.
63  */
64 int mbedtls_test_rnd_std_rand( void *rng_state,
65                                unsigned char *output,
66                                size_t len );
67 
68 /**
69  * This function only returns zeros.
70  *
71  * \p rng_state shall be \c NULL.
72  */
73 int mbedtls_test_rnd_zero_rand( void *rng_state,
74                                 unsigned char *output,
75                                 size_t len );
76 
77 /**
78  * This function returns random data based on a buffer it receives.
79  *
80  * \p rng_state shall be a pointer to a #mbedtls_test_rnd_buf_info structure.
81  *
82  * The number of bytes released from the buffer on each call to
83  * the random function is specified by \p len.
84  *
85  * After the buffer is empty, this function will call the fallback RNG in the
86  * #mbedtls_test_rnd_buf_info structure if there is one, and
87  * will return #MBEDTLS_ERR_ENTROPY_SOURCE_FAILED otherwise.
88  */
89 int mbedtls_test_rnd_buffer_rand( void *rng_state,
90                                   unsigned char *output,
91                                   size_t len );
92 
93 /**
94  * This function returns random based on a pseudo random function.
95  * This means the results should be identical on all systems.
96  * Pseudo random is based on the XTEA encryption algorithm to
97  * generate pseudorandom.
98  *
99  * \p rng_state shall be a pointer to a #mbedtls_test_rnd_pseudo_info structure.
100  */
101 int mbedtls_test_rnd_pseudo_rand( void *rng_state,
102                                   unsigned char *output,
103                                   size_t len );
104 
105 #endif /* TEST_RANDOM_H */
106