5 life_cycle-rand - The RAND algorithm life-cycle
9 All random number generator (RANDs)
10 go through a number of stages in their life-cycle:
16 This state represents the RAND before it has been allocated. It is the
17 starting state for any life-cycle transitions.
21 This state represents the RAND after it has been allocated but unable to
26 This state represents the RAND when it is set up and capable of generating
31 This state represents the RAND when it has been shutdown and it is no longer
32 capable of generating output.
36 This state is entered when the RAND is freed. It is the terminal state
37 for all life-cycle transitions.
41 =head2 State Transition Diagram
43 The usual life-cycle of a RAND is illustrated:
47 +-------------------------+
49 +-------------------------+
53 +-------------------------+
55 +-------------------------+
57 | EVP_RAND_instantiate
59 EVP_RAND_generate +-------------------------+
60 +-------------------- | |
62 +-------------------> | | <+
63 +-------------------------+ '
65 | EVP_RAND_uninstantiate ' EVP_RAND_instantiate
67 +-------------------------+ '
69 +-------------------------+
73 +-------------------------+
75 +-------------------------+
79 =for html <img src="img/rand.png">
81 =head2 Formal State Transitions
83 This section defines all of the legal state transitions.
84 This is the canonical list.
88 Function Call ------------------ Current State ------------------
89 start newed instantiated uninstantiated freed
90 EVP_RAND_CTX_new newed
91 EVP_RAND_instantiate instantiated
92 EVP_RAND_generate instantiated
93 EVP_RAND_uninstantiate uninstantiated
94 EVP_RAND_CTX_free freed freed freed freed
95 EVP_RAND_CTX_get_params newed instantiated uninstantiated freed
96 EVP_RAND_CTX_set_params newed instantiated uninstantiated freed
97 EVP_RAND_CTX_gettable_params newed instantiated uninstantiated freed
98 EVP_RAND_CTX_settable_params newed instantiated uninstantiated freed
104 <table style="border:1px solid; border-collapse:collapse">
105 <tr><th style="border:1px solid" align="left">Function Call</th>
106 <th style="border:1px solid" colspan="5">Current State</th></tr>
107 <tr><th style="border:1px solid"></th>
108 <th style="border:1px solid" align="center">start</th>
109 <th style="border:1px solid" align="center">newed</th>
110 <th style="border:1px solid" align="center">instantiated</th>
111 <th style="border:1px solid" align="center">uninstantiated</th>
112 <th style="border:1px solid" align="center">freed</th></tr>
113 <tr><th style="border:1px solid" align="left">EVP_RAND_CTX_new</th>
114 <td style="border:1px solid" align="center">newed</td>
115 <td style="border:1px solid" align="center"></td>
116 <td style="border:1px solid" align="center"></td>
117 <td style="border:1px solid" align="center"></td>
118 <td style="border:1px solid" align="center"></td></tr>
119 <tr><th style="border:1px solid" align="left">EVP_RAND_instantiate</th>
120 <td style="border:1px solid" align="center"></td>
121 <td style="border:1px solid" align="center">instantiated</td>
122 <td style="border:1px solid" align="center"></td>
123 <td style="border:1px solid" align="center"></td>
124 <td style="border:1px solid" align="center"></td></tr>
125 <tr><th style="border:1px solid" align="left">EVP_RAND_generate</th>
126 <td style="border:1px solid" align="center"></td>
127 <td style="border:1px solid" align="center"></td>
128 <td style="border:1px solid" align="center">instantiated</td>
129 <td style="border:1px solid" align="center"></td>
130 <td style="border:1px solid" align="center"></td></tr>
131 <tr><th style="border:1px solid" align="left">EVP_RAND_uninstantiate</th>
132 <td style="border:1px solid" align="center"></td>
133 <td style="border:1px solid" align="center"></td>
134 <td style="border:1px solid" align="center">uninstantiated</td>
135 <td style="border:1px solid" align="center"></td>
136 <td style="border:1px solid" align="center"></td></tr>
137 <tr><th style="border:1px solid" align="left">EVP_RAND_CTX_free</th>
138 <td style="border:1px solid" align="center">freed</td>
139 <td style="border:1px solid" align="center">freed</td>
140 <td style="border:1px solid" align="center">freed</td>
141 <td style="border:1px solid" align="center">freed</td>
142 <td style="border:1px solid" align="center"></td></tr>
143 <tr><th style="border:1px solid" align="left">EVP_RAND_CTX_get_params</th>
144 <td style="border:1px solid" align="center"></td>
145 <td style="border:1px solid" align="center">newed</td>
146 <td style="border:1px solid" align="center">instantiated</td>
147 <td style="border:1px solid" align="center">uninstantiated</td>
148 <td style="border:1px solid" align="center"></td></tr>
149 <tr><th style="border:1px solid" align="left">EVP_RAND_CTX_set_params</th>
150 <td style="border:1px solid" align="center"></td>
151 <td style="border:1px solid" align="center">newed</td>
152 <td style="border:1px solid" align="center">instantiated</td>
153 <td style="border:1px solid" align="center">uninstantiated</td>
154 <td style="border:1px solid" align="center"></td></tr>
155 <tr><th style="border:1px solid" align="left">EVP_RAND_CTX_gettable_params</th>
156 <td style="border:1px solid" align="center"></td>
157 <td style="border:1px solid" align="center">newed</td>
158 <td style="border:1px solid" align="center">instantiated</td>
159 <td style="border:1px solid" align="center">uninstantiated</td>
160 <td style="border:1px solid" align="center"></td></tr>
161 <tr><th style="border:1px solid" align="left">EVP_RAND_CTX_settable_params</th>
162 <td style="border:1px solid" align="center"></td>
163 <td style="border:1px solid" align="center">newed</td>
164 <td style="border:1px solid" align="center">instantiated</td>
165 <td style="border:1px solid" align="center">uninstantiated</td>
166 <td style="border:1px solid" align="center"></td></tr>
173 At some point the EVP layer will begin enforcing the transitions described
178 L<provider-rand(7)>, L<EVP_RAND(3)>.
182 The provider RAND interface was introduced in OpenSSL 3.0.
186 Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
188 Licensed under the Apache License 2.0 (the "License"). You may not use
189 this file except in compliance with the License. You can obtain a copy
190 in the file LICENSE in the source distribution or at
191 L<https://www.openssl.org/source/license.html>.