1LIFE_CYCLE-RAND(7ossl)              OpenSSL             LIFE_CYCLE-RAND(7ossl)
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NAME

6       life_cycle-rand - The RAND algorithm life-cycle
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DESCRIPTION

9       All random number generator (RANDs) go through a number of stages in
10       their life-cycle:
11
12       start
13           This state represents the RAND before it has been allocated.  It is
14           the starting state for any life-cycle transitions.
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16       newed
17           This state represents the RAND after it has been allocated but
18           unable to generate any output.
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20       instantiated
21           This state represents the RAND when it is set up and capable of
22           generating output.
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24       uninstantiated
25           This state represents the RAND when it has been shutdown and it is
26           no longer capable of generating output.
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28       freed
29           This state is entered when the RAND is freed.  It is the terminal
30           state for all life-cycle transitions.
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32   State Transition Diagram
33       The usual life-cycle of a RAND is illustrated:
34                               +-------------------------+
35                               |          start          |
36                               +-------------------------+
37                                 |
38                                 | EVP_RAND_CTX_new
39                                 v
40                               +-------------------------+
41                               |          newed          |
42                               +-------------------------+
43                                 |
44                                 | EVP_RAND_instantiate
45                                 v
46           EVP_RAND_generate   +-------------------------+
47         +-------------------- |                         |
48         |                     |      instantiated       |
49         +-------------------> |                         | <+
50                               +-------------------------+  '
51                                 |                          '
52                                 | EVP_RAND_uninstantiate   '
53       EVP_RAND_instantiate
54                                 v                          '
55                               +-------------------------+  '
56                               |     uninstantiated      | -+
57                               +-------------------------+
58                                 |
59                                 | EVP_RAND_CTX_free
60                                 v
61                               +-------------------------+
62                               |          freed          |
63                               +-------------------------+
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65   Formal State Transitions
66       This section defines all of the legal state transitions.  This is the
67       canonical list.
68        Function Call              ------------------ Current State
69       ------------------
70                                   start   newed   instantiated
71       uninstantiated  freed
72        EVP_RAND_CTX_new           newed
73        EVP_RAND_instantiate            instantiated
74        EVP_RAND_generate                          instantiated
75        EVP_RAND_uninstantiate                    uninstantiated
76        EVP_RAND_CTX_free          freed   freed      freed          freed
77        EVP_RAND_CTX_get_params            newed   instantiated
78       uninstantiated  freed
79        EVP_RAND_CTX_set_params            newed   instantiated
80       uninstantiated  freed
81        EVP_RAND_CTX_gettable_params       newed   instantiated
82       uninstantiated  freed
83        EVP_RAND_CTX_settable_params       newed   instantiated
84       uninstantiated  freed
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NOTES

87       At some point the EVP layer will begin enforcing the transitions
88       described herein.
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SEE ALSO

91       provider-rand(7), EVP_RAND(3).
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HISTORY

94       The provider RAND interface was introduced in OpenSSL 3.0.
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97       Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
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99       Licensed under the Apache License 2.0 (the "License").  You may not use
100       this file except in compliance with the License.  You can obtain a copy
101       in the file LICENSE in the source distribution or at
102       <https://www.openssl.org/source/license.html>.
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1063.0.5                             2022-07-05            LIFE_CYCLE-RAND(7ossl)
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