1LIFE_CYCLE-DIGEST(7ossl) OpenSSL LIFE_CYCLE-DIGEST(7ossl)
2
6 life_cycle-digest - The digest algorithm life-cycle
7
9 All message digests (MDs) go through a number of stages in their life-
10 cycle:
11 start
13 This state represents the MD before it has been allocated. It is
14 the starting state for any life-cycle transitions.
15 newed
17 This state represents the MD after it has been allocated.
18 initialised
20 This state represents the MD when it is set up and capable of
21 processing input.
22 updated
24 This state represents the MD when it is set up and capable of
25 processing additional input or generating output.
26 finaled
28 This state represents the MD when it has generated output.
29 freed
31 This state is entered when the MD is freed. It is the terminal
32 state for all life-cycle transitions.
33 State Transition Diagram
35 The usual life-cycle of a MD is illustrated:
36 +-------------------+
37 | start |
38 +-------------------+
39 |
40 | EVP_MD_CTX_new
41 v
42 +-------------------+ EVP_MD_CTX_reset
43 | newed |
44 <------------------------------+
45 +-------------------+
46 |
47 |
48 |
49 | EVP_DigestInit
50 |
51 v
52 |
53 +-------------------+
54 |
55 +--> | initialised | <+ EVP_DigestInit
56 |
57 | +-------------------+ |
58 |
59 | | | EVP_DigestUpdate
60 |
61 | | EVP_DigestUpdate | +------------------+
62 |
63 | v | v |
64 |
65 | +------------------------------------------------+
66 |
67 EVP_DigestInit | | updated |
68 --+
69 | +------------------------------------------------+
70 |
71 | | |
72 |
73 | | EVP_DigestFinal | EVP_DigestFinalXOF
74 |
75 | v v
76 |
77 | +------------------------------------------------+
78 |
79 +--- | finaled |
80 --+
81 +------------------------------------------------+
82 |
83 | EVP_MD_CTX_free
84 v
85 +-------------------+
86 | freed |
87 +-------------------+
88 Formal State Transitions
90 This section defines all of the legal state transitions. This is the
91 canonical list.
92 Function Call --------------------- Current State
93 ----------------------
94 start newed initialised updated
95 finaled freed
96 EVP_MD_CTX_new newed
97 EVP_DigestInit initialised initialised initialised
98 initialised
99 EVP_DigestUpdate updated updated
100 EVP_DigestFinal finaled
101 EVP_DigestFinalXOF finaled
102 EVP_MD_CTX_free freed freed freed freed
103 freed
104 EVP_MD_CTX_reset newed newed newed
105 newed
106 EVP_MD_CTX_get_params newed initialised updated
107 EVP_MD_CTX_set_params newed initialised updated
108 EVP_MD_CTX_gettable_params newed initialised updated
109 EVP_MD_CTX_settable_params newed initialised updated
110
112 At some point the EVP layer will begin enforcing the transitions
113 described herein.
114
116 provider-digest(7), EVP_DigestInit(3)
117
119 Copyright 2021 The OpenSSL Project Authors. All Rights Reserved.
120 Licensed under the Apache License 2.0 (the "License"). You may not use
122 this file except in compliance with the License. You can obtain a copy
123 in the file LICENSE in the source distribution or at
124 <https://www.openssl.org/source/license.html>.
1253.0.5 2022-07-05 LIFE_CYCLE-DIGEST(7ossl)