1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
|
.\" -*- mode: troff; coding: utf-8 -*-
.\" Automatically generated by Pod::Man 5.0102 (Pod::Simple 3.45)
.\"
.\" Standard preamble:
.\" ========================================================================
.de Sp \" Vertical space (when we can't use .PP)
.if t .sp .5v
.if n .sp
..
.de Vb \" Begin verbatim text
.ft CW
.nf
.ne \\$1
..
.de Ve \" End verbatim text
.ft R
.fi
..
.\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>.
.ie n \{\
. ds C` ""
. ds C' ""
'br\}
.el\{\
. ds C`
. ds C'
'br\}
.\"
.\" Escape single quotes in literal strings from groff's Unicode transform.
.ie \n(.g .ds Aq \(aq
.el .ds Aq '
.\"
.\" If the F register is >0, we'll generate index entries on stderr for
.\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index
.\" entries marked with X<> in POD. Of course, you'll have to process the
.\" output yourself in some meaningful fashion.
.\"
.\" Avoid warning from groff about undefined register 'F'.
.de IX
..
.nr rF 0
.if \n(.g .if rF .nr rF 1
.if (\n(rF:(\n(.g==0)) \{\
. if \nF \{\
. de IX
. tm Index:\\$1\t\\n%\t"\\$2"
..
. if !\nF==2 \{\
. nr % 0
. nr F 2
. \}
. \}
.\}
.rr rF
.\" ========================================================================
.\"
.IX Title "EVP_RAND-CTR-DRBG 7ossl"
.TH EVP_RAND-CTR-DRBG 7ossl 2025-07-01 3.5.1 OpenSSL
.\" For nroff, turn off justification. Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH NAME
EVP_RAND\-CTR\-DRBG \- The CTR DRBG EVP_RAND implementation
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Support for the counter deterministic random bit generator through the
\&\fBEVP_RAND\fR API.
.SS Identity
.IX Subsection "Identity"
"CTR-DRBG" is the name for this implementation; it can be used with the
\&\fBEVP_RAND_fetch()\fR function.
.SS "Supported parameters"
.IX Subsection "Supported parameters"
The supported parameters are:
.IP """state"" (\fBOSSL_RAND_PARAM_STATE\fR) <integer>" 4
.IX Item """state"" (OSSL_RAND_PARAM_STATE) <integer>"
.PD 0
.IP """strength"" (\fBOSSL_RAND_PARAM_STRENGTH\fR) <unsigned integer>" 4
.IX Item """strength"" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>"
.IP """max_request"" (\fBOSSL_RAND_PARAM_MAX_REQUEST\fR) <unsigned integer>" 4
.IX Item """max_request"" (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>"
.IP """reseed_requests"" (\fBOSSL_DRBG_PARAM_RESEED_REQUESTS\fR) <unsigned integer>" 4
.IX Item """reseed_requests"" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>"
.IP """reseed_time_interval"" (\fBOSSL_DRBG_PARAM_RESEED_TIME_INTERVAL\fR) <integer>" 4
.IX Item """reseed_time_interval"" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>"
.IP """min_entropylen"" (\fBOSSL_DRBG_PARAM_MIN_ENTROPYLEN\fR) <unsigned integer>" 4
.IX Item """min_entropylen"" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>"
.IP """max_entropylen"" (\fBOSSL_DRBG_PARAM_MAX_ENTROPYLEN\fR) <unsigned integer>" 4
.IX Item """max_entropylen"" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>"
.IP """min_noncelen"" (\fBOSSL_DRBG_PARAM_MIN_NONCELEN\fR) <unsigned integer>" 4
.IX Item """min_noncelen"" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>"
.IP """max_noncelen"" (\fBOSSL_DRBG_PARAM_MAX_NONCELEN\fR) <unsigned integer>" 4
.IX Item """max_noncelen"" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>"
.IP """max_perslen"" (\fBOSSL_DRBG_PARAM_MAX_PERSLEN\fR) <unsigned integer>" 4
.IX Item """max_perslen"" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>"
.IP """max_adinlen"" (\fBOSSL_DRBG_PARAM_MAX_ADINLEN\fR) <unsigned integer>" 4
.IX Item """max_adinlen"" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>"
.IP """reseed_counter"" (\fBOSSL_DRBG_PARAM_RESEED_COUNTER\fR) <unsigned integer>" 4
.IX Item """reseed_counter"" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>"
.IP """properties"" (\fBOSSL_DRBG_PARAM_PROPERTIES\fR) <UTF8 string>" 4
.IX Item """properties"" (OSSL_DRBG_PARAM_PROPERTIES) <UTF8 string>"
.IP """cipher"" (\fBOSSL_DRBG_PARAM_CIPHER\fR) <UTF8 string>" 4
.IX Item """cipher"" (OSSL_DRBG_PARAM_CIPHER) <UTF8 string>"
.PD
These parameters work as described in "PARAMETERS" in \fBEVP_RAND\fR\|(3).
.IP """use_derivation_function"" (\fBOSSL_DRBG_PARAM_USE_DF\fR) <integer>" 4
.IX Item """use_derivation_function"" (OSSL_DRBG_PARAM_USE_DF) <integer>"
This Boolean indicates if a derivation function should be used or not.
A nonzero value (the default) uses the derivation function. A zero value
does not.
.SH NOTES
.IX Header "NOTES"
A context for CTR DRBG can be obtained by calling:
.PP
.Vb 2
\& EVP_RAND *rand = EVP_RAND_fetch(NULL, "CTR\-DRBG", NULL);
\& EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL);
.Ve
.PP
The default CTR-DRBG implementation attempts to fetch the required internal
algorithms from the provider they are built into (eg the default provider)
regardless of the properties provided. Should the provider not implement
the required algorithms then properties will be used to find a different
implementation.
.SH EXAMPLES
.IX Header "EXAMPLES"
.Vb 5
\& EVP_RAND *rand;
\& EVP_RAND_CTX *rctx;
\& unsigned char bytes[100];
\& OSSL_PARAM params[2], *p = params;
\& unsigned int strength = 128;
\&
\& rand = EVP_RAND_fetch(NULL, "CTR\-DRBG", NULL);
\& rctx = EVP_RAND_CTX_new(rand, NULL);
\& EVP_RAND_free(rand);
\&
\& *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_CIPHER,
\& SN_aes_256_ctr, 0);
\& *p = OSSL_PARAM_construct_end();
\& EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
\&
\& EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
\&
\& EVP_RAND_CTX_free(rctx);
.Ve
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
NIST SP 800\-90A and SP 800\-90B
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBEVP_RAND\fR\|(3),
"PARAMETERS" in \fBEVP_RAND\fR\|(3)
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2020\-2025 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the Apache License 2.0 (the "License"). You may not use
this file except in compliance with the License. You can obtain a copy
in the file LICENSE in the source distribution or at
<https://www.openssl.org/source/license.html>.
|
