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1=pod
2
3=head1 NAME
4
5EVP_RAND-HMAC-DRBG - The HMAC DRBG EVP_RAND implementation
6
7=head1 DESCRIPTION
8
9Support for the HMAC deterministic random bit generator through the
10B<EVP_RAND> API.
11
12=head2 Identity
13
14"HMAC-DRBG" is the name for this implementation; it can be used with the
15EVP_RAND_fetch() function.
16
17=head2 Supported parameters
18
19The supported parameters are:
20
21=over 4
22
23=item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
24
25=item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
26
27=item "max_request" (B<OSSL_RAND_PARAM_MAX_REQUEST>) <unsigned integer>
28
29=item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
30
31=item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
32
33=item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
34
35=item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
36
37=item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
38
39=item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
40
41=item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
42
43=item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
44
45=item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
46
47=item "properties" (B<OSSL_DRBG_PARAM_PROPERTIES>) <UTF8 string>
48
49=item "mac" (B<OSSL_DRBG_PARAM_MAC>) <UTF8 string>
50
51=item "digest" (B<OSSL_DRBG_PARAM_DIGEST>) <UTF8 string>
52
53These parameters work as described in L<EVP_RAND(3)/PARAMETERS>.
54
55=back
56
57=head1 NOTES
58
59A context for HMAC DRBG can be obtained by calling:
60
61 EVP_RAND *rand = EVP_RAND_fetch(NULL, "HMAC-DRBG", NULL);
62 EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);
63
64=head1 EXAMPLES
65
66 EVP_RAND *rand;
67 EVP_RAND_CTX *rctx;
68 unsigned char bytes[100];
69 OSSL_PARAM params[3], *p = params;
70 unsigned int strength = 128;
71
72 rand = EVP_RAND_fetch(NULL, "HMAC-DRBG", NULL);
73 rctx = EVP_RAND_CTX_new(rand, NULL);
74 EVP_RAND_free(rand);
75
76 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_MAC, SN_hmac, 0);
77 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_DIGEST, SN_sha256, 0);
78 *p = OSSL_PARAM_construct_end();
79 EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
80
81 EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
82
83 EVP_RAND_CTX_free(rctx);
84
85=head1 CONFORMING TO
86
87NIST SP 800-90A and SP 800-90B
88
89=head1 SEE ALSO
90
91L<EVP_RAND(3)>,
92L<EVP_RAND(3)/PARAMETERS>
93
94=head1 COPYRIGHT
95
96Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
97
98Licensed under the Apache License 2.0 (the "License").  You may not use
99this file except in compliance with the License.  You can obtain a copy
100in the file LICENSE in the source distribution or at
101L<https://www.openssl.org/source/license.html>.
102
103=cut
104