1=pod
2
3=head1 NAME
4
5EVP_RAND-HASH-DRBG - The HASH DRBG EVP_RAND implementation
6
7=head1 DESCRIPTION
8
9Support for the hash deterministic random bit generator through the
10B<EVP_RAND> API.
11
12=head2 Identity
13
14"HASH-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 "digest" (B<OSSL_DRBG_PARAM_DIGEST>) <UTF8 string>
50
51These parameters work as described in L<EVP_RAND(3)/PARAMETERS>.
52
53=back
54
55=head1 NOTES
56
57A context for HASH DRBG can be obtained by calling:
58
59 EVP_RAND *rand = EVP_RAND_fetch(NULL, "HASH-DRBG", NULL);
60 EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);
61
62=head1 EXAMPLES
63
64 EVP_RAND *rand;
65 EVP_RAND_CTX *rctx;
66 unsigned char bytes[100];
67 OSSL_PARAM params[2], *p = params;
68 unsigned int strength = 128;
69
70 rand = EVP_RAND_fetch(NULL, "HASH-DRBG", NULL);
71 rctx = EVP_RAND_CTX_new(rand, NULL);
72 EVP_RAND_free(rand);
73
74 *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_DIGEST, SN_sha512, 0);
75 *p = OSSL_PARAM_construct_end();
76 EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
77
78 EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
79
80 EVP_RAND_CTX_free(rctx);
81
82=head1 CONFORMING TO
83
84NIST SP 800-90A and SP 800-90B
85
86=head1 SEE ALSO
87
88L<EVP_RAND(3)>,
89L<EVP_RAND(3)/PARAMETERS>
90
91=head1 COPYRIGHT
92
93Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.
94
95Licensed under the Apache License 2.0 (the "License").  You may not use
96this file except in compliance with the License.  You can obtain a copy
97in the file LICENSE in the source distribution or at
98L<https://www.openssl.org/source/license.html>.
99
100=cut
101