doc/man7/EVP_RAND-HMAC-DRBG.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 EVP_RAND-HMAC-DRBG - The HMAC DRBG EVP_RAND implementation
   6
   7 =head1 DESCRIPTION
   8
   9 Support for the HMAC deterministic random bit generator through the
  10 B<EVP_RAND> API.
  11
  12 =head2 Identity
  13
  14 "HMAC-DRBG" is the name for this implementation; it can be used with the
  15 EVP_RAND_fetch() function.
  16
  17 =head2 Supported parameters
  18
  19 The 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 "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
  28
  29 =item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
  30
  31 =item "max_request" (B<OSSL_DRBG_PARAM_MAX_REQUEST>) <unsigned 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
  53 These parameters work as described in L<EVP_RAND(3)/PARAMETERS>.
  54
  55 =back
  56
  57 =head1 NOTES
  58
  59 A 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_set_ctx_params(rctx, 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
  87 NIST SP 800-90A and SP 800-90B
  88
  89 =head1 SEE ALSO
  90
  91 L<EVP_RAND(3)>,
  92 L<EVP_RAND(3)/PARAMETERS>
  93
  94 =head1 COPYRIGHT
  95
  96 Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
  97
  98 Licensed under the Apache License 2.0 (the "License").  You may not use
  99 this file except in compliance with the License.  You can obtain a copy
 100 in the file LICENSE in the source distribution or at
 101 L<https://www.openssl.org/source/license.html>.
 102
 103 =cut