doc/man7/EVP_RAND-CTR-DRBG.pod

   1 =pod
   2
   3 =head1 NAME
   4
   5 EVP_RAND-CTR-DRBG - The CTR DRBG EVP_RAND implementation
   6
   7 =head1 DESCRIPTION
   8
   9 Support for the counter deterministic random bit generator through the
  10 B<EVP_RAND> API.
  11
  12 =head2 Identity
  13
  14 "CTR-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 "cipher" (B<OSSL_DRBG_PARAM_CIPHER>) <UTF8 string>
  50
  51 These parameters work as described in L<EVP_RAND(3)/PARAMETERS>.
  52
  53 =item "use_derivation_function" (B<OSSL_DRBG_PARAM_USE_DF>) <int>
  54
  55 This Boolean indicates if a derivation function should be used or not.
  56 A nonzero value (the default) uses the derivation function.  A zero value
  57 does not.  The FIPS provider always uses the derivation function and attempts
  58 to set this value result in an error.
  59
  60 =back
  61
  62 =head1 NOTES
  63
  64 A context for CTR DRBG can be obtained by calling:
  65
  66  EVP_RAND *rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
  67  EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);
  68
  69 =head1 EXAMPLES
  70
  71  EVP_RAND *rand;
  72  EVP_RAND_CTX *rctx;
  73  unsigned char bytes[100];
  74  OSSL_PARAM params[2], *p = params;
  75  unsigned int strength = 128;
  76
  77  rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
  78  rctx = EVP_RAND_CTX_new(rand, NULL);
  79  EVP_RAND_free(rand);
  80
  81  *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_CIPHER,
  82                                          SN_aes_256_ctr, 0);
  83  *p = OSSL_PARAM_construct_end();
  84  EVP_RAND_set_ctx_params(rctx, params);
  85
  86  EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
  87
  88  EVP_RAND_CTX_free(rctx);
  89
  90 =head1 CONFORMING TO
  91
  92 NIST SP 800-90A and SP 800-90B
  93
  94 =head1 SEE ALSO
  95
  96 L<EVP_RAND(3)>,
  97 L<EVP_RAND(3)/PARAMETERS>
  98
  99 =head1 COPYRIGHT
 100
 101 Copyright 2020 The OpenSSL Project Authors. All Rights Reserved.
 102
 103 Licensed under the Apache License 2.0 (the "License").  You may not use
 104 this file except in compliance with the License.  You can obtain a copy
 105 in the file LICENSE in the source distribution or at
 106 L<https://www.openssl.org/source/license.html>.
 107
 108 =cut