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      1 =pod
      2 
      3 =head1 NAME
      4 
      5 EVP_RAND-TEST-RAND - The test EVP_RAND implementation
      6 
      7 =head1 DESCRIPTION
      8 
      9 Support for a test generator through the B<EVP_RAND> API. This generator is
     10 for test purposes only, it does not generate random numbers.
     11 
     12 =head2 Identity
     13 
     14 "TEST-RAND" 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 "fips-indicator" (B<OSSL_RAND_PARAM_FIPS_APPROVED_INDICATOR>) <integer>
     26 
     27 These parameter works as described in L<EVP_RAND(3)/PARAMETERS>.
     28 
     29 =item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
     30 
     31 =item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
     32 
     33 =item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
     34 
     35 =item "max_request" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
     36 
     37 =item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
     38 
     39 =item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
     40 
     41 =item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
     42 
     43 =item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
     44 
     45 =item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
     46 
     47 =item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
     48 
     49 =item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
     50 
     51 These parameters work as described in L<EVP_RAND(3)/PARAMETERS>, except that
     52 they can all be set as well as read.
     53 
     54 =item "test_entropy" (B<OSSL_RAND_PARAM_TEST_ENTROPY>) <octet string>
     55 
     56 Sets the bytes returned when the test generator is sent an entropy request.
     57 The current position is remembered across generate calls.
     58 If there are insufficient data present to satisfy a call, an error is returned.
     59 
     60 =item "test_nonce" (B<OSSL_RAND_PARAM_TEST_NONCE>) <octet string>
     61 
     62 Sets the bytes returned when the test generator is sent a nonce request.
     63 Each nonce request will return all of the bytes.
     64 
     65 =item "generate" (B<OSSL_RAND_PARAM_GENERATE>) <integer>
     66 
     67 If this parameter is zero, it will only emit the nonce and entropy data
     68 supplied via the aforementioned parameters.  Otherwise, low quality
     69 non-cryptographic pseudorandom output is produced.  This parameter defaults
     70 to zero.
     71 
     72 =back
     73 
     74 =head1 NOTES
     75 
     76 A context for a test generator can be obtained by calling:
     77 
     78  EVP_RAND *rand = EVP_RAND_fetch(NULL, "TEST-RAND", NULL);
     79  EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL);
     80 
     81 =head1 EXAMPLES
     82 
     83  EVP_RAND *rand;
     84  EVP_RAND_CTX *rctx;
     85  unsigned char bytes[100];
     86  OSSL_PARAM params[4], *p = params;
     87  unsigned char entropy[1000] = { ... };
     88  unsigned char nonce[20] = { ... };
     89  unsigned int strength = 48;
     90 
     91  rand = EVP_RAND_fetch(NULL, "TEST-RAND", NULL);
     92  rctx = EVP_RAND_CTX_new(rand, NULL);
     93  EVP_RAND_free(rand);
     94 
     95  *p++ = OSSL_PARAM_construct_uint(OSSL_RAND_PARAM_STRENGTH, &strength);
     96  *p++ = OSSL_PARAM_construct_octet_string(OSSL_RAND_PARAM_TEST_ENTROPY,
     97                                           entropy, sizeof(entropy));
     98  *p++ = OSSL_PARAM_construct_octet_string(OSSL_RAND_PARAM_TEST_NONCE,
     99                                           nonce, sizeof(nonce));
    100  *p = OSSL_PARAM_construct_end();
    101  EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
    102 
    103  EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
    104 
    105  EVP_RAND_CTX_free(rctx);
    106 
    107 =head1 SEE ALSO
    108 
    109 L<EVP_RAND(3)>,
    110 L<EVP_RAND(3)/PARAMETERS>
    111 
    112 =head1 HISTORY
    113 
    114 This functionality was added in OpenSSL 3.0.
    115 
    116 =head1 COPYRIGHT
    117 
    118 Copyright 2020-2024 The OpenSSL Project Authors. All Rights Reserved.
    119 
    120 Licensed under the Apache License 2.0 (the "License").  You may not use
    121 this file except in compliance with the License.  You can obtain a copy
    122 in the file LICENSE in the source distribution or at
    123 L<https://www.openssl.org/source/license.html>.
    124 
    125 =cut
    126