NAME

       EVP_RAND-TEST-RAND - The test EVP_RAND implementation

DESCRIPTION

       Support for a test generator through the EVP_RAND API. This generator is for test purposes only, it does
       not generate random numbers.

   Identity
       "TEST-RAND" is the name for this implementation; it can be used with the EVP_RAND_fetch() function.

   Supported parameters
       The supported parameters are:

       "state" (OSSL_RAND_PARAM_STATE) <integer>
           These parameter works as described in "PARAMETERS" in EVP_RAND(3).

       "strength" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>
       "reseed_requests" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>
       "reseed_time_interval" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>
       "max_request" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>
       "min_entropylen" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>
       "max_entropylen" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>
       "min_noncelen" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>
       "max_noncelen" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>
       "max_perslen" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>
       "max_adinlen" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>
       "reseed_counter" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>
           These parameters work as described in "PARAMETERS" in EVP_RAND(3), except that they can all be set as
           well as read.

       "test_entropy" (OSSL_RAND_PARAM_TEST_ENTROPY) <octet string>
           Sets  the bytes returned when the test generator is sent an entropy request.  The current position is
           remembered across generate calls.  If there are insufficient data present to satisfy a call, an error
           is returned.

       "test_nonce" (OSSL_RAND_PARAM_TEST_NONCE) <octet string>
           Sets the bytes returned when the test generator is sent a nonce request.   Each  nonce  request  will
           return all of the bytes.

       "generate" (OSSL_RAND_PARAM_GENERATE) <integer>
           If  this  parameter  is  zero,  it  will  only  emit  the  nonce  and  entropy  data supplied via the
           aforementioned parameters.  Otherwise, low quality non-cryptographic pseudorandom output is produced.
           This parameter defaults to zero.

NOTES

       A context for a test generator can be obtained by calling:

        EVP_RAND *rand = EVP_RAND_fetch(NULL, "TEST-RAND", NULL);
        EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL);

EXAMPLES

        EVP_RAND *rand;
        EVP_RAND_CTX *rctx;
        unsigned char bytes[100];
        OSSL_PARAM params[4], *p = params;
        unsigned char entropy[1000] = { ... };
        unsigned char nonce[20] = { ... };
        unsigned int strength = 48;

        rand = EVP_RAND_fetch(NULL, "TEST-RAND", NULL);
        rctx = EVP_RAND_CTX_new(rand, NULL);
        EVP_RAND_free(rand);

        *p++ = OSSL_PARAM_construct_uint(OSSL_RAND_PARAM_STRENGTH, &strength);
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_RAND_PARAM_TEST_ENTROPY,
                                                 entropy, sizeof(entropy));
        *p++ = OSSL_PARAM_construct_octet_string(OSSL_RAND_PARAM_TEST_NONCE,
                                                 nonce, sizeof(nonce));
        *p = OSSL_PARAM_construct_end();
        EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);

        EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);

        EVP_RAND_CTX_free(rctx);

SEE ALSO

       EVP_RAND(3), "PARAMETERS" in EVP_RAND(3)

HISTORY

       This functionality was added in OpenSSL 3.0.

COPYRIGHT

       Copyright 2020-2023 The OpenSSL Project Authors. All Rights Reserved.

       Licensed under the Apache License 2.0 (the "License").  You may not use this file  except  in  compliance
       with  the  License.   You  can  obtain  a  copy  in  the  file  LICENSE  in the source distribution or at
       <https://www.openssl.org/source/license.html>.

3.3.1                                              2025-02-05                           EVP_RAND-TEST-RAND(7SSL)