man > EVP_RAND-TEST-RAND(7)

EVP_RAND-TEST-RAND(7SSL)                       OpenSSL                      EVP_RAND-TEST-RAND(7SSL)

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.

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);

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 2020-2021 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>.

3.0.13                                       2026-07-29                     EVP_RAND-TEST-RAND(7SSL)