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



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>.



3.0.12                            2023-05-07             EVP_RAND-TEST-RAND(7)