EVP_RAND-SEED-SRC(7) - NetBSD Manual Pages

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EVP_RAND-SEED-SRC(7)                OpenSSL               EVP_RAND-SEED-SRC(7)




NAME

       EVP_RAND-SEED-SRC - The randomness seed source EVP_RAND implementation


DESCRIPTION

       Support for deterministic random number generator seeding through the
       EVP_RAND API.

       The seed sources used are specified at the time OpenSSL is configured
       for building using the --with-rand-seed= option.  By default, operating
       system randomness sources are used.

   Identity
       "SEED-SRC" 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>
       "strength" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>
       "max_request" (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>
           These parameters work as described in "PARAMETERS" in EVP_RAND(3).


NOTES

       A context for the seed source can be obtained by calling:

        EVP_RAND *rand = EVP_RAND_fetch(NULL, "SEED-SRC", NULL);
        EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);


EXAMPLES

        EVP_RAND *rand;
        EVP_RAND_CTX *seed, *rctx;
        unsigned char bytes[100];
        OSSL_PARAM params[2], *p = params;
        unsigned int strength = 128;

        /* Create and instantiate a seed source */
        rand = EVP_RAND_fetch(NULL, "SEED-SRC", NULL);
        seed = EVP_RAND_CTX_new(rand, NULL);
        EVP_RAND_instantiate(seed, strength, 0, NULL, 0, NULL);
        EVP_RAND_free(rand);

        /* Feed this into a DRBG */
        rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
        rctx = EVP_RAND_CTX_new(rand, seed);
        EVP_RAND_free(rand);

        /* Configure the DRBG */
        *p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_CIPHER,
                                                SN_aes_256_ctr, 0);
        *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);
        EVP_RAND_CTX_free(seed);


SEE ALSO

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


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>.



3.0.15                            2024-09-03              EVP_RAND-SEED-SRC(7)