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Title "EVP_RAND-SEED-SRC 7ossl"
EVP_RAND-SEED-SRC 7ossl "2023-09-19" "3.0.11" "OpenSSL"
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"NAME"
EVP_RAND-SEED-SRC - The randomness seed source EVP_RAND implementation
"DESCRIPTION"
Header "DESCRIPTION" Support for deterministic random number generator seeding through the \fB\s-1EVP_RAND\s0 \s-1API.\s0

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"
Subsection "Identity" \*(L"SEED-SRC\*(R" is the name for this implementation; it can be used with the \fBEVP_RAND_fetch() function.
"Supported parameters"
Subsection "Supported parameters" The supported parameters are: Item "state (OSSL_RAND_PARAM_STATE) <integer>"

0 Item "strength (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>" Item "max_request (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>"

These parameters work as described in \*(L"\s-1PARAMETERS\*(R"\s0 in \s-1EVP_RAND\s0\|(3).

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

.Vb 2 EVP_RAND *rand = EVP_RAND_fetch(NULL, "SEED-SRC", NULL); EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand); .Ve

"EXAMPLES"
Header "EXAMPLES" .Vb 5 EVP_RAND *rand; EVP_RAND_CTX *seed, *rctx; unsigned char bytes[100]; OSSL_PARAM params[2], *p = params; unsigned int strength = 128; \& /* Create a seed source */ rand = EVP_RAND_fetch(NULL, "SEED-SRC", NULL); seed = EVP_RAND_CTX_new(rand, 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); .Ve
"SEE ALSO"
Header "SEE ALSO" \s-1EVP_RAND\s0\|(3), \*(L"\s-1PARAMETERS\*(R"\s0 in \s-1EVP_RAND\s0\|(3)
"COPYRIGHT"
Header "COPYRIGHT" Copyright 2020-2021 The OpenSSL Project Authors. All Rights Reserved.

Licensed under the Apache License 2.0 (the \*(L"License\*(R"). You may not use this file except in compliance with the License. You can obtain a copy in the file \s-1LICENSE\s0 in the source distribution or at <https://www.openssl.org/source/license.html>.