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Title "EVP_RAND-JITTER 7ossl" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
EVP_RAND-JITTER - The randomness seed source EVP_RAND implementation Header "DESCRIPTION" Support for deterministic random number generator seeding through the \fBEVP_RAND API.

This software seed source produces randomness based on tiny CPU "jitter" fluctuations.

It is available when OpenSSL is compiled with enable-jitter option. When available it is listed in openssl list \-random-generators and openssl info -seeds.

Subsection "Identity" "JITTER" is the name for this implementation; it can be used with the \fBEVP_RAND_fetch() function. 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 "PARAMETERS" in EVP_RAND\|(3).

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

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

The enable-jitter option was added in OpenSSL 3.4.

By specifying the enable-fips-jitter configuration option, the FIPS provider will use an internal jitter source for its entropy. Enabling this option will cause the FIPS provider to operate in a non-compliant mode unless an entropy assessment ESV <https://csrc.nist.gov/Projects/cryptographic-module-validation-program/entropy-validations> and validation through the CMVP <https://csrc.nist.gov/projects/cryptographic-module-validation-program> are additionally conducted. This option was added in OpenSSL 3.5.

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 and instantiate a seed source */ rand = EVP_RAND_fetch(NULL, "JITTER", 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); .Ve Header "SEE ALSO" \fBEVP_RAND\|(3), "PARAMETERS" in EVP_RAND\|(3) Header "COPYRIGHT" Copyright 2024 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>.