.\" -*- mode: troff; coding: utf-8 -*- .\" Automatically generated by Pod::Man 5.0102 (Pod::Simple 3.45) .\" .\" Standard preamble: .\" ======================================================================== .de Sp \" Vertical space (when we can't use .PP) .if t .sp .5v .if n .sp .. .de Vb \" Begin verbatim text .ft CW .nf .ne \\$1 .. .de Ve \" End verbatim text .ft R .fi .. .\" \*(C` and \*(C' are quotes in nroff, nothing in troff, for use with C<>. .ie n \{\ . ds C` "" . ds C' "" 'br\} .el\{\ . ds C` . ds C' 'br\} .\" .\" Escape single quotes in literal strings from groff's Unicode transform. .ie \n(.g .ds Aq \(aq .el .ds Aq ' .\" .\" If the F register is >0, we'll generate index entries on stderr for .\" titles (.TH), headers (.SH), subsections (.SS), items (.Ip), and index .\" entries marked with X<> in POD. Of course, you'll have to process the .\" output yourself in some meaningful fashion. .\" .\" Avoid warning from groff about undefined register 'F'. .de IX .. .nr rF 0 .if \n(.g .if rF .nr rF 1 .if (\n(rF:(\n(.g==0)) \{\ . if \nF \{\ . de IX . tm Index:\\$1\t\\n%\t"\\$2" .. . if !\nF==2 \{\ . nr % 0 . nr F 2 . \} . \} .\} .rr rF .\" ======================================================================== .\" .IX Title "EVP_RAND-JITTER 7ssl" .TH EVP_RAND-JITTER 7ssl 2024-10-23 3.4.0 OpenSSL .\" For nroff, turn off justification. Always turn off hyphenation; it makes .\" way too many mistakes in technical documents. .if n .ad l .nh .SH NAME EVP_RAND\-JITTER \- The randomness seed source EVP_RAND implementation .SH DESCRIPTION .IX Header "DESCRIPTION" Support for deterministic random number generator seeding through the \&\fBEVP_RAND\fR API. .PP This software seed source produces randomness based on tiny CPU "jitter" fluctuations. .PP It is available when OpenSSL is compiled with \fBenable-jitter\fR option. When available it is listed in \fBopenssl list \&\-random\-generators\fR and \fBopenssl info \-seeds\fR. .SS Identity .IX Subsection "Identity" "JITTER" is the name for this implementation; it can be used with the \&\fBEVP_RAND_fetch()\fR function. .SS "Supported parameters" .IX Subsection "Supported parameters" The supported parameters are: .IP """state"" (\fBOSSL_RAND_PARAM_STATE\fR) " 4 .IX Item """state"" (OSSL_RAND_PARAM_STATE) " .PD 0 .IP """strength"" (\fBOSSL_RAND_PARAM_STRENGTH\fR) " 4 .IX Item """strength"" (OSSL_RAND_PARAM_STRENGTH) " .IP """max_request"" (\fBOSSL_RAND_PARAM_MAX_REQUEST\fR) " 4 .IX Item """max_request"" (OSSL_RAND_PARAM_MAX_REQUEST) " .PD These parameters work as described in "PARAMETERS" in \fBEVP_RAND\fR\|(3). .SH NOTES .IX Header "NOTES" A context for the seed source can be obtained by calling: .PP .Vb 2 \& EVP_RAND *rand = EVP_RAND_fetch(NULL, "JITTER", NULL); \& EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL); .Ve .PP The \fBenable-jitter\fR configuration option was added in OpenSSL 3.4. .SH EXAMPLES .IX 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 .SH "SEE ALSO" .IX Header "SEE ALSO" \&\fBEVP_RAND\fR\|(3), "PARAMETERS" in \fBEVP_RAND\fR\|(3) .SH COPYRIGHT .IX Header "COPYRIGHT" Copyright 2024 The OpenSSL Project Authors. All Rights Reserved. .PP 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 .