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.IX Title "EVP_RAND-CTR-DRBG 7SSL"
.TH EVP_RAND-CTR-DRBG 7SSL 2024-02-03 3.1.5 OpenSSL
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.nh
.SH NAME
EVP_RAND\-CTR\-DRBG \- The CTR DRBG EVP_RAND implementation
.SH DESCRIPTION
.IX Header "DESCRIPTION"
Support for the counter deterministic random bit generator through the
\&\fBEVP_RAND\fR API.
.SS Identity
.IX Subsection "Identity"
"CTR-DRBG" 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) <integer>" 4
.IX Item """state"" (OSSL_RAND_PARAM_STATE) <integer>"
.PD 0
.IP """strength"" (\fBOSSL_RAND_PARAM_STRENGTH\fR) <unsigned integer>" 4
.IX Item """strength"" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>"
.IP """max_request"" (\fBOSSL_RAND_PARAM_MAX_REQUEST\fR) <unsigned integer>" 4
.IX Item """max_request"" (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>"
.IP """reseed_requests"" (\fBOSSL_DRBG_PARAM_RESEED_REQUESTS\fR) <unsigned integer>" 4
.IX Item """reseed_requests"" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>"
.IP """reseed_time_interval"" (\fBOSSL_DRBG_PARAM_RESEED_TIME_INTERVAL\fR) <integer>" 4
.IX Item """reseed_time_interval"" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>"
.IP """min_entropylen"" (\fBOSSL_DRBG_PARAM_MIN_ENTROPYLEN\fR) <unsigned integer>" 4
.IX Item """min_entropylen"" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>"
.IP """max_entropylen"" (\fBOSSL_DRBG_PARAM_MAX_ENTROPYLEN\fR) <unsigned integer>" 4
.IX Item """max_entropylen"" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>"
.IP """min_noncelen"" (\fBOSSL_DRBG_PARAM_MIN_NONCELEN\fR) <unsigned integer>" 4
.IX Item """min_noncelen"" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>"
.IP """max_noncelen"" (\fBOSSL_DRBG_PARAM_MAX_NONCELEN\fR) <unsigned integer>" 4
.IX Item """max_noncelen"" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>"
.IP """max_perslen"" (\fBOSSL_DRBG_PARAM_MAX_PERSLEN\fR) <unsigned integer>" 4
.IX Item """max_perslen"" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>"
.IP """max_adinlen"" (\fBOSSL_DRBG_PARAM_MAX_ADINLEN\fR) <unsigned integer>" 4
.IX Item """max_adinlen"" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>"
.IP """reseed_counter"" (\fBOSSL_DRBG_PARAM_RESEED_COUNTER\fR) <unsigned integer>" 4
.IX Item """reseed_counter"" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>"
.IP """properties"" (\fBOSSL_DRBG_PARAM_PROPERTIES\fR) <UTF8 string>" 4
.IX Item """properties"" (OSSL_DRBG_PARAM_PROPERTIES) <UTF8 string>"
.IP """cipher"" (\fBOSSL_DRBG_PARAM_CIPHER\fR) <UTF8 string>" 4
.IX Item """cipher"" (OSSL_DRBG_PARAM_CIPHER) <UTF8 string>"
.PD
These parameters work as described in "PARAMETERS" in \fBEVP_RAND\fR\|(3).
.IP """use_derivation_function"" (\fBOSSL_DRBG_PARAM_USE_DF\fR) <integer>" 4
.IX Item """use_derivation_function"" (OSSL_DRBG_PARAM_USE_DF) <integer>"
This Boolean indicates if a derivation function should be used or not.
A nonzero value (the default) uses the derivation function.  A zero value
does not.
.SH NOTES
.IX Header "NOTES"
A context for CTR DRBG can be obtained by calling:
.PP
.Vb 2
\& EVP_RAND *rand = EVP_RAND_fetch(NULL, "CTR\-DRBG", NULL);
\& EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand);
.Ve
.SH EXAMPLES
.IX Header "EXAMPLES"
.Vb 5
\& EVP_RAND *rand;
\& EVP_RAND_CTX *rctx;
\& unsigned char bytes[100];
\& OSSL_PARAM params[2], *p = params;
\& unsigned int strength = 128;
\&
\& rand = EVP_RAND_fetch(NULL, "CTR\-DRBG", NULL);
\& rctx = EVP_RAND_CTX_new(rand, NULL);
\& EVP_RAND_free(rand);
\&
\& *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);
.Ve
.SH "CONFORMING TO"
.IX Header "CONFORMING TO"
NIST SP 800\-90A and SP 800\-90B
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fBEVP_RAND\fR\|(3),
"PARAMETERS" in \fBEVP_RAND\fR\|(3)
.SH COPYRIGHT
.IX Header "COPYRIGHT"
Copyright 2020\-2021 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
<https://www.openssl.org/source/license.html>.