$NetBSD: EVP_RAND-CTR-DRBG.7,v 1.5 2024/09/08 13:08:24 christos Exp $

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Title "EVP_RAND-CTR-DRBG 7" For nroff, turn off justification. Always turn off hyphenation; it makes
way too many mistakes in technical documents.
EVP_RAND-CTR-DRBG - The CTR DRBG EVP_RAND implementation Header "DESCRIPTION" Support for the counter deterministic random bit generator through the \fBEVP_RAND API. Subsection "Identity" "CTR-DRBG" 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>"

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Item """strength"" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>" Item """max_request"" (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>" Item """reseed_requests"" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>" Item """reseed_time_interval"" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>" Item """min_entropylen"" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>" Item """max_entropylen"" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>" Item """min_noncelen"" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>" Item """max_noncelen"" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>" Item """max_perslen"" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>" Item """max_adinlen"" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>" Item """reseed_counter"" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>" Item """properties"" (OSSL_DRBG_PARAM_PROPERTIES) <UTF8 string>" Item """cipher"" (OSSL_DRBG_PARAM_CIPHER) <UTF8 string>"

These parameters work as described in "PARAMETERS" in EVP_RAND\|(3).

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. Header "NOTES" A context for CTR DRBG can be obtained by calling:

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

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 Header "CONFORMING TO" NIST SP 800-90A and SP 800-90B Header "SEE ALSO" \fBEVP_RAND\|(3), "PARAMETERS" in EVP_RAND\|(3) Header "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>.