NAME

EVP_RAND-CTR-DRBG - The CTR DRBG EVP_RAND implementation

DESCRIPTION

Support for the counter deterministic random bit generator through the EVP_RAND API.

Identity

"CTR-DRBG" is the name for this implementation; it can be used with the EVP_RAND_fetch() function.

Supported parameters

The supported parameters are:

"state" (OSSL_RAND_PARAM_STATE) <integer>
"strength" (OSSL_RAND_PARAM_STRENGTH) <unsigned integer>
"max_request" (OSSL_RAND_PARAM_MAX_REQUEST) <unsigned integer>
"reseed_requests" (OSSL_DRBG_PARAM_RESEED_REQUESTS) <unsigned integer>
"reseed_time_interval" (OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL) <integer>
"min_entropylen" (OSSL_DRBG_PARAM_MIN_ENTROPYLEN) <unsigned integer>
"max_entropylen" (OSSL_DRBG_PARAM_MAX_ENTROPYLEN) <unsigned integer>
"min_noncelen" (OSSL_DRBG_PARAM_MIN_NONCELEN) <unsigned integer>
"max_noncelen" (OSSL_DRBG_PARAM_MAX_NONCELEN) <unsigned integer>
"max_perslen" (OSSL_DRBG_PARAM_MAX_PERSLEN) <unsigned integer>
"max_adinlen" (OSSL_DRBG_PARAM_MAX_ADINLEN) <unsigned integer>
"reseed_counter" (OSSL_DRBG_PARAM_RESEED_COUNTER) <unsigned integer>
"properties" (OSSL_DRBG_PARAM_PROPERTIES) <UTF8 string>
"cipher" (OSSL_DRBG_PARAM_CIPHER) <UTF8 string>: These parameters work as described in "PARAMETERS" in EVP_RAND(3).
"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.

NOTES

A context for CTR DRBG can be obtained by calling:

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

EXAMPLES

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);

CONFORMING TO

NIST SP 800-90A and SP 800-90B

COPYRIGHT

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.