0c679f5566
Reviewed-by: Neil Horman <nhorman@openssl.org> Reviewed-by: Matt Caswell <matt@openssl.org> Release: yes
113 lines
3.1 KiB
Text
113 lines
3.1 KiB
Text
=pod
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=head1 NAME
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EVP_RAND-CTR-DRBG - The CTR DRBG EVP_RAND implementation
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=head1 DESCRIPTION
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Support for the counter deterministic random bit generator through the
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B<EVP_RAND> API.
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=head2 Identity
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"CTR-DRBG" is the name for this implementation; it can be used with the
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EVP_RAND_fetch() function.
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=head2 Supported parameters
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The supported parameters are:
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=over 4
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=item "state" (B<OSSL_RAND_PARAM_STATE>) <integer>
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=item "strength" (B<OSSL_RAND_PARAM_STRENGTH>) <unsigned integer>
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=item "max_request" (B<OSSL_RAND_PARAM_MAX_REQUEST>) <unsigned integer>
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=item "reseed_requests" (B<OSSL_DRBG_PARAM_RESEED_REQUESTS>) <unsigned integer>
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=item "reseed_time_interval" (B<OSSL_DRBG_PARAM_RESEED_TIME_INTERVAL>) <integer>
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=item "min_entropylen" (B<OSSL_DRBG_PARAM_MIN_ENTROPYLEN>) <unsigned integer>
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=item "max_entropylen" (B<OSSL_DRBG_PARAM_MAX_ENTROPYLEN>) <unsigned integer>
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=item "min_noncelen" (B<OSSL_DRBG_PARAM_MIN_NONCELEN>) <unsigned integer>
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=item "max_noncelen" (B<OSSL_DRBG_PARAM_MAX_NONCELEN>) <unsigned integer>
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=item "max_perslen" (B<OSSL_DRBG_PARAM_MAX_PERSLEN>) <unsigned integer>
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=item "max_adinlen" (B<OSSL_DRBG_PARAM_MAX_ADINLEN>) <unsigned integer>
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=item "reseed_counter" (B<OSSL_DRBG_PARAM_RESEED_COUNTER>) <unsigned integer>
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=item "properties" (B<OSSL_DRBG_PARAM_PROPERTIES>) <UTF8 string>
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=item "cipher" (B<OSSL_DRBG_PARAM_CIPHER>) <UTF8 string>
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These parameters work as described in L<EVP_RAND(3)/PARAMETERS>.
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=item "use_derivation_function" (B<OSSL_DRBG_PARAM_USE_DF>) <integer>
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This Boolean indicates if a derivation function should be used or not.
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A nonzero value (the default) uses the derivation function. A zero value
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does not.
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=back
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=head1 NOTES
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A context for CTR DRBG can be obtained by calling:
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EVP_RAND *rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
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EVP_RAND_CTX *rctx = EVP_RAND_CTX_new(rand, NULL);
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The default CTR-DRBG implementation attempts to fetch the required internal
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algorithms from the provider they are built into (eg the default provider)
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regardless of the properties provided. Should the provider not implement
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the required algorithms then properties will be used to find a different
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implementation.
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=head1 EXAMPLES
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EVP_RAND *rand;
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EVP_RAND_CTX *rctx;
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unsigned char bytes[100];
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OSSL_PARAM params[2], *p = params;
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unsigned int strength = 128;
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rand = EVP_RAND_fetch(NULL, "CTR-DRBG", NULL);
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rctx = EVP_RAND_CTX_new(rand, NULL);
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EVP_RAND_free(rand);
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*p++ = OSSL_PARAM_construct_utf8_string(OSSL_DRBG_PARAM_CIPHER,
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SN_aes_256_ctr, 0);
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*p = OSSL_PARAM_construct_end();
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EVP_RAND_instantiate(rctx, strength, 0, NULL, 0, params);
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EVP_RAND_generate(rctx, bytes, sizeof(bytes), strength, 0, NULL, 0);
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EVP_RAND_CTX_free(rctx);
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=head1 CONFORMING TO
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NIST SP 800-90A and SP 800-90B
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=head1 SEE ALSO
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L<EVP_RAND(3)>,
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L<EVP_RAND(3)/PARAMETERS>
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=head1 COPYRIGHT
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Copyright 2020-2025 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the Apache License 2.0 (the "License"). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file LICENSE in the source distribution or at
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L<https://www.openssl.org/source/license.html>.
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=cut
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