128 lines
3.9 KiB
Plaintext
128 lines
3.9 KiB
Plaintext
=pod
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=head1 NAME
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RAND_DRBG_new,
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RAND_DRBG_secure_new,
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RAND_DRBG_set,
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RAND_DRBG_set_defaults,
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RAND_DRBG_instantiate,
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RAND_DRBG_uninstantiate,
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RAND_DRBG_free
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- initialize and cleanup a RAND_DRBG instance
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=head1 SYNOPSIS
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#include <openssl/rand_drbg.h>
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RAND_DRBG *RAND_DRBG_new(int type,
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unsigned int flags,
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RAND_DRBG *parent);
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RAND_DRBG *RAND_DRBG_secure_new(int type,
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unsigned int flags,
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RAND_DRBG *parent);
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int RAND_DRBG_set(RAND_DRBG *drbg,
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int type, unsigned int flags);
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int RAND_DRBG_set_defaults(int type, unsigned int flags);
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int RAND_DRBG_instantiate(RAND_DRBG *drbg,
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const unsigned char *pers, size_t perslen);
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int RAND_DRBG_uninstantiate(RAND_DRBG *drbg);
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void RAND_DRBG_free(RAND_DRBG *drbg);
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=head1 DESCRIPTION
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RAND_DRBG_new() and RAND_DRBG_secure_new()
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create a new DRBG instance of the given B<type>, allocated from the heap resp.
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the secure heap
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(using OPENSSL_zalloc() resp. OPENSSL_secure_zalloc()).
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RAND_DRBG_set() initializes the B<drbg> with the given B<type> and B<flags>.
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RAND_DRBG_set_defaults() sets the default B<type> and B<flags> for new DRBG
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instances.
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Currently, all DRBG types are based on AES-CTR, so B<type> can be one of the
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following values: NID_aes_128_ctr, NID_aes_192_ctr, NID_aes_256_ctr.
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Before the DRBG can be used to generate random bits, it is necessary to set
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its type and to instantiate it.
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The optional B<flags> argument specifies a set of bit flags which can be
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joined using the | operator. Currently, the only flag is
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RAND_DRBG_FLAG_CTR_NO_DF, which disables the use of the derivation function
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ctr_df. For an explanation, see [NIST SP 800-90A Rev. 1].
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If a B<parent> instance is specified then this will be used instead of
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the default entropy source for reseeding the B<drbg>. It is said that the
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B<drbg> is I<chained> to its B<parent>.
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For more information, see the NOTES section.
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RAND_DRBG_instantiate()
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seeds the B<drbg> instance using random input from trusted entropy sources.
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Optionally, a personalization string B<pers> of length B<perslen> can be
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specified.
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To omit the personalization string, set B<pers>=NULL and B<perslen>=0;
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RAND_DRBG_uninstantiate()
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clears the internal state of the B<drbg> and puts it back in the
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uninstantiated state.
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=head1 RETURN VALUES
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RAND_DRBG_new() and RAND_DRBG_secure_new() return a pointer to a DRBG
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instance allocated on the heap, resp. secure heap.
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RAND_DRBG_set(),
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RAND_DRBG_instantiate(), and
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RAND_DRBG_uninstantiate()
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return 1 on success, and 0 on failure.
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RAND_DRBG_free() does not return a value.
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=head1 NOTES
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The DRBG design supports I<chaining>, which means that a DRBG instance can
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use another B<parent> DRBG instance instead of the default entropy source
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to obtain fresh random input for reseeding, provided that B<parent> DRBG
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instance was properly instantiated, either from a trusted entropy source,
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or from yet another parent DRBG instance.
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For a detailed description of the reseeding process, see L<RAND_DRBG(7)>.
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The default DRBG type and flags are applied only during creation of a DRBG
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instance.
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To ensure that they are applied to the global and thread-local DRBG instances
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(<master>, resp. <public> and <private>), it is necessary to call
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RAND_DRBG_set_defaults() before creating any thread and before calling any
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cryptographic routines that obtain random data directly or indirectly.
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=head1 SEE ALSO
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L<OPENSSL_zalloc(3)>,
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L<OPENSSL_secure_zalloc(3)>,
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L<RAND_DRBG_generate(3)>,
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L<RAND_DRBG(7)>
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=head1 HISTORY
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The RAND_DRBG functions were added in OpenSSL 1.1.1.
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=head1 COPYRIGHT
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Copyright 2017-2020 The OpenSSL Project Authors. All Rights Reserved.
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Licensed under the OpenSSL license (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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