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Diffstat (limited to 'crypto/openssl/doc/man3/RAND_DRBG_generate.pod')
-rw-r--r-- | crypto/openssl/doc/man3/RAND_DRBG_generate.pod | 88 |
1 files changed, 88 insertions, 0 deletions
diff --git a/crypto/openssl/doc/man3/RAND_DRBG_generate.pod b/crypto/openssl/doc/man3/RAND_DRBG_generate.pod new file mode 100644 index 000000000000..b39ee93f5142 --- /dev/null +++ b/crypto/openssl/doc/man3/RAND_DRBG_generate.pod @@ -0,0 +1,88 @@ +=pod + +=head1 NAME + +RAND_DRBG_generate, +RAND_DRBG_bytes +- generate random bytes using the given drbg instance + +=head1 SYNOPSIS + + #include <openssl/rand_drbg.h> + + int RAND_DRBG_generate(RAND_DRBG *drbg, + unsigned char *out, size_t outlen, + int prediction_resistance, + const unsigned char *adin, size_t adinlen); + + int RAND_DRBG_bytes(RAND_DRBG *drbg, + unsigned char *out, size_t outlen); + + +=head1 DESCRIPTION + +RAND_DRBG_generate() generates B<outlen> random bytes using the given +DRBG instance B<drbg> and stores them in the buffer at B<out>. + +Before generating the output, the DRBG instance checks whether the maximum +number of generate requests (I<reseed interval>) or the maximum timespan +(I<reseed time interval>) since its last seeding have been reached. +If this is the case, the DRBG reseeds automatically. +Additionally, an immediate reseeding can be requested by setting the +B<prediction_resistance> flag to 1. See NOTES section for more details. + +The caller can optionally provide additional data to be used for reseeding +by passing a pointer B<adin> to a buffer of length B<adinlen>. +This additional data is mixed into the internal state of the random +generator but does not contribute to the entropy count. +The additional data can be omitted by setting B<adin> to NULL and +B<adinlen> to 0; + +RAND_DRBG_bytes() generates B<outlen> random bytes using the given +DRBG instance B<drbg> and stores them in the buffer at B<out>. +This function is a wrapper around the RAND_DRBG_generate() call, +which collects some additional data from low entropy sources +(e.g., a high resolution timer) and calls +RAND_DRBG_generate(drbg, out, outlen, 0, adin, adinlen). + + +=head1 RETURN VALUES + +RAND_DRBG_generate() and RAND_DRBG_bytes() return 1 on success, +and 0 on failure. + +=head1 NOTES + +The I<reseed interval> and I<reseed time interval> of the B<drbg> are set to +reasonable default values, which in general do not have to be adjusted. +If necessary, they can be changed using L<RAND_DRBG_set_reseed_interval(3)> +and L<RAND_DRBG_set_reseed_time_interval(3)>, respectively. + +A request for prediction resistance can only be satisfied by pulling fresh +entropy from one of the approved entropy sources listed in section 5.5.2 of +[NIST SP 800-90C]. +Since the default DRBG implementation does not have access to such an approved +entropy source, a request for prediction resistance will always fail. +In other words, prediction resistance is currently not supported yet by the DRBG. + +=head1 HISTORY + +The RAND_DRBG functions were added in OpenSSL 1.1.1. + +=head1 SEE ALSO + +L<RAND_bytes(3)>, +L<RAND_DRBG_set_reseed_interval(3)>, +L<RAND_DRBG_set_reseed_time_interval(3)>, +L<RAND_DRBG(7)> + +=head1 COPYRIGHT + +Copyright 2017-2018 The OpenSSL Project Authors. All Rights Reserved. + +Licensed under the OpenSSL license (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 +L<https://www.openssl.org/source/license.html>. + +=cut |