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Diffstat (limited to 'doc/man3/RAND_add.pod')
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diff --git a/doc/man3/RAND_add.pod b/doc/man3/RAND_add.pod new file mode 100644 index 000000000000..b6753fd2ed0b --- /dev/null +++ b/doc/man3/RAND_add.pod @@ -0,0 +1,104 @@ +=pod + +=head1 NAME + +RAND_add, RAND_poll, RAND_seed, RAND_status, RAND_event, RAND_screen, +RAND_keep_random_devices_open +- add randomness to the PRNG or get its status + +=head1 SYNOPSIS + + #include <openssl/rand.h> + + int RAND_status(void); + int RAND_poll(); + + void RAND_add(const void *buf, int num, double randomness); + void RAND_seed(const void *buf, int num); + + void RAND_keep_random_devices_open(int keep); + +Deprecated: + + #if OPENSSL_API_COMPAT < 0x10100000L + int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam); + void RAND_screen(void); + #endif + +=head1 DESCRIPTION + +These functions can be used to seed the random generator and to check its +seeded state. +In general, manual (re-)seeding of the default OpenSSL random generator +(L<RAND_OpenSSL(3)>) is not necessary (but allowed), since it does (re-)seed +itself automatically using trusted system entropy sources. +This holds unless the default RAND_METHOD has been replaced or OpenSSL was +built with automatic reseeding disabled, see L<RAND(7)> for more details. + +RAND_status() indicates whether or not the random generator has been sufficiently +seeded. If not, functions such as L<RAND_bytes(3)> will fail. + +RAND_poll() uses the system's capabilities to seed the random generator using +random input obtained from polling various trusted entropy sources. +The default choice of the entropy source can be modified at build time, +see L<RAND(7)> for more details. + +RAND_add() mixes the B<num> bytes at B<buf> into the internal state +of the random generator. +This function will not normally be needed, as mentioned above. +The B<randomness> argument is an estimate of how much randomness is +contained in +B<buf>, in bytes, and should be a number between zero and B<num>. +Details about sources of randomness and how to estimate their randomness +can be found in the literature; for example [NIST SP 800-90B]. +The content of B<buf> cannot be recovered from subsequent random generator output. +Applications that intend to save and restore random state in an external file +should consider using L<RAND_load_file(3)> instead. + +RAND_seed() is equivalent to RAND_add() with B<randomness> set to B<num>. + +RAND_keep_random_devices_open() is used to control file descriptor +usage by the random seed sources. Some seed sources maintain open file +descriptors by default, which allows such sources to operate in a +chroot(2) jail without the associated device nodes being available. When +the B<keep> argument is zero, this call disables the retention of file +descriptors. Conversely, a non-zero argument enables the retention of +file descriptors. This function is usually called during initialization +and it takes effect immediately. + +RAND_event() and RAND_screen() are equivalent to RAND_poll() and exist +for compatibility reasons only. See HISTORY section below. + +=head1 RETURN VALUES + +RAND_status() returns 1 if the random generator has been seeded +with enough data, 0 otherwise. + +RAND_poll() returns 1 if it generated seed data, 0 otherwise. + +RAND_event() returns RAND_status(). + +The other functions do not return values. + +=head1 HISTORY + +RAND_event() and RAND_screen() were deprecated in OpenSSL 1.1.0 and should +not be used. + +=head1 SEE ALSO + +L<RAND_bytes(3)>, +L<RAND_egd(3)>, +L<RAND_load_file(3)>, +L<RAND(7)> + +=head1 COPYRIGHT + +Copyright 2000-2018 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 |