4871fa49cd
With the introduction of RAND_poll_ex(), the `RAND_add()` calls were replaced by meaningless cb(...). This commit changes the 'cb(...)' calls back to 'rand_add(...)' calls by changing the signature as follows: -int RAND_poll_ex(RAND_poll_fn cb, void *arg); +int RAND_poll_ex(RAND_poll_cb rand_add, void *arg); Changed the function typedef name to 'RAND_poll_cb' to emphasize the fact that the function type represents a callback function. Reviewed-by: Paul Dale <paul.dale@oracle.com> Reviewed-by: Rich Salz <rsalz@openssl.org> (Merged from https://github.com/openssl/openssl/pull/4266)
100 lines
3.4 KiB
Text
100 lines
3.4 KiB
Text
=pod
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=head1 NAME
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RAND_add, RAND_poll, RAND_poll_ex, RAND_poll_cb,
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RAND_seed, RAND_status, RAND_event, RAND_screen
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- add randomness to the PRNG or get its status
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=head1 SYNOPSIS
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#include <openssl/rand.h>
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int RAND_status(void);
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typedef void (*RAND_poll_cb)(void *arg,
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const void *buf, int num, double randomness);
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int RAND_poll_ex(RAND_poll_cb cb, void *arg);
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int RAND_poll();
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void RAND_add(const void *buf, int num, double randomness);
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void RAND_seed(const void *buf, int num);
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Deprecated:
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#if OPENSSL_API_COMPAT < 0x10100000L
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int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam);
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void RAND_screen(void);
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#endif
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=head1 DESCRIPTION
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Random numbers are a vital part of cryptography, including key generation,
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creating salts, etc., and software-based
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generators must be "seeded" with external randomness before they can be
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used as a cryptographically-secure pseudo-random number generator (CSPRNG).
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The availability of common hardware with special instructions and
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modern operating systems, which may use items such as interrupt jitter
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and network packet timings, can be reasonable sources of seeding material.
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RAND_status() indicates whether or not the CSPRNG has been sufficiently
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seeded. If not, functions such as RAND_bytes(3) will fail.
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RAND_poll_ex() uses the system's capabilities to obtain a buffer
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containing random bits which can then be used to seed a CSPRNG. The
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exact features used depends on how OpenSSL was configured, and a summary
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can be displayed with the OpenSSL L<version(1)> command. This function
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is normally called as needed by the CSPRNG. The B<arg> parameter is an
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arbitrary pointer which will be passed as an argument to the callback.
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The B<cb> function is called each time there is data to add.
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RAND_poll() invokes RAND_poll_ex() with B<cb> and B<arg> set so that it
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will call RAND_add(), to add the randomness to the global CSPRNG.
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RAND_add() mixes the B<num> bytes at B<buf> into the PRNG state.
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The B<randomness> argument is an estimate of how much randomness is
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contained in
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B<buf>, in bytes, and should be a number between zero and B<num>.
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Details about sources of randomness and how to estimate their randomness
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can be found in the literature; for example NIST SP 800-90B.
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The content of B<buf> cannot be recovered from subsequent CSPRNG output.
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This function will not normally be needed, as RAND_poll() should have been
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configured to do the appropriate seeding for the local platform.
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Applications that need to keep random state in an external file should
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use L<RAND_load_file(3)>.
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RAND_seed() is equivalent to RAND_add() with B<randomness> set to B<num>.
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RAND_event() and RAND_screen() are equivalent to RAND_poll().
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=head1 RETURN VALUES
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RAND_status() returns 1 if the CSPRNG has been seeded
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with enough data, 0 otherwise.
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RAND_poll() returns 1 if it generated seed data, 0 otherwise.
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RAND_event() returns RAND_status().
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The other functions do not return values.
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=head1 HISTORY
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RAND_event() and RAND_screen() were deprecated in OpenSSL 1.1.0 and should
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not be used.
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=head1 SEE ALSO
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L<RAND_bytes(3)>, L<RAND_egd(3)>,
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L<RAND_load_file(3)>
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=head1 COPYRIGHT
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Copyright 2000-2017 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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