=head1 NAME
-RAND_add, RAND_poll, RAND_seed, RAND_status, RAND_event, RAND_screen
+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()
+ int RAND_poll();
void RAND_add(const void *buf, int num, double randomness);
void RAND_seed(const void *buf, int num);
-Deprecated:
+ void RAND_keep_random_devices_open(int keep);
+
+Deprecated since OpenSSL 1.1.0, can be hidden entirely by defining
+B<OPENSSL_API_COMPAT> with a suitable version value, see
+L<openssl_user_macros(7)>:
- #if OPENSSL_API_COMPAT < 0x10100000L
int RAND_event(UINT iMsg, WPARAM wParam, LPARAM lParam);
void RAND_screen(void);
- #endif
=head1 DESCRIPTION
-Random numbers are a vital part of cryptography, including key generation,
-creating salts, etc., and software-based
-generators must be "seeded" with external randomness before they can be
-used as a cryptographically-secure pseudo-random number generator (CSPRNG).
-The availability of common hardware with special instructions and
-modern operating systems, which may use items such as interrupt jitter
-and network packet timings, can be reasonable sources of seeding material.
-
-RAND_status() indicates whether or not the CSPRNG has been sufficiently
-seeded. If not, functions such as RAND_bytes(3) will fail.
-
-RAND_poll() uses the current capabilities to seed the CSPRNG. The
-exact features used depends on how OpenSSL was configured, and can
-be displayed with the OpenSSL L<version(1)> command. This function is
-normally called automatically during OpenSSL initialization, but
-can be called by the application to reseed the CSPRNG.
-
-RAND_add() mixes the B<num> bytes at B<buf> into the PRNG state.
+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 CSPRNG output.
-This function will not normally be needed, as RAND_poll() should have been
-configured to do the appropriate seeding for the local platform.
-Applications that need to keep random state in an external file should
-use L<RAND_load_file(3)>.
+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.
+
+NOTE: In FIPS mode, random data provided by the application is not considered to
+be a trusted entropy source. It is mixed into the internal state of the RNG as
+additional data only and this does not count as a full reseed.
+For more details, see L<RAND_DRBG(7)>.
RAND_seed() is equivalent to RAND_add() with B<randomness> set to B<num>.
-RAND_event() and RAND_screen() are equivalent to RAND_poll().
+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 nonzero argument enables the retention of
+file descriptors. This function is usually called during initialization
+and it takes effect immediately. This capability only applies to the default
+provider.
+
+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 CSPRNG has been seeded
+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.
The other functions do not return values.
+=head1 SEE ALSO
+
+L<RAND_bytes(3)>,
+L<RAND_egd(3)>,
+L<RAND_load_file(3)>,
+L<RAND(7)>
+L<RAND_DRBG(7)>
+
=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)>
-
=head1 COPYRIGHT
-Copyright 2000-2017 The OpenSSL Project Authors. All Rights Reserved.
+Copyright 2000-2019 The OpenSSL Project Authors. All Rights Reserved.
-Licensed under the OpenSSL license (the "License"). You may not use
+Licensed under the Apache License 2.0 (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>.
projects / openssl.git / blobdiff