2
0
mirror of https://github.com/openssl/openssl.git synced 2024-12-27 06:21:43 +08:00
openssl/doc/crypto/rand.pod
Rich Salz a528d4f0a9 Remove SSLeay history, etc., from docs
If something was "present in all versions" of SSLeay, or if it was
added to a version of SSLeay (and therefore predates OpenSSL),
remove mention of it.  Documentation history now starts with OpenSSL.

Remove mention of all history before OpenSSL 0.9.8, inclusive.

Remove all AUTHOR sections.

Reviewed-by: Tim Hudson <tjh@openssl.org>
2015-10-28 17:23:51 -04:00

74 lines
2.3 KiB
Plaintext

=pod
=head1 NAME
rand - pseudo-random number generator
=head1 SYNOPSIS
#include <openssl/rand.h>
int RAND_set_rand_engine(ENGINE *engine);
int RAND_bytes(unsigned char *buf, int num);
int RAND_pseudo_bytes(unsigned char *buf, int num);
void RAND_seed(const void *buf, int num);
void RAND_add(const void *buf, int num, int entropy);
int RAND_status(void);
int RAND_load_file(const char *file, long max_bytes);
int RAND_write_file(const char *file);
const char *RAND_file_name(char *file, size_t num);
int RAND_egd(const char *path);
void RAND_set_rand_method(const RAND_METHOD *meth);
const RAND_METHOD *RAND_get_rand_method(void);
RAND_METHOD *RAND_OpenSSL(void);
void RAND_cleanup(void);
/* For Win32 only */
void RAND_screen(void);
int RAND_event(UINT, WPARAM, LPARAM);
=head1 DESCRIPTION
Since the introduction of the ENGINE API, the recommended way of controlling
default implementations is by using the ENGINE API functions. The default
B<RAND_METHOD>, as set by RAND_set_rand_method() and returned by
RAND_get_rand_method(), is only used if no ENGINE has been set as the default
"rand" implementation. Hence, these two functions are no longer the recommended
way to control defaults.
If an alternative B<RAND_METHOD> implementation is being used (either set
directly or as provided by an ENGINE module), then it is entirely responsible
for the generation and management of a cryptographically secure PRNG stream. The
mechanisms described below relate solely to the software PRNG implementation
built in to OpenSSL and used by default.
These functions implement a cryptographically secure pseudo-random
number generator (PRNG). It is used by other library functions for
example to generate random keys, and applications can use it when they
need randomness.
A cryptographic PRNG must be seeded with unpredictable data such as
mouse movements or keys pressed at random by the user. This is
described in L<RAND_add(3)>. Its state can be saved in a seed file
(see L<RAND_load_file(3)>) to avoid having to go through the
seeding process whenever the application is started.
L<RAND_bytes(3)> describes how to obtain random data from the
PRNG.
=head1 SEE ALSO
L<BN_rand(3)>, L<RAND_add(3)>,
L<RAND_load_file(3)>, L<RAND_egd(3)>,
L<RAND_bytes(3)>,
L<RAND_set_rand_method(3)>,
L<RAND_cleanup(3)>
=cut