openssl/doc/crypto/RAND_bytes.pod
Richard Levitte 6859cf7459 It makes more sense to refer to specific function manuals than the concept
manual when the specific function is refered to in the current manual text.
This correction was originally introduced in OpenBSD's tracking of OpenSSL.
2002-09-25 13:33:28 +00:00

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=pod
=head1 NAME
RAND_bytes, RAND_pseudo_bytes - generate random data
=head1 SYNOPSIS
#include <openssl/rand.h>
int RAND_bytes(unsigned char *buf, int num);
int RAND_pseudo_bytes(unsigned char *buf, int num);
=head1 DESCRIPTION
RAND_bytes() puts B<num> cryptographically strong pseudo-random bytes
into B<buf>. An error occurs if the PRNG has not been seeded with
enough randomness to ensure an unpredictable byte sequence.
RAND_pseudo_bytes() puts B<num> pseudo-random bytes into B<buf>.
Pseudo-random byte sequences generated by RAND_pseudo_bytes() will be
unique if they are of sufficient length, but are not necessarily
unpredictable. They can be used for non-cryptographic purposes and for
certain purposes in cryptographic protocols, but usually not for key
generation etc.
=head1 RETURN VALUES
RAND_bytes() returns 1 on success, 0 otherwise. The error code can be
obtained by L<ERR_get_error(3)|ERR_get_error(3)>. RAND_pseudo_bytes() returns 1 if the
bytes generated are cryptographically strong, 0 otherwise. Both
functions return -1 if they are not supported by the current RAND
method.
=head1 SEE ALSO
L<rand(3)|rand(3)>, L<ERR_get_error(3)|ERR_get_error(3)>,
L<RAND_add(3)|RAND_add(3)>
=head1 HISTORY
RAND_bytes() is available in all versions of SSLeay and OpenSSL. It
has a return value since OpenSSL 0.9.5. RAND_pseudo_bytes() was added
in OpenSSL 0.9.5.
=cut