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.\" ========================================================================
.\"
.IX Title "RAND_BYTES 3SSL"
.TH RAND_BYTES 3SSL "2018-11-28" "1.1.0j" "OpenSSL"
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
RAND_bytes, RAND_pseudo_bytes \- generate random data
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
.Vb 1
\& #include <openssl/rand.h>
\&
\& int RAND_bytes(unsigned char *buf, int num);
.Ve
.PP
Deprecated:
.PP
.Vb 3
\& #if OPENSSL_API_COMPAT < 0x10100000L
\& int RAND_pseudo_bytes(unsigned char *buf, int num);
\& #endif
.Ve
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fIRAND_bytes()\fR puts \fBnum\fR cryptographically strong pseudo-random bytes
into \fBbuf\fR. An error occurs if the \s-1PRNG\s0 has not been seeded with
enough randomness to ensure an unpredictable byte sequence.
.PP
\&\fIRAND_pseudo_bytes()\fR has been deprecated. Users should use \fIRAND_bytes()\fR instead.
\&\fIRAND_pseudo_bytes()\fR puts \fBnum\fR pseudo-random bytes into \fBbuf\fR.
Pseudo-random byte sequences generated by \fIRAND_pseudo_bytes()\fR 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.
.PP
The contents of \fBbuf\fR is mixed into the entropy pool before retrieving
the new pseudo-random bytes unless disabled at compile time (see \s-1FAQ\s0).
.SH "RETURN VALUES"
.IX Header "RETURN VALUES"
\&\fIRAND_bytes()\fR returns 1 on success, 0 otherwise. The error code can be
obtained by \fIERR_get_error\fR\|(3). \fIRAND_pseudo_bytes()\fR returns 1 if the
bytes generated are cryptographically strong, 0 otherwise. Both
functions return \-1 if they are not supported by the current \s-1RAND\s0
method.
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIrand\fR\|(3), \fIERR_get_error\fR\|(3),
\&\fIRAND_add\fR\|(3)
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2000\-2016 The OpenSSL Project Authors. All Rights Reserved.
.PP
Licensed under the OpenSSL license (the \*(L"License\*(R").  You may not use
this file except in compliance with the License.  You can obtain a copy
in the file \s-1LICENSE\s0 in the source distribution or at
<https://www.openssl.org/source/license.html>.