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.\" $OpenBSD: BN_rand.3,v 1.18 2021/11/30 18:34:35 tb Exp $
.\" full merge up to: OpenSSL 05ea606a May 20 20:52:46 2016 -0400
.\" selective merge up to: OpenSSL df75c2bf Dec 9 01:02:36 2018 +0100
.\"
.\" This file was written by Ulf Moeller <ulf@openssl.org>.
.\" Copyright (c) 2000, 2001, 2002, 2013, 2015 The OpenSSL Project.
.\" All rights reserved.
.\"
.\" Redistribution and use in source and binary forms, with or without
.\" modification, are permitted provided that the following conditions
.\" are met:
.\"
.\" 1. Redistributions of source code must retain the above copyright
.\" notice, this list of conditions and the following disclaimer.
.\"
.\" 2. Redistributions in binary form must reproduce the above copyright
.\" notice, this list of conditions and the following disclaimer in
.\" the documentation and/or other materials provided with the
.\" distribution.
.\"
.\" 3. All advertising materials mentioning features or use of this
.\" software must display the following acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
.\"
.\" 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
.\" endorse or promote products derived from this software without
.\" prior written permission. For written permission, please contact
.\" openssl-core@openssl.org.
.\"
.\" 5. Products derived from this software may not be called "OpenSSL"
.\" nor may "OpenSSL" appear in their names without prior written
.\" permission of the OpenSSL Project.
.\"
.\" 6. Redistributions of any form whatsoever must retain the following
.\" acknowledgment:
.\" "This product includes software developed by the OpenSSL Project
.\" for use in the OpenSSL Toolkit (http://www.openssl.org/)"
.\"
.\" THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
.\" EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
.\" ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
.\" SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
.\" NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
.\" LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\"
.Dd $Mdocdate: November 30 2021 $
.Dt BN_RAND 3
.Os
.Sh NAME
.Nm BN_rand ,
.Nm BN_rand_range ,
.Nm BN_pseudo_rand ,
.Nm BN_pseudo_rand_range
.Nd generate pseudo-random number
.Sh SYNOPSIS
.In openssl/bn.h
.Ft int
.Fo BN_rand
.Fa "BIGNUM *rnd"
.Fa "int bits"
.Fa "int top"
.Fa "int bottom"
.Fc
.Ft int
.Fo BN_rand_range
.Fa "BIGNUM *rnd"
.Fa "const BIGNUM *range"
.Fc
.Sh DESCRIPTION
.Fn BN_rand
generates a cryptographically strong pseudo-random number of
.Fa bits
in length and stores it in
.Fa rnd .
If
.Fa top
is
.Dv BN_RAND_TOP_ANY ,
the most significant bit of the random number can be zero.
If
.Fa top
is
.Dv BN_RAND_TOP_ONE ,
the most significant bit is set to 1, and if
.Fa top
is
.Dv BN_RAND_TOP_TWO ,
the two most significant bits of the number will be set to 1, so
that the product of two such random numbers will always have
.Pf 2* Fa bits
length.
If
.Fa bottom
is
.Dv BN_RAND_BOTTOM_ODD ,
the number will be odd;
if it is
.Dv BN_RAND_BOTTOM_ANY ,
it can be odd or even.
The value of
.Fa bits
must be zero or greater.
If
.Fa bits
is +1 then
.Fa top
cannot be
.Dv BN_RAND_TOP_TWO .
.Pp
.Fn BN_rand_range
generates a cryptographically strong pseudo-random number
.Fa rnd
in the range 0 <=
.Fa rnd No < Fa range .
.Pp
.Fn BN_pseudo_rand
is a deprecated alias for
.Fn BN_rand ,
and
.Fn BN_pseudo_rand_range
for
.Fn BN_rand_range .
.Sh RETURN VALUES
The functions return 1 on success, 0 on error.
The error codes can be obtained by
.Xr ERR_get_error 3 .
.Sh SEE ALSO
.Xr BN_new 3
.Sh HISTORY
.Fn BN_rand
first appeared in SSLeay 0.5.1 and has been available since
.Ox 2.4 .
.Pp
The
.Fa top
== -1 case and the function
.Fn BN_rand_range
first appeared in OpenSSL 0.9.6a and have been available since
.Ox 3.0 .
|
