.rn '' }`
''' $RCSfile$$Revision$$Date$
'''
''' $Log$
'''
.de Sh
.br
.if t .Sp
.ne 5
.PP
\fB\\$1\fR
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'''
'''
'''     Set up \*(-- to give an unbreakable dash;
'''     string Tr holds user defined translation string.
'''     Bell System Logo is used as a dummy character.
'''
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.ie n \{\
.ds -- \(*W-
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.ds L" ""
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'''   \*(M", \*(S", \*(N" and \*(T" are the equivalent of
'''   \*(L" and \*(R", except that they are used on ".xx" lines,
'''   such as .IP and .SH, which do another additional levels of
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.ds M" """
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.el\{\
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.\"	If the F register is turned on, we'll generate
.\"	index entries out stderr for the following things:
.\"		TH	Title 
.\"		SH	Header
.\"		Sh	Subsection 
.\"		Ip	Item
.\"		X<>	Xref  (embedded
.\"	Of course, you have to process the output yourself
.\"	in some meaninful fashion.
.if \nF \{
.de IX
.tm Index:\\$1\t\\n%\t"\\$2"
..
.nr % 0
.rr F
.\}
.TH BN_rand 3 "0.9.7d" "2/Sep/2004" "OpenSSL"
.UC
.if n .hy 0
.if n .na
.ds C+ C\v'-.1v'\h'-1p'\s-2+\h'-1p'+\s0\v'.1v'\h'-1p'
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'if n "\c
'if t \\&\\$1\c
'if n \\&\\$1\c
'if n \&"
\\&\\$2 \\$3 \\$4 \\$5 \\$6 \\$7
'.ft R
..
.\" @(#)ms.acc 1.5 88/02/08 SMI; from UCB 4.2
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.bd B 3
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.	\" simple accents for nroff and troff
.if n \{\
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.	\" troff and (daisy-wheel) nroff accents
.ds : \\k:\h'-(\\n(.wu*8/10-\*(#H+.1m+\*(#F)'\v'-\*(#V'\z.\h'.2m+\*(#F'.\h'|\\n:u'\v'\*(#V'
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.ds Th \*(#[\s+2I\s-2\h'-\w'I'u*3/5'\v'-.3m'o\v'.3m'\*(#]
.ds ae a\h'-(\w'a'u*4/10)'e
.ds Ae A\h'-(\w'A'u*4/10)'E
.ds oe o\h'-(\w'o'u*4/10)'e
.ds Oe O\h'-(\w'O'u*4/10)'E
.	\" corrections for vroff
.if v .ds ~ \\k:\h'-(\\n(.wu*9/10-\*(#H)'\s-2\u~\d\s+2\h'|\\n:u'
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\{\
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.rm #[ #] #H #V #F C
.SH "NAME"
BN_rand, BN_pseudo_rand \- generate pseudo-random number
.SH "SYNOPSIS"
.PP
.Vb 1
\& #include <openssl/bn.h>
.Ve
.Vb 1
\& int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
.Ve
.Vb 1
\& int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
.Ve
.Vb 1
\& int BN_rand_range(BIGNUM *rnd, BIGNUM *range);
.Ve
.Vb 1
\& int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);
.Ve
.SH "DESCRIPTION"
\fIBN_rand()\fR generates a cryptographically strong pseudo-random number of
\fBbits\fR bits in length and stores it in \fBrnd\fR. If \fBtop\fR is \-1, the
most significant bit of the random number can be zero. If \fBtop\fR is 0,
it is set to 1, and if \fBtop\fR is 1, 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 2*\fBbits\fR length.  If \fBbottom\fR is true, the
number will be odd.
.PP
\fIBN_pseudo_rand()\fR does the same, but pseudo-random numbers generated by
this function 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
\fIBN_rand_range()\fR generates a cryptographically strong pseudo-random
number \fBrnd\fR in the range 0 <lt>= \fBrnd\fR < \fBrange\fR.
\fIBN_pseudo_rand_range()\fR does the same, but is based on \fIBN_pseudo_rand()\fR,
and hence numbers generated by it are not necessarily unpredictable.
.PP
The PRNG must be seeded prior to calling \fIBN_rand()\fR or \fIBN_rand_range()\fR.
.SH "RETURN VALUES"
The functions return 1 on success, 0 on error.
The error codes can be obtained by ERR_get_error(3).
.SH "SEE ALSO"
bn(3), ERR_get_error(3), rand(3),
RAND_add(3), RAND_bytes(3)
.SH "HISTORY"
\fIBN_rand()\fR is available in all versions of SSLeay and OpenSSL.
\fIBN_pseudo_rand()\fR was added in OpenSSL 0.9.5. The \fBtop\fR == \-1 case
and the function \fIBN_rand_range()\fR were added in OpenSSL 0.9.6a.
\fIBN_pseudo_rand_range()\fR was added in OpenSSL 0.9.6c.

.rn }` ''
.IX Title "BN_rand 3"
.IX Name "BN_rand, BN_pseudo_rand - generate pseudo-random number"

.IX Header "NAME"

.IX Header "SYNOPSIS"

.IX Header "DESCRIPTION"

.IX Header "RETURN VALUES"

.IX Header "SEE ALSO"

.IX Header "HISTORY"