Upgrade to OpenSSL 0.9.8h.
[dragonfly.git] / secure / lib / libcrypto / man / BN_rand.3
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129.\" ========================================================================
130.\"
131.IX Title "BN_rand 3"
aac4ff6f 132.TH BN_rand 3 "2008-09-06" "0.9.8h" "OpenSSL"
984263bc 133.SH "NAME"
8b0cefbb 134BN_rand, BN_pseudo_rand \- generate pseudo\-random number
984263bc 135.SH "SYNOPSIS"
8b0cefbb 136.IX Header "SYNOPSIS"
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137.Vb 1
138\& #include <openssl/bn.h>
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139.Ve
140.PP
141.Vb 1
984263bc 142\& int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
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143.Ve
144.PP
145.Vb 1
984263bc 146\& int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
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147.Ve
148.PP
149.Vb 1
984263bc 150\& int BN_rand_range(BIGNUM *rnd, BIGNUM *range);
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151.Ve
152.PP
153.Vb 1
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154\& int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);
155.Ve
156.SH "DESCRIPTION"
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157.IX Header "DESCRIPTION"
158\&\fIBN_rand()\fR generates a cryptographically strong pseudo-random number of
159\&\fBbits\fR bits in length and stores it in \fBrnd\fR. If \fBtop\fR is \-1, the
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160most significant bit of the random number can be zero. If \fBtop\fR is 0,
161it is set to 1, and if \fBtop\fR is 1, the two most significant bits of
162the number will be set to 1, so that the product of two such random
163numbers will always have 2*\fBbits\fR length. If \fBbottom\fR is true, the
164number will be odd.
165.PP
8b0cefbb 166\&\fIBN_pseudo_rand()\fR does the same, but pseudo-random numbers generated by
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167this function are not necessarily unpredictable. They can be used for
168non-cryptographic purposes and for certain purposes in cryptographic
169protocols, but usually not for key generation etc.
170.PP
8b0cefbb 171\&\fIBN_rand_range()\fR generates a cryptographically strong pseudo-random
984263bc 172number \fBrnd\fR in the range 0 <lt>= \fBrnd\fR < \fBrange\fR.
8b0cefbb 173\&\fIBN_pseudo_rand_range()\fR does the same, but is based on \fIBN_pseudo_rand()\fR,
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174and hence numbers generated by it are not necessarily unpredictable.
175.PP
8b0cefbb 176The \s-1PRNG\s0 must be seeded prior to calling \fIBN_rand()\fR or \fIBN_rand_range()\fR.
984263bc 177.SH "RETURN VALUES"
8b0cefbb 178.IX Header "RETURN VALUES"
984263bc 179The functions return 1 on success, 0 on error.
8b0cefbb 180The error codes can be obtained by \fIERR_get_error\fR\|(3).
984263bc 181.SH "SEE ALSO"
74dab6c2 182.IX Header "SEE ALSO"
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183\&\fIbn\fR\|(3), \fIERR_get_error\fR\|(3), \fIrand\fR\|(3),
184\&\fIRAND_add\fR\|(3), \fIRAND_bytes\fR\|(3)
185.SH "HISTORY"
74dab6c2 186.IX Header "HISTORY"
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187\&\fIBN_rand()\fR is available in all versions of SSLeay and OpenSSL.
188\&\fIBN_pseudo_rand()\fR was added in OpenSSL 0.9.5. The \fBtop\fR == \-1 case
189and the function \fIBN_rand_range()\fR were added in OpenSSL 0.9.6a.
190\&\fIBN_pseudo_rand_range()\fR was added in OpenSSL 0.9.6c.