Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / BN_rand.3
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124.\" ========================================================================
125.\"
126.IX Title "BN_rand 3"
e3261593 127.TH BN_rand 3 "2012-01-04" "1.0.0f" "OpenSSL"
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128.\" For nroff, turn off justification. Always turn off hyphenation; it makes
129.\" way too many mistakes in technical documents.
130.if n .ad l
131.nh
984263bc 132.SH "NAME"
8b0cefbb 133BN_rand, BN_pseudo_rand \- generate pseudo\-random number
984263bc 134.SH "SYNOPSIS"
8b0cefbb 135.IX Header "SYNOPSIS"
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136.Vb 1
137\& #include <openssl/bn.h>
e257b235 138\&
984263bc 139\& int BN_rand(BIGNUM *rnd, int bits, int top, int bottom);
e257b235 140\&
984263bc 141\& int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom);
e257b235 142\&
984263bc 143\& int BN_rand_range(BIGNUM *rnd, BIGNUM *range);
e257b235 144\&
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145\& int BN_pseudo_rand_range(BIGNUM *rnd, BIGNUM *range);
146.Ve
147.SH "DESCRIPTION"
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148.IX Header "DESCRIPTION"
149\&\fIBN_rand()\fR generates a cryptographically strong pseudo-random number of
150\&\fBbits\fR bits in length and stores it in \fBrnd\fR. If \fBtop\fR is \-1, the
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151most significant bit of the random number can be zero. If \fBtop\fR is 0,
152it is set to 1, and if \fBtop\fR is 1, the two most significant bits of
153the number will be set to 1, so that the product of two such random
154numbers will always have 2*\fBbits\fR length. If \fBbottom\fR is true, the
155number will be odd.
156.PP
8b0cefbb 157\&\fIBN_pseudo_rand()\fR does the same, but pseudo-random numbers generated by
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158this function are not necessarily unpredictable. They can be used for
159non-cryptographic purposes and for certain purposes in cryptographic
160protocols, but usually not for key generation etc.
161.PP
8b0cefbb 162\&\fIBN_rand_range()\fR generates a cryptographically strong pseudo-random
984263bc 163number \fBrnd\fR in the range 0 <lt>= \fBrnd\fR < \fBrange\fR.
8b0cefbb 164\&\fIBN_pseudo_rand_range()\fR does the same, but is based on \fIBN_pseudo_rand()\fR,
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165and hence numbers generated by it are not necessarily unpredictable.
166.PP
8b0cefbb 167The \s-1PRNG\s0 must be seeded prior to calling \fIBN_rand()\fR or \fIBN_rand_range()\fR.
984263bc 168.SH "RETURN VALUES"
8b0cefbb 169.IX Header "RETURN VALUES"
984263bc 170The functions return 1 on success, 0 on error.
8b0cefbb 171The error codes can be obtained by \fIERR_get_error\fR\|(3).
984263bc 172.SH "SEE ALSO"
74dab6c2 173.IX Header "SEE ALSO"
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174\&\fIbn\fR\|(3), \fIERR_get_error\fR\|(3), \fIrand\fR\|(3),
175\&\fIRAND_add\fR\|(3), \fIRAND_bytes\fR\|(3)
176.SH "HISTORY"
74dab6c2 177.IX Header "HISTORY"
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178\&\fIBN_rand()\fR is available in all versions of SSLeay and OpenSSL.
179\&\fIBN_pseudo_rand()\fR was added in OpenSSL 0.9.5. The \fBtop\fR == \-1 case
180and the function \fIBN_rand_range()\fR were added in OpenSSL 0.9.6a.
181\&\fIBN_pseudo_rand_range()\fR was added in OpenSSL 0.9.6c.