Update files for OpenSSL-1.0.0f import.
[dragonfly.git] / secure / lib / libcrypto / man / RAND_bytes.3
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124.\" ========================================================================
125.\"
126.IX Title "RAND_bytes 3"
e3261593 127.TH RAND_bytes 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.
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131.nh
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132.SH "NAME"
133RAND_bytes, RAND_pseudo_bytes \- generate random data
134.SH "SYNOPSIS"
8b0cefbb 135.IX Header "SYNOPSIS"
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136.Vb 1
137\& #include <openssl/rand.h>
e257b235 138\&
984263bc 139\& int RAND_bytes(unsigned char *buf, int num);
e257b235 140\&
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141\& int RAND_pseudo_bytes(unsigned char *buf, int num);
142.Ve
143.SH "DESCRIPTION"
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144.IX Header "DESCRIPTION"
145\&\fIRAND_bytes()\fR puts \fBnum\fR cryptographically strong pseudo-random bytes
146into \fBbuf\fR. An error occurs if the \s-1PRNG\s0 has not been seeded with
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147enough randomness to ensure an unpredictable byte sequence.
148.PP
8b0cefbb 149\&\fIRAND_pseudo_bytes()\fR puts \fBnum\fR pseudo-random bytes into \fBbuf\fR.
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150Pseudo-random byte sequences generated by \fIRAND_pseudo_bytes()\fR will be
151unique if they are of sufficient length, but are not necessarily
152unpredictable. They can be used for non-cryptographic purposes and for
153certain purposes in cryptographic protocols, but usually not for key
154generation etc.
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155.PP
156The contents of \fBbuf\fR is mixed into the entropy pool before retrieving
157the new pseudo-random bytes unless disabled at compile time (see \s-1FAQ\s0).
984263bc 158.SH "RETURN VALUES"
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159.IX Header "RETURN VALUES"
160\&\fIRAND_bytes()\fR returns 1 on success, 0 otherwise. The error code can be
161obtained by \fIERR_get_error\fR\|(3). \fIRAND_pseudo_bytes()\fR returns 1 if the
984263bc 162bytes generated are cryptographically strong, 0 otherwise. Both
8b0cefbb 163functions return \-1 if they are not supported by the current \s-1RAND\s0
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164method.
165.SH "SEE ALSO"
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166.IX Header "SEE ALSO"
167\&\fIrand\fR\|(3), \fIERR_get_error\fR\|(3),
168\&\fIRAND_add\fR\|(3)
984263bc 169.SH "HISTORY"
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170.IX Header "HISTORY"
171\&\fIRAND_bytes()\fR is available in all versions of SSLeay and OpenSSL. It
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172has a return value since OpenSSL 0.9.5. \fIRAND_pseudo_bytes()\fR was added
173in OpenSSL 0.9.5.