139 lines
4.1 KiB
HTML
139 lines
4.1 KiB
HTML
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
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<HTML><HEAD><TITLE>Man page of RAND</TITLE>
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</HEAD><BODY>
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<H1>RAND</H1>
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Section: OpenSSL (1SSL)<BR>Updated: 2021-03-22<BR><A HREF="#index">Index</A>
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<A HREF="/cgi-bin/man/man2html">Return to Main Contents</A><HR>
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<A NAME="lbAB"> </A>
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<H2>NAME</H2>
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openssl-rand, rand - generate pseudo-random bytes
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<A NAME="lbAC"> </A>
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<H2>SYNOPSIS</H2>
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<B>openssl rand</B>
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[<B>-help</B>]
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[<B>-out</B> <I>file</I>]
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[<B>-rand file...</B>]
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[<B>-writerand file</B>]
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[<B>-base64</B>]
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[<B>-hex</B>]
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<I>num</I>
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<A NAME="lbAD"> </A>
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<H2>DESCRIPTION</H2>
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This command generates <I>num</I> random bytes using a cryptographically
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secure pseudo random number generator (<FONT SIZE="-1">CSPRNG</FONT>).
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<P>
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The random bytes are generated using the <B><A HREF="/cgi-bin/man/man2html?3+RAND_bytes">RAND_bytes</A></B>(3) function,
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which provides a security level of 256 bits, provided it managed to
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seed itself successfully from a trusted operating system entropy source.
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Otherwise, the command will fail with a nonzero error code.
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For more details, see <B><A HREF="/cgi-bin/man/man2html?3+RAND_bytes">RAND_bytes</A></B>(3), <FONT SIZE="-1"><B><A HREF="/cgi-bin/man/man2html?7+RAND">RAND</A></B></FONT><B></B>(7), and <FONT SIZE="-1"><B><A HREF="/cgi-bin/man/man2html?7+RAND_DRBG">RAND_DRBG</A></B></FONT><B></B>(7).
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<A NAME="lbAE"> </A>
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<H2>OPTIONS</H2>
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<DL COMPACT>
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<DT id="1"><B>-help</B><DD>
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Print out a usage message.
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<DT id="2"><B>-out file</B><DD>
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Write to <I>file</I> instead of standard output.
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<DT id="3"><B>-rand file...</B><DD>
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A file or files containing random data used to seed the random number
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generator.
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Multiple files can be specified separated by an OS-dependent character.
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The separator is <B>;</B> for MS-Windows, <B>,</B> for OpenVMS, and <B>:</B> for
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all others.
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Explicitly specifying a seed file is in general not necessary, see the
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``<FONT SIZE="-1">NOTES''</FONT> section for more information.
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<DT id="4">[<B>-writerand file</B>]<DD>
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Writes random data to the specified <I>file</I> upon exit.
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This can be used with a subsequent <B>-rand</B> flag.
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<DT id="5"><B>-base64</B><DD>
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Perform base64 encoding on the output.
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<DT id="6"><B>-hex</B><DD>
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Show the output as a hex string.
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</DL>
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<A NAME="lbAF"> </A>
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<H2>NOTES</H2>
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Prior to OpenSSL 1.1.1, it was common for applications to store information
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about the state of the random-number generator in a file that was loaded
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at startup and rewritten upon exit. On modern operating systems, this is
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generally no longer necessary as OpenSSL will seed itself from a trusted
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entropy source provided by the operating system. The <B>-rand</B> and
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<B>-writerand</B> flags are still supported for special platforms or
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circumstances that might require them.
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<P>
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It is generally an error to use the same seed file more than once and
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every use of <B>-rand</B> should be paired with <B>-writerand</B>.
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<A NAME="lbAG"> </A>
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<H2>SEE ALSO</H2>
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<B><A HREF="/cgi-bin/man/man2html?3+RAND_bytes">RAND_bytes</A></B>(3),
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<FONT SIZE="-1"><B><A HREF="/cgi-bin/man/man2html?7+RAND">RAND</A></B></FONT><B></B>(7),
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<FONT SIZE="-1"><B><A HREF="/cgi-bin/man/man2html?7+RAND_DRBG">RAND_DRBG</A></B></FONT><B></B>(7)
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<A NAME="lbAH"> </A>
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<H2>COPYRIGHT</H2>
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Copyright 2000-2020 The OpenSSL Project Authors. All Rights Reserved.
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<P>
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Licensed under the OpenSSL license (the ``License''). You may not use
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this file except in compliance with the License. You can obtain a copy
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in the file <FONT SIZE="-1">LICENSE</FONT> in the source distribution or at
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<<A HREF="https://www.openssl.org/source/license.html">https://www.openssl.org/source/license.html</A>>.
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<P>
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<HR>
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<A NAME="index"> </A><H2>Index</H2>
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<DL>
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<DT id="7"><A HREF="#lbAB">NAME</A><DD>
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<DT id="8"><A HREF="#lbAC">SYNOPSIS</A><DD>
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<DT id="9"><A HREF="#lbAD">DESCRIPTION</A><DD>
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<DT id="10"><A HREF="#lbAE">OPTIONS</A><DD>
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<DT id="11"><A HREF="#lbAF">NOTES</A><DD>
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<DT id="12"><A HREF="#lbAG">SEE ALSO</A><DD>
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<DT id="13"><A HREF="#lbAH">COPYRIGHT</A><DD>
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</DL>
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<HR>
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This document was created by
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<A HREF="/cgi-bin/man/man2html">man2html</A>,
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using the manual pages.<BR>
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Time: 00:05:26 GMT, March 31, 2021
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</BODY>
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</HTML>
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