doc/html/openssl-rand.html - platform/external/python/pyopenssl - Gitiles

 <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
 <html>
 <head>
 <title>3.2 rand -- An interface to the OpenSSL pseudo random number generator </title>
 <META NAME="description" CONTENT="3.2 rand -- An interface to the OpenSSL pseudo random number generator ">
 <META NAME="keywords" CONTENT="pyOpenSSL">
 <META NAME="resource-type" CONTENT="document">
 <META NAME="distribution" CONTENT="global">
 <link rel="STYLESHEET" href="pyOpenSSL.css">
 <LINK REL="next" href="openssl-ssl.html">
 <LINK REL="previous" href="openssl-crypto.html">
 <LINK REL="up" href="openssl.html">
 <LINK REL="next" href="openssl-ssl.html">
 </head>
 <body>
 <DIV CLASS="navigation">
 <table align="center" width="100%" cellpadding="0" cellspacing="2">
 <tr>
 <td><A href="revoked.html"><img src="previous.gif"
   border="0" height="32"
   alt="Previous Page" width="32"></A></td>
 <td><A href="openssl.html"><img src="up.gif"
   border="0" height="32"
   alt="Up One Level" width="32"></A></td>
 <td><A href="openssl-ssl.html"><img src="next.gif"
   border="0" height="32"
   alt="Next Page" width="32"></A></td>
 <td align="center" width="100%">Python OpenSSL Manual</td>
 <td><A href="contents.html"><img src="contents.gif"
   border="0" height="32"
   alt="Contents" width="32"></A></td>
 <td><img src="blank.gif"
   border="0" height="32"
   alt="" width="32"></td>
 <td><img src="blank.gif"
   border="0" height="32"
   alt="" width="32"></td>
 </tr></table>
 <b class="navlabel">Previous:</b> <a class="sectref" href="revoked.html">3.1.12 Revoked objects</A>
 <b class="navlabel">Up:</b> <a class="sectref" href="openssl.html">3 OpenSSL  </A>
 <b class="navlabel">Next:</b> <a class="sectref" href="openssl-ssl.html">3.3 SSL  </A>
 <br><hr>
 </DIV>
 <!--End of Navigation Panel-->

 <H2><A NAME="SECTION000420000000000000000">&nbsp;</A>
 <BR>
 3.2 <tt class="module">rand</tt> -- An interface to the OpenSSL pseudo random number generator
 </H2>

 <P>


 <P>
 This module handles the OpenSSL pseudo random number generator (PRNG) and
 declares the following:

 <P>
 <dl><dt><b><a name='l2h-117'><tt class='function'>add</tt></a></b>(<var>string, entropy</var>)
 <dd>
 Mix bytes from <var>string</var> into the PRNG state. The <var>entropy</var> argument is
 (the lower bound of) an estimate of how much randomness is contained in
 <var>string</var>, measured in bytes. For more information, see e.g. <a class="rfc" name="rfcref-2324"
 href="http://www.ietf.org/rfc/rfc1750.txt">RFC 1750</a>.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-118'><tt class='function'>bytes</tt></a></b>(<var>num_bytes</var>)
 <dd>
 Get some random bytes from the PRNG as a string.

 <P>
 This is a wrapper for the C function <tt class="function">RAND_bytes</tt>.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-119'><tt class='function'>cleanup</tt></a></b>()
 <dd>
 Erase the memory used by the PRNG.

 <P>
 This is a wrapper for the C function <tt class="function">RAND_cleanup</tt>.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-120'><tt class='function'>egd</tt></a></b>(<var>path</var><big>[</big><var>, bytes</var><big>]</big>)
 <dd>
 Query the Entropy Gathering Daemon<A NAME="tex2html2"
   HREF="#foot1227"><SUP>2</SUP></A> on socket <var>path</var> for <var>bytes</var>
 bytes of random data and and uses <tt class="function">add</tt> to seed the PRNG. The default
 value of <var>bytes</var> is 255.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-121'><tt class='function'>load_file</tt></a></b>(<var>path</var><big>[</big><var>, bytes</var><big>]</big>)
 <dd>
 Read <var>bytes</var> bytes (or all of it, if <var>bytes</var> is negative) of data from
 the file <var>path</var> to seed the PRNG. The default value of <var>bytes</var> is -1.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-122'><tt class='function'>screen</tt></a></b>()
 <dd>
 Add the current contents of the screen to the PRNG state.
 Availability: Windows.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-123'><tt class='function'>seed</tt></a></b>(<var>string</var>)
 <dd>
 This is equivalent to calling <tt class="function">add</tt> with <var>entropy</var> as the length
 of the string.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-124'><tt class='function'>status</tt></a></b>()
 <dd>
 Returns true if the PRNG has been seeded with enough data, and false otherwise.
 </dl>

 <P>
 <dl><dt><b><a name='l2h-125'><tt class='function'>write_file</tt></a></b>(<var>path</var>)
 <dd>
 Write a number of random bytes (currently 1024) to the file <var>path</var>. This
 file can then be used with <tt class="function">load_file</tt> to seed the PRNG again.
 </dl>

 <P>
 <dl><dt><b>exception <a name='l2h-126'><tt class='exception'>Error</tt></a></b>
 <dd>
 If the current RAND method supports any errors, this is raised when needed.
 The default method does not raise this when the entropy pool is depleted.

 <P>
 Whenever this exception is raised directly, it has a list of error messages
 from the OpenSSL error queue, where each item is a tuple <code>(<var>lib</var>,
 <var>function</var>, <var>reason</var>)</code>. Here <var>lib</var>, <var>function</var> and <var>reason</var>
 are all strings, describing where and what the problem is. See <span class='manpage'><i>err</i>(3)</span>
 for more information.
 </dl>

 <P>
 <BR><HR><H4>Footnotes</H4>
 <DL>
 <DT><A NAME="foot1227">... Daemon</A><A
  href="openssl-rand.html#tex2html2"><SUP>2</SUP></A></DT>
 <DD>See
 <a class="url" href="http://www.lothar.com/tech/crypto/">http://www.lothar.com/tech/crypto/</a>

 </DD>
 </DL>
 <DIV CLASS="navigation">
 <p><hr>
 <table align="center" width="100%" cellpadding="0" cellspacing="2">
 <tr>
 <td><A href="revoked.html"><img src="previous.gif"
   border="0" height="32"
   alt="Previous Page" width="32"></A></td>
 <td><A href="openssl.html"><img src="up.gif"
   border="0" height="32"
   alt="Up One Level" width="32"></A></td>
 <td><A href="openssl-ssl.html"><img src="next.gif"
   border="0" height="32"
   alt="Next Page" width="32"></A></td>
 <td align="center" width="100%">Python OpenSSL Manual</td>
 <td><A href="contents.html"><img src="contents.gif"
   border="0" height="32"
   alt="Contents" width="32"></A></td>
 <td><img src="blank.gif"
   border="0" height="32"
   alt="" width="32"></td>
 <td><img src="blank.gif"
   border="0" height="32"
   alt="" width="32"></td>
 </tr></table>
 <b class="navlabel">Previous:</b> <a class="sectref" href="revoked.html">3.1.12 Revoked objects</A>
 <b class="navlabel">Up:</b> <a class="sectref" href="openssl.html">3 OpenSSL  </A>
 <b class="navlabel">Next:</b> <a class="sectref" href="openssl-ssl.html">3.3 SSL  </A>
 <hr>
 <span class="release-info">Release 0.12.</span>
 </DIV>
 <!--End of Navigation Panel-->

 </BODY>
 </HTML>
	<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
	<html>
	<head>
	<title>3.2 rand -- An interface to the OpenSSL pseudo random number generator </title>
	<META NAME="description" CONTENT="3.2 rand -- An interface to the OpenSSL pseudo random number generator ">
	<META NAME="keywords" CONTENT="pyOpenSSL">
	<META NAME="resource-type" CONTENT="document">
	<META NAME="distribution" CONTENT="global">
	<link rel="STYLESHEET" href="pyOpenSSL.css">
	<LINK REL="next" href="openssl-ssl.html">
	<LINK REL="previous" href="openssl-crypto.html">
	<LINK REL="up" href="openssl.html">
	<LINK REL="next" href="openssl-ssl.html">
	</head>
	<body>
	<DIV CLASS="navigation">
	<table align="center" width="100%" cellpadding="0" cellspacing="2">
	<tr>
	<td><A href="revoked.html"><img src="previous.gif"
	border="0" height="32"
	alt="Previous Page" width="32"></A></td>
	<td><A href="openssl.html"><img src="up.gif"
	border="0" height="32"
	alt="Up One Level" width="32"></A></td>
	<td><A href="openssl-ssl.html"><img src="next.gif"
	border="0" height="32"
	alt="Next Page" width="32"></A></td>
	<td align="center" width="100%">Python OpenSSL Manual</td>
	<td><A href="contents.html"><img src="contents.gif"
	border="0" height="32"
	alt="Contents" width="32"></A></td>
	<td><img src="blank.gif"
	border="0" height="32"
	alt="" width="32"></td>
	<td><img src="blank.gif"
	border="0" height="32"
	alt="" width="32"></td>
	</tr></table>
	<b class="navlabel">Previous:</b> <a class="sectref" href="revoked.html">3.1.12 Revoked objects</A>
	<b class="navlabel">Up:</b> <a class="sectref" href="openssl.html">3 OpenSSL </A>
	<b class="navlabel">Next:</b> <a class="sectref" href="openssl-ssl.html">3.3 SSL </A>
	<br><hr>
	</DIV>
	<!--End of Navigation Panel-->

	<H2><A NAME="SECTION000420000000000000000"> </A>
	<BR>
	3.2 <tt class="module">rand</tt> -- An interface to the OpenSSL pseudo random number generator
	</H2>

	<P>


	<P>
	This module handles the OpenSSL pseudo random number generator (PRNG) and
	declares the following:

	<P>
	<dl><dt><b><a name='l2h-117'><tt class='function'>add</tt></a></b>(<var>string, entropy</var>)
	<dd>
	Mix bytes from <var>string</var> into the PRNG state. The <var>entropy</var> argument is
	(the lower bound of) an estimate of how much randomness is contained in
	<var>string</var>, measured in bytes. For more information, see e.g. <a class="rfc" name="rfcref-2324"
	href="http://www.ietf.org/rfc/rfc1750.txt">RFC 1750</a>.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-118'><tt class='function'>bytes</tt></a></b>(<var>num_bytes</var>)
	<dd>
	Get some random bytes from the PRNG as a string.

	<P>
	This is a wrapper for the C function <tt class="function">RAND_bytes</tt>.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-119'><tt class='function'>cleanup</tt></a></b>()
	<dd>
	Erase the memory used by the PRNG.

	<P>
	This is a wrapper for the C function <tt class="function">RAND_cleanup</tt>.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-120'><tt class='function'>egd</tt></a></b>(<var>path</var><big>[</big><var>, bytes</var><big>]</big>)
	<dd>
	Query the Entropy Gathering Daemon<A NAME="tex2html2"
	HREF="#foot1227"><SUP>2</SUP></A> on socket <var>path</var> for <var>bytes</var>
	bytes of random data and and uses <tt class="function">add</tt> to seed the PRNG. The default
	value of <var>bytes</var> is 255.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-121'><tt class='function'>load_file</tt></a></b>(<var>path</var><big>[</big><var>, bytes</var><big>]</big>)
	<dd>
	Read <var>bytes</var> bytes (or all of it, if <var>bytes</var> is negative) of data from
	the file <var>path</var> to seed the PRNG. The default value of <var>bytes</var> is -1.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-122'><tt class='function'>screen</tt></a></b>()
	<dd>
	Add the current contents of the screen to the PRNG state.
	Availability: Windows.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-123'><tt class='function'>seed</tt></a></b>(<var>string</var>)
	<dd>
	This is equivalent to calling <tt class="function">add</tt> with <var>entropy</var> as the length
	of the string.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-124'><tt class='function'>status</tt></a></b>()
	<dd>
	Returns true if the PRNG has been seeded with enough data, and false otherwise.
	</dl>

	<P>
	<dl><dt><b><a name='l2h-125'><tt class='function'>write_file</tt></a></b>(<var>path</var>)
	<dd>
	Write a number of random bytes (currently 1024) to the file <var>path</var>. This
	file can then be used with <tt class="function">load_file</tt> to seed the PRNG again.
	</dl>

	<P>
	<dl><dt><b>exception <a name='l2h-126'><tt class='exception'>Error</tt></a></b>
	<dd>
	If the current RAND method supports any errors, this is raised when needed.
	The default method does not raise this when the entropy pool is depleted.

	<P>
	Whenever this exception is raised directly, it has a list of error messages
	from the OpenSSL error queue, where each item is a tuple <code>(<var>lib</var>,
	<var>function</var>, <var>reason</var>)</code>. Here <var>lib</var>, <var>function</var> and <var>reason</var>
	are all strings, describing where and what the problem is. See <span class='manpage'><i>err</i>(3)</span>
	for more information.
	</dl>

	<P>
	<BR><HR><H4>Footnotes</H4>
	<DL>
	<DT><A NAME="foot1227">... Daemon</A><A
	href="openssl-rand.html#tex2html2"><SUP>2</SUP></A></DT>
	<DD>See
	<a class="url" href="http://www.lothar.com/tech/crypto/">http://www.lothar.com/tech/crypto/</a>

	</DD>
	</DL>
	<DIV CLASS="navigation">
	<p><hr>
	<table align="center" width="100%" cellpadding="0" cellspacing="2">
	<tr>
	<td><A href="revoked.html"><img src="previous.gif"
	border="0" height="32"
	alt="Previous Page" width="32"></A></td>
	<td><A href="openssl.html"><img src="up.gif"
	border="0" height="32"
	alt="Up One Level" width="32"></A></td>
	<td><A href="openssl-ssl.html"><img src="next.gif"
	border="0" height="32"
	alt="Next Page" width="32"></A></td>
	<td align="center" width="100%">Python OpenSSL Manual</td>
	<td><A href="contents.html"><img src="contents.gif"
	border="0" height="32"
	alt="Contents" width="32"></A></td>
	<td><img src="blank.gif"
	border="0" height="32"
	alt="" width="32"></td>
	<td><img src="blank.gif"
	border="0" height="32"
	alt="" width="32"></td>
	</tr></table>
	<b class="navlabel">Previous:</b> <a class="sectref" href="revoked.html">3.1.12 Revoked objects</A>
	<b class="navlabel">Up:</b> <a class="sectref" href="openssl.html">3 OpenSSL </A>
	<b class="navlabel">Next:</b> <a class="sectref" href="openssl-ssl.html">3.3 SSL </A>
	<hr>
	<span class="release-info">Release 0.12.</span>
	</DIV>
	<!--End of Navigation Panel-->

	</BODY>
	</HTML>