mirror of
https://github.com/sigmasternchen/php-doc-en
synced 2025-03-19 10:28:54 +00:00
baf0dab17e
newly documented functions git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@82020 c90b9560-bf6c-de11-be94-00142212c4b1
81 lines
2.6 KiB
XML
81 lines
2.6 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
|
|
<!-- $Revision: 1.4 $ -->
|
|
<!-- splitted from ./en/functions/mcrypt.xml, last change in rev 1.2 -->
|
|
<refentry id="function.mcrypt-create-iv">
|
|
<refnamediv>
|
|
<refname>mcrypt_create_iv</refname>
|
|
<refpurpose>
|
|
Create an initialization vector (IV) from a random source
|
|
</refpurpose>
|
|
</refnamediv>
|
|
<refsect1>
|
|
<title>Description</title>
|
|
<methodsynopsis>
|
|
<type>string</type><methodname>mcrypt_create_iv</methodname>
|
|
<methodparam><type>int</type><parameter>size</parameter></methodparam>
|
|
<methodparam><type>int</type><parameter>source</parameter></methodparam>
|
|
</methodsynopsis>
|
|
<para>
|
|
<function>mcrypt_create_iv</function> is used to create an IV.
|
|
</para>
|
|
<para>
|
|
<function>mcrypt_create_iv</function> takes two arguments,
|
|
<parameter>size</parameter> determines the size of the IV,
|
|
<parameter>source</parameter> specifies the source of the IV.
|
|
</para>
|
|
<para>
|
|
The source can be MCRYPT_RAND (system random number generator),
|
|
MCRYPT_DEV_RANDOM (read data from /dev/random) and
|
|
MCRYPT_DEV_URANDOM (read data from /dev/urandom). If you use
|
|
MCRYPT_RAND, make sure to call srand() before to initialize the
|
|
random number generator.
|
|
</para>
|
|
<para>
|
|
<example>
|
|
<title><function>mcrypt_create_iv</function> example</title>
|
|
<programlisting role="php">
|
|
<![CDATA[
|
|
<?php
|
|
$size = mcrypt_get_iv_size (MCRYPT_CAST_256, MCRYPT_MODE_CFB);
|
|
$iv = mcrypt_create_iv ($size, MCRYPT_DEV_RANDOM);
|
|
?>
|
|
]]>
|
|
</programlisting>
|
|
</example>
|
|
</para>
|
|
<para>
|
|
The IV is only meant to give an alternative seed to the encryption
|
|
routines. This IV does not need to be secret at all, though it can be
|
|
desirable. You even can send it along with your ciphertext without
|
|
loosing security.
|
|
</para>
|
|
<para>
|
|
More information can be found at <ulink
|
|
url="&url.mcrypt.iv;">&url.mcrypt.iv;</ulink>, <ulink
|
|
url="&url.mcrypt.bcm;">&url.mcrypt.bcm;</ulink> and in chapter 9.3 of
|
|
Applied Cryptography by Schneier (ISBN 0-471-11709-9) for a discussion of
|
|
this topic.
|
|
</para>
|
|
</refsect1>
|
|
</refentry>
|
|
|
|
<!-- Keep this comment at the end of the file
|
|
Local variables:
|
|
mode: sgml
|
|
sgml-omittag:t
|
|
sgml-shorttag:t
|
|
sgml-minimize-attributes:nil
|
|
sgml-always-quote-attributes:t
|
|
sgml-indent-step:1
|
|
sgml-indent-data:t
|
|
indent-tabs-mode:nil
|
|
sgml-parent-document:nil
|
|
sgml-default-dtd-file:"../../../../manual.ced"
|
|
sgml-exposed-tags:nil
|
|
sgml-local-catalogs:nil
|
|
sgml-local-ecat-files:nil
|
|
End:
|
|
vim600: syn=xml fen fdm=syntax fdl=2 si
|
|
vim: et tw=78 syn=sgml
|
|
vi: ts=1 sw=1
|
|
-->
|