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https://github.com/sigmasternchen/php-doc-en
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af4410a7e1
still using this, after discussion on the phpdoc list. From now on, manual.ced will need to be found at ~/.phpdoc/manual.ced. git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@288721 c90b9560-bf6c-de11-be94-00142212c4b1
123 lines
3.7 KiB
XML
123 lines
3.7 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.mcrypt-create-iv" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>mcrypt_create_iv</refname>
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<refpurpose>Create an initialization vector (IV) from a random source</refpurpose>
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</refnamediv>
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<refsect1 role="description">
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&reftitle.description;
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<methodsynopsis>
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<type>string</type><methodname>mcrypt_create_iv</methodname>
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<methodparam><type>int</type><parameter>size</parameter></methodparam>
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<methodparam choice="opt"><type>int</type><parameter>source</parameter><initializer>MCRYPT_DEV_RANDOM</initializer></methodparam>
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</methodsynopsis>
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<para>
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Create an initialization vector (IV) from a random source.
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</para>
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<para>
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The IV is only meant to give an alternative seed to the encryption
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routines. This IV does not need to be secret at all, though it can be
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desirable. You even can send it along with your ciphertext without
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losing security.
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</para>
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</refsect1>
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<refsect1 role="parameters">
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&reftitle.parameters;
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<para>
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<variablelist>
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<varlistentry>
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<term><parameter>size</parameter></term>
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<listitem>
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<para>
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Determines the size of the IV, parameter <parameter>source</parameter>
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(defaults to random value) specifies the source of the IV.
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</para>
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</listitem>
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</varlistentry>
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<varlistentry>
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<term><parameter>source</parameter></term>
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<listitem>
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<para>
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The source can be <constant>MCRYPT_RAND</constant> (system random
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number generator), <constant>MCRYPT_DEV_RANDOM</constant> (read
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data from <filename>/dev/random</filename>) and
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<constant>MCRYPT_DEV_URANDOM</constant> (read data from
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<filename>/dev/urandom</filename>). <constant>MCRYPT_RAND</constant>
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is the only one supported on Windows because Windows (of course)
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doesn't have <filename>/dev/random</filename> or
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<filename>/dev/urandom</filename>.
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</para>
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<note>
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<para>
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When using <constant>MCRYPT_RAND</constant>, remember to call
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<function>srand</function> before
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<function>mcrypt_create_iv</function> to initialize the random
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number generator; it is not seeded automatically like
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<function>rand</function> is.
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</para>
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</note>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</refsect1>
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<refsect1 role="returnvalues">
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&reftitle.returnvalues;
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<para>
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Returns the initialization vector, or &false; on error.
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</para>
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</refsect1>
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<refsect1 role="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>mcrypt_create_iv</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$size = mcrypt_get_iv_size(MCRYPT_CAST_256, MCRYPT_MODE_CFB);
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$iv = mcrypt_create_iv($size, MCRYPT_DEV_RANDOM);
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?>
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]]>
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</programlisting>
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</example>
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</para>
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</refsect1>
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<refsect1 role="seealso">
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&reftitle.seealso;
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<para>
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<simplelist>
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<member><link xlink:href="&url.mcrypt.iv;">&url.mcrypt.iv;</link></member>
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<member><link xlink:href="&url.mcrypt.bcm;">&url.mcrypt.bcm;</link></member>
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<member>Chapter 9.3 of Applied Cryptography by Schneier (ISBN 0-471-11709-9)</member>
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</simplelist>
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</para>
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</refsect1>
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</refentry>
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<!-- Keep this comment at the end of the file
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Local variables:
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mode: sgml
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sgml-omittag:t
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sgml-shorttag:t
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sgml-minimize-attributes:nil
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sgml-always-quote-attributes:t
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sgml-indent-step:1
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sgml-indent-data:t
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indent-tabs-mode:nil
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sgml-parent-document:nil
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sgml-default-dtd-file:"~/.phpdoc/manual.ced"
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sgml-exposed-tags:nil
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sgml-local-catalogs:nil
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sgml-local-ecat-files:nil
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End:
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vim600: syn=xml fen fdm=syntax fdl=2 si
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vim: et tw=78 syn=sgml
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vi: ts=1 sw=1
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-->
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