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https://github.com/sigmasternchen/php-doc-en
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074be37a4b
Patch by Marie Minasyan git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@333209 c90b9560-bf6c-de11-be94-00142212c4b1
142 lines
4 KiB
XML
142 lines
4 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<appendix xml:id="mcrypt.constants" xmlns="http://docbook.org/ns/docbook">
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&reftitle.constants;
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&extension.constants;
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<para>
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Mcrypt can operate in four block cipher modes (<literal>CBC</literal>,
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<literal>OFB</literal>, <literal>CFB</literal>, and
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<literal>ECB</literal>). If linked against libmcrypt-2.4.x or higher the
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functions can also operate in the block cipher mode <literal>nOFB</literal>
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and in <literal>STREAM</literal> mode. Below you find a list with all
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supported encryption modes together with the constants that are
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defined for the encryption mode. For a more complete reference and
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discussion see &book.applied.cryptography;.
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<itemizedlist>
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<listitem>
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<simpara>
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<constant>MCRYPT_MODE_ECB</constant> (<literal>electronic
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codebook</literal>) is suitable for random data,
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such as encrypting other keys. Since data there is short and random,
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the disadvantages of ECB have a favorable negative effect.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<constant>MCRYPT_MODE_CBC</constant> (<literal>cipher block
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chaining</literal>) is especially suitable for
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encrypting files where the security is increased over <literal>ECB</literal>
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significantly.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<constant>MCRYPT_MODE_CFB</constant> (<literal>cipher
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feedback</literal>) is the best mode for encrypting byte
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streams where single bytes must be encrypted.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<constant>MCRYPT_MODE_OFB</constant> (<literal>output feedback, in
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8bit</literal>) is comparable to <literal>CFB</literal>, but
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can be used in applications where error propagation cannot
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be tolerated. It's insecure (because it operates in 8bit
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mode) so it is not recommended to use it.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<constant>MCRYPT_MODE_NOFB</constant> (<literal>output feedback,
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in nbit</literal>) is comparable to OFB, but
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more secure because it operates on the block size of the algorithm.
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<constant>MCRYPT_MODE_STREAM</constant> is an extra mode to include
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some stream algorithms like <literal>"WAKE"</literal> or <literal>"RC4"</literal>.
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</simpara>
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</listitem>
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</itemizedlist>
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</para>
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<para>
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Some other mode and random device constants:
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<variablelist>
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<varlistentry xml:id="constant.mcrypt-encrypt">
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<term>
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<constant>MCRYPT_ENCRYPT</constant>
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(<type>integer</type>)
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</term>
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<listitem>
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<simpara>
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry xml:id="constant.mcrypt-decrypt">
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<term>
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<constant>MCRYPT_DECRYPT</constant>
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(<type>integer</type>)
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</term>
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<listitem>
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<simpara>
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry xml:id="constant.mcrypt-dev-random">
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<term>
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<constant>MCRYPT_DEV_RANDOM</constant>
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(<type>integer</type>)
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</term>
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<listitem>
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<simpara>
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry xml:id="constant.mcrypt-dev-urandom">
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<term>
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<constant>MCRYPT_DEV_URANDOM</constant>
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(<type>integer</type>)
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</term>
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<listitem>
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<simpara>
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</simpara>
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</listitem>
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</varlistentry>
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<varlistentry xml:id="constant.mcrypt-rand">
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<term>
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<constant>MCRYPT_RAND</constant>
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(<type>integer</type>)
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</term>
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<listitem>
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<simpara>
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</simpara>
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</listitem>
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</varlistentry>
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</variablelist>
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</para>
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</appendix>
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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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-->
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