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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@129076 c90b9560-bf6c-de11-be94-00142212c4b1
135 lines
3.4 KiB
XML
135 lines
3.4 KiB
XML
<?xml version="1.0" encoding="iso-8859-1"?>
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<!-- $Revision: 1.2 $ -->
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<section id="mcrypt.constants">
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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 (CBC, OFB, CFB, and
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ECB). If linked against libmcrypt-2.4.x or higher the functions can also operate
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in the block cipher mode nOFB and in STREAM mode. Below you find a list
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with all supported encryption modes together with the constants that are
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defines 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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MCRYPT_MODE_ECB (electronic codebook) 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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MCRYPT_MODE_CBC (cipher block chaining) is especially suitable for
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encrypting files where the security is increased over ECB
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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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MCRYPT_MODE_CFB (cipher feedback) 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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MCRYPT_MODE_OFB (output feedback, in 8bit) is comparable to CFB, 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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MCRYPT_MODE_NOFB (output feedback, in nbit) 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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MCRYPT_MODE_STREAM is an extra mode to include some stream algorithms
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like WAKE or RC4.
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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>
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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>
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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>
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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>
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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>
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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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</section>
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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:"../../../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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