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https://github.com/sigmasternchen/php-doc-en
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git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@297028 c90b9560-bf6c-de11-be94-00142212c4b1
139 lines
3.8 KiB
XML
139 lines
3.8 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision$ -->
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<refentry xml:id="function.mdecrypt-generic" xmlns="http://docbook.org/ns/docbook">
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<refnamediv>
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<refname>mdecrypt_generic</refname>
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<refpurpose>Decrypt data</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>mdecrypt_generic</methodname>
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<methodparam><type>resource</type><parameter>td</parameter></methodparam>
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<methodparam><type>string</type><parameter>data</parameter></methodparam>
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</methodsynopsis>
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<para>
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This function decrypts data. Note that the length of the returned string
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can in fact be longer then the unencrypted string, due to the padding of
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the data.
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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>td</parameter></term>
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<listitem>
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<para>
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An encryption descriptor returned by
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<function>mcrypt_module_open</function>
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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>data</parameter></term>
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<listitem>
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<para>
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Encrypted data.
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</para>
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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="examples">
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&reftitle.examples;
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<para>
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<example>
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<title><function>mdecrypt_generic</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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/* Data */
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$key = 'this is a very long key, even too long for the cipher';
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$plain_text = 'very important data';
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/* Open module, and create IV */
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$td = mcrypt_module_open('des', '', 'ecb', '');
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$key = substr($key, 0, mcrypt_enc_get_key_size($td));
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$iv_size = mcrypt_enc_get_iv_size($td);
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$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
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/* Initialize encryption handle */
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if (mcrypt_generic_init($td, $key, $iv) != -1) {
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/* Encrypt data */
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$c_t = mcrypt_generic($td, $plain_text);
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mcrypt_generic_deinit($td);
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/* Reinitialize buffers for decryption */
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mcrypt_generic_init($td, $key, $iv);
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$p_t = mdecrypt_generic($td, $c_t);
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/* Clean up */
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mcrypt_generic_deinit($td);
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mcrypt_module_close($td);
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}
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if (strncmp($p_t, $plain_text, strlen($plain_text)) == 0) {
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echo "ok\n";
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} else {
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echo "error\n";
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}
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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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<para>
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The above example shows how to check if the data before the encryption is
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the same as the data after the decryption. It is very important to
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reinitialize the encryption buffer with
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<function>mcrypt_generic_init</function> before you try to decrypt the
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data.
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</para>
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<para>
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The decryption handle should always be initialized with
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<function>mcrypt_generic_init</function> with a key and an IV before
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calling this function. Where the encryption is done, you should free the
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encryption buffers by calling <function>mcrypt_generic_deinit</function>.
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See <function>mcrypt_module_open</function> for an 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><function>mcrypt_generic</function></member>
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<member><function>mcrypt_generic_init</function></member>
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<member><function>mcrypt_generic_deinit</function></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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