mirror of
https://github.com/sigmasternchen/php-doc-en
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b9271c0d58
git-svn-id: https://svn.php.net/repository/phpdoc/en/trunk@336957 c90b9560-bf6c-de11-be94-00142212c4b1
126 lines
3.3 KiB
XML
126 lines
3.3 KiB
XML
<?xml version="1.0" encoding="utf-8"?>
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<!-- $Revision: 299488 $ -->
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<refentry xml:id="function.random-bytes" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
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<refnamediv>
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<refname>random_bytes</refname>
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<refpurpose>Generates cryptographically secure pseudo-random bytes</refpurpose>
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</refnamediv>
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<refsect1 role="description"><!-- {{{ -->
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&reftitle.description;
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<methodsynopsis role="procedural">
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<type>string</type><methodname>random_bytes</methodname>
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<methodparam><type>int</type><parameter>length</parameter></methodparam>
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</methodsynopsis>
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<para>
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Generates an arbitrary length string of cryptographic random bytes that are suitable for use in cryptography when
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generating salts, keys and initialization vectors.
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</para>
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<para>
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The sources of random are as follows:
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</para>
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<itemizedlist>
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<listitem>
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<simpara>
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On Windows <function>CryptGenRandom</function> is used exclusively
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<function>arc4random_buf</function> is used if it is available (generally BSD specific)
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<filename>/dev/arandom</filename> is used where available
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</simpara>
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</listitem>
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<listitem>
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<simpara>
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<filename>/dev/urandom</filename> is used where none of the above is available
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</simpara>
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</listitem>
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</itemizedlist>
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</refsect1><!-- }}} -->
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<refsect1 role="parameters"><!-- {{{ -->
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&reftitle.parameters;
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<variablelist>
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<varlistentry>
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<term><parameter>length</parameter></term>
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<listitem>
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<para>
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The length of the random string that should be returned in bytes.
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</para>
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</listitem>
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</varlistentry>
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</variablelist>
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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 a string containing the crypto-secure random bytes in binary format.
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</para>
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</refsect1><!-- }}} -->
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<refsect1 role="errors"><!-- {{{ -->
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&reftitle.errors;
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<para>
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Issues an <constant>E_WARNING</constant> and returns &false; when a sufficient source of randomness is unavailable.
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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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<example xml:id="random-bytes.example.basic"><!-- {{{ -->
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<title><function>random-bytes</function> example</title>
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<programlisting role="php">
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<![CDATA[
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<?php
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$bytes = random_bytes(5);
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var_dump(bin2hex($bytes));
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?>
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]]>
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</programlisting>
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&example.outputs.similar;
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<screen>
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<![CDATA[
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string(10) "385e33f741"
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]]>
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</screen>
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</example><!-- }}} -->
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</refsect1><!-- }}} -->
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<refsect1 role="seealso"><!-- {{{ -->
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&reftitle.seealso;
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<simplelist>
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<member><function>random_int</function></member>
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<member><function>openssl_random_pseudo_bytes</function></member>
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<member><function>bin2hex</function></member>
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</simplelist>
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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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