php-doc-en/reference/csprng/functions/random-bytes.xml
2016-02-18 11:29:14 +00:00

111 lines
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XML

<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision$ -->
<refentry xml:id="function.random-bytes" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>random_bytes</refname>
<refpurpose>Generates cryptographically secure pseudo-random bytes</refpurpose>
</refnamediv>
<refsect1 role="description"><!-- {{{ -->
&reftitle.description;
<methodsynopsis role="procedural">
<type>string</type><methodname>random_bytes</methodname>
<methodparam><type>int</type><parameter>length</parameter></methodparam>
</methodsynopsis>
<para>
Generates an arbitrary length string of cryptographic random bytes that are
suitable for cryptographic use, such as when generating salts, keys or
initialization vectors.
</para>
&csprng.sources;
&csprng.function.backport;
</refsect1><!-- }}} -->
<refsect1 role="parameters"><!-- {{{ -->
&reftitle.parameters;
<variablelist>
<varlistentry>
<term><parameter>length</parameter></term>
<listitem>
<para>
The length of the random string that should be returned in bytes.
</para>
</listitem>
</varlistentry>
</variablelist>
</refsect1><!-- }}} -->
<refsect1 role="returnvalues"><!-- {{{ -->
&reftitle.returnvalues;
<para>
Returns a string containing the requested number of cryptographically
secure random bytes.
</para>
</refsect1><!-- }}} -->
<refsect1 role="errors"><!-- {{{ -->
&reftitle.errors;
<itemizedlist>
&csprng.errors;
<listitem>
<simpara>
If an invalid <parameter>length</parameter> of bytes is given, an
<classname>Error</classname> will be thrown.
</simpara>
</listitem>
</itemizedlist>
</refsect1><!-- }}} -->
<refsect1 role="examples"><!-- {{{ -->
&reftitle.examples;
<example xml:id="random-bytes.example.basic"><!-- {{{ -->
<title><function>random_bytes</function> example</title>
<programlisting role="php">
<![CDATA[
<?php
$bytes = random_bytes(5);
var_dump(bin2hex($bytes));
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
string(10) "385e33f741"
]]>
</screen>
</example><!-- }}} -->
</refsect1><!-- }}} -->
<refsect1 role="seealso"><!-- {{{ -->
&reftitle.seealso;
<simplelist>
<member><function>random_int</function></member>
<member><function>openssl_random_pseudo_bytes</function></member>
<member><function>bin2hex</function></member>
</simplelist>
</refsect1><!-- }}} -->
</refentry>
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