/
getbytesfromstring.xml
168 lines (156 loc) · 4.35 KB
/
getbytesfromstring.xml
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
<?xml version="1.0" encoding="utf-8"?>
<refentry xml:id="random-randomizer.getbytesfromstring" xmlns="http://docbook.org/ns/docbook" xmlns:xlink="http://www.w3.org/1999/xlink">
<refnamediv>
<refname>Random\Randomizer::getBytesFromString</refname>
<refpurpose>Get random bytes from a source string</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis role="Random\\Randomizer">
<modifier>public</modifier> <type>string</type><methodname>Random\Randomizer::getBytesFromString</methodname>
<methodparam><type>string</type><parameter>string</parameter></methodparam>
<methodparam><type>int</type><parameter>length</parameter></methodparam>
</methodsynopsis>
<para>
Generates a string containing uniformly selected random bytes from the
input <parameter>string</parameter> with the requested <parameter>length</parameter>.
</para>
<para>
The chance for a byte to be selected is proportional to its share
of the input <parameter>string</parameter>. If each byte occurs
the same amount of times, each byte is equally likely to be selected.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>string</parameter></term>
<listitem>
<para>
The &string; from which the returned bytes are selected.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>length</parameter></term>
<listitem>
<para>
The length of the random &string; that should be returned in bytes; must be <literal>1</literal> or greater.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
A &string; containing the requested number of random bytes taken from the input <parameter>string</parameter>.
</para>
</refsect1>
<refsect1 role="errors">
&reftitle.errors;
<itemizedlist>
<listitem>
<simpara>
If <parameter>string</parameter> is empty,
a <classname>ValueError</classname> will be thrown.
</simpara>
</listitem>
<listitem>
<simpara>
If the value of <parameter>length</parameter> is less than <literal>1</literal>,
a <classname>ValueError</classname> will be thrown.
</simpara>
</listitem>
&random.engineErrors;
</itemizedlist>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<example>
<title><methodname>Random\Randomizer::getBytesFromString</methodname> example</title>
<programlisting role="php">
<![CDATA[
<?php
$randomizer = new \Random\Randomizer();
printf(
"%s.example.com",
$randomizer->getBytesFromString('abcdefghijklmnopqrstuvwxyz0123456789', 16)
);
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
3zsw04eiubcf82jd.example.com
]]>
</screen>
</example>
<example>
<title>Generate a random code for multi-factor authentication</title>
<programlisting role="php">
<![CDATA[
<?php
// The Secure engine is the default, but we make it explicit, because
// multi-factor codes are security sensitive.
$randomizer = new \Random\Randomizer(new \Random\Engine\Secure());
echo implode('-', str_split($randomizer->getBytesFromString('0123456789', 20), 5));
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
11551-80418-27047-42075
]]>
</screen>
</example>
<example>
<title>Select from a string with a non-uniform distribution</title>
<programlisting role="php">
<![CDATA[
<?php
$randomizer = new \Random\Randomizer();
echo $randomizer->getBytesFromString('aaaaabcdef', 20);
?>
]]>
</programlisting>
&example.outputs.similar;
<screen>
<![CDATA[
fddacbeaaeaaacaaaaca
]]>
</screen>
</example>
</refsect1>
<refsect1 role="seealso">
&reftitle.seealso;
<simplelist>
<member><methodname>Random\Randomizer::getBytes</methodname></member>
</simplelist>
</refsect1>
</refentry>
<!--Keep this comment at the end of the file
Local variables:
mode: sgml
sgml-omittag:t
sgml-shorttag:t
sgml-minimize-attributes:nil
sgml-always-quote-attributes:t
sgml-indent-step:1
sgml-indent-data:t
indent-tabs-mode:nil
sgml-parent-document:nil
sgml-default-dtd-file:"~/.phpdoc/manual.ced"
sgml-exposed-tags:nil
sgml-local-catalogs:nil
sgml-local-ecat-files:nil
End:
vim600: syn=xml fen fdm=syntax fdl=2 si
vim: et tw=78 syn=sgml
vi: ts=1 sw=1
-->