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<?xml version="1.0" encoding="utf-8"?>
<!-- $Revision: 331335 $ -->
<refentry xml:id="function.mcrypt-encrypt" xmlns="http://docbook.org/ns/docbook">
<refnamediv>
<refname>mcrypt_encrypt</refname>
<refpurpose>Encrypts plaintext with given parameters</refpurpose>
</refnamediv>
<refsect1 role="description">
&reftitle.description;
<methodsynopsis>
<type>string</type><methodname>mcrypt_encrypt</methodname>
<methodparam><type>string</type><parameter>cipher</parameter></methodparam>
<methodparam><type>string</type><parameter>key</parameter></methodparam>
<methodparam><type>string</type><parameter>data</parameter></methodparam>
<methodparam><type>string</type><parameter>mode</parameter></methodparam>
<methodparam choice="opt"><type>string</type><parameter>iv</parameter></methodparam>
</methodsynopsis>
<para>
Encrypts the data and returns it.
</para>
</refsect1>
<refsect1 role="parameters">
&reftitle.parameters;
<para>
<variablelist>
<varlistentry>
<term><parameter>cipher</parameter></term>
<listitem>
&mcrypt.parameter.cipher;
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>key</parameter></term>
<listitem>
<para>
The key with which the data will be encrypted. If it's smaller than
the required keysize, it is padded with '<literal>\0</literal>'. It is
better not to use ASCII strings for keys.
</para>
<para>
It is recommended to use the mhash functions to create a key from a
string.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>data</parameter></term>
<listitem>
<para>
The data that will be encrypted with the given <parameter>cipher</parameter>
and <parameter>mode</parameter>. If the size of the data is not n * blocksize,
the data will be padded with '<literal>\0</literal>'.
</para>
<para>
The returned crypttext can be larger than the size of the data that was
given by <parameter>data</parameter>.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>mode</parameter></term>
<listitem>
&mcrypt.parameter.mode;
</listitem>
</varlistentry>
<varlistentry>
<term><parameter>iv</parameter></term>
<listitem>
&mcrypt.parameter.iv;
</listitem>
</varlistentry>
</variablelist>
</para>
</refsect1>
<refsect1 role="returnvalues">
&reftitle.returnvalues;
<para>
Returns the encrypted data, as a string.
</para>
</refsect1>
<refsect1 role="examples">
&reftitle.examples;
<para>
<example>
<title><function>mcrypt_encrypt</function> Example</title>
<programlisting role="php">
<![CDATA[
<?php
# --- ENCRYPTION ---
# the key should be random binary, use scrypt, bcrypt or PBKDF2 to
# convert a string into a key
# key is specified using hexadecimal
$key = pack('H*', "bcb04b7e103a0cd8b54763051cef08bc55abe029fdebae5e1d417e2ffb2a00a3");
# show key size use either 16, 24 or 32 byte keys for AES-128, 192
# and 256 respectively
$key_size = strlen($key);
echo "Key size: " . $key_size . "\n";
$plaintext = "This string was AES-256 / CBC / ZeroBytePadding encrypted.";
# create a random IV to use with CBC encoding
$iv_size = mcrypt_get_iv_size(MCRYPT_RIJNDAEL_128, MCRYPT_MODE_CBC);
$iv = mcrypt_create_iv($iv_size, MCRYPT_RAND);
# creates a cipher text compatible with AES (Rijndael block size = 128)
# to keep the text confidential
# only suitable for encoded input that never ends with value 00h
# (because of default zero padding)
$ciphertext = mcrypt_encrypt(MCRYPT_RIJNDAEL_128, $key,
$plaintext, MCRYPT_MODE_CBC, $iv);
# prepend the IV for it to be available for decryption
$ciphertext = $iv . $ciphertext;
# encode the resulting cipher text so it can be represented by a string
$ciphertext_base64 = base64_encode($ciphertext);
echo $ciphertext_base64 . "\n";
# === WARNING ===
# Resulting cipher text has no integrity or authenticity added
# and is not protected against padding oracle attacks.
# --- DECRYPTION ---
$ciphertext_dec = base64_decode($ciphertext_base64);
# retrieves the IV, iv_size should be created using mcrypt_get_iv_size()
$iv_dec = substr($ciphertext_dec, 0, $iv_size);
# retrieves the cipher text (everything except the $iv_size in the front)
$ciphertext_dec = substr($ciphertext_dec, $iv_size);
# may remove 00h valued characters from end of plain text
$plaintext_dec = mcrypt_decrypt(MCRYPT_RIJNDAEL_128, $key,
$ciphertext_dec, MCRYPT_MODE_CBC, $iv_dec);
echo $plaintext_dec . "\n";
?>
]]>
</programlisting>
&example.outputs;
<screen>
<![CDATA[
Key size: 32
ENJW8mS2KaJoNB5E5CoSAAu0xARgsR1bdzFWpEn+poYw45q+73az5kYi4j+0haevext1dGrcW8Qi59txfCBV8BBj3bzRP3dFCp3CPQSJ8eU=
This string was AES-256 / CBC / ZeroBytePadding encrypted.
]]>
</screen>
</example>
</para>
<para>
See also <function>mcrypt_module_open</function> for a more advanced API
and an example.
</para>
</refsect1>
</refentry>
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