<?php
/* vim: set expandtab tabstop=4 shiftwidth=4 softtabstop=4: */
/**
* Pure-PHP implementation of Rijndael.
*
* Does not use mcrypt, even when available, for reasons that are explained below.
*
* PHP versions 4 and 5
*
* If {@link Crypt_Rijndael::setBlockLength() setBlockLength()} isn't called, it'll be assumed to be 128 bits. If
* {@link Crypt_Rijndael::setKeyLength() setKeyLength()} isn't called, it'll be calculated from
* {@link Crypt_Rijndael::setKey() setKey()}. ie. if the key is 128-bits, the key length will be 128-bits. If it's
* 136-bits it'll be null-padded to 160-bits and 160 bits will be the key length until
* {@link Crypt_Rijndael::setKey() setKey()} is called, again, at which point, it'll be recalculated.
*
* Not all Rijndael implementations may support 160-bits or 224-bits as the block length / key length. mcrypt, for example,
* does not. AES, itself, only supports block lengths of 128 and key lengths of 128, 192, and 256.
* {@link http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=10 Rijndael-ammended.pdf#page=10} defines the
* algorithm for block lengths of 192 and 256 but not for block lengths / key lengths of 160 and 224. Indeed, 160 and 224
* are first defined as valid key / block lengths in
* {@link http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=44 Rijndael-ammended.pdf#page=44}:
* Extensions: Other block and Cipher Key lengths.
*
* {@internal The variable names are the same as those in
* {@link http://www.csrc.nist.gov/publications/fips/fips197/fips-197.pdf#page=10 fips-197.pdf#page=10}.}}
*
* Here's a short example of how to use this library:
* <code>
* <?php
* include('Crypt/Rijndael.php');
*
* $rijndael = new Crypt_Rijndael();
*
* $rijndael->setKey('abcdefghijklmnop');
*
* $size = 10 * 1024;
* $plaintext = '';
* for ($i = 0; $i < $size; $i++) {
* $plaintext.= 'a';
* }
*
* echo $rijndael->decrypt($rijndael->encrypt($plaintext));
* ?>
* </code>
*
* LICENSE: This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston,
* MA 02111-1307 USA
*
* @category Crypt
* @package Crypt_Rijndael
* @author Jim Wigginton <terrafrost@php.net>
* @copyright MMVIII Jim Wigginton
* @license http://www.gnu.org/licenses/lgpl.txt
* @version $Id: Rijndael.php,v 1.12 2010/02/09 06:10:26 terrafrost Exp $
* @link http://phpseclib.sourceforge.net
*/
/**#@+
* @access public
* @see Crypt_Rijndael::encrypt()
* @see Crypt_Rijndael::decrypt()
*/
/**
* Encrypt / decrypt using the Counter mode.
*
* Set to -1 since that's what Crypt/Random.php uses to index the CTR mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Counter_.28CTR.29
*/
define('CRYPT_RIJNDAEL_MODE_CTR', -1);
/**
* Encrypt / decrypt using the Electronic Code Book mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Electronic_codebook_.28ECB.29
*/
define('CRYPT_RIJNDAEL_MODE_ECB', 1);
/**
* Encrypt / decrypt using the Code Book Chaining mode.
*
* @link http://en.wikipedia.org/wiki/Block_cipher_modes_of_operation#Cipher-block_chaining_.28CBC.29
*/
define('CRYPT_RIJNDAEL_MODE_CBC', 2);
/**#@-*/
/**#@+
* @access private
* @see Crypt_Rijndael::Crypt_Rijndael()
*/
/**
* Toggles the internal implementation
*/
define('CRYPT_RIJNDAEL_MODE_INTERNAL', 1);
/**
* Toggles the mcrypt implementation
*/
define('CRYPT_RIJNDAEL_MODE_MCRYPT', 2);
/**#@-*/
/**
* Pure-PHP implementation of Rijndael.
*
* @author Jim Wigginton <terrafrost@php.net>
* @version 0.1.0
* @access public
* @package Crypt_Rijndael
*/
class Crypt_Rijndael {
/**
* The Encryption Mode
*
* @see Crypt_Rijndael::Crypt_Rijndael()
* @var Integer
* @access private
*/
var $mode;
/**
* The Key
*
* @see Crypt_Rijndael::setKey()
* @var String
* @access private
*/
var $key = "\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0\0";
/**
* The Initialization Vector
*
* @see Crypt_Rijndael::setIV()
* @var String
* @access private
*/
var $iv = '';
/**
* A "sliding" Initialization Vector
*
* @see Crypt_Rijndael::enableContinuousBuffer()
* @var String
* @access private
*/
var $encryptIV = '';
/**
* A "sliding" Initialization Vector
*
* @see Crypt_Rijndael::enableContinuousBuffer()
* @var String
* @access private
*/
var $decryptIV = '';
/**
* Continuous Buffer status
*
* @see Crypt_Rijndael::enableContinuousBuffer()
* @var Boolean
* @access private
*/
var $continuousBuffer = false;
/**
* Padding status
*
* @see Crypt_Rijndael::enablePadding()
* @var Boolean
* @access private
*/
var $padding = true;
/**
* Does the key schedule need to be (re)calculated?
*
* @see setKey()
* @see setBlockLength()
* @see setKeyLength()
* @var Boolean
* @access private
*/
var $changed = true;
/**
* Has the key length explicitly been set or should it be derived from the key, itself?
*
* @see setKeyLength()
* @var Boolean
* @access private
*/
var $explicit_key_length = false;
/**
* The Key Schedule
*
* @see _setup()
* @var Array
* @access private
*/
var $w;
/**
* The Inverse Key Schedule
*
* @see _setup()
* @var Array
* @access private
*/
var $dw;
/**
* The Block Length
*
* @see setBlockLength()
* @var Integer
* @access private
* @internal The max value is 32, the min value is 16. All valid values are multiples of 4. Exists in conjunction with
* $Nb because we need this value and not $Nb to pad strings appropriately.
*/
var $block_size = 16;
/**
* The Block Length divided by 32
*
* @see setBlockLength()
* @var Integer
* @access private
* @internal The max value is 256 / 32 = 8, the min value is 128 / 32 = 4. Exists in conjunction with $block_size
* because the encryption / decryption / key schedule creation requires this number and not $block_size. We could
* derive this from $block_size or vice versa, but that'd mean we'd have to do multiple shift operations, so in lieu
* of that, we'll just precompute it once.
*
*/
var $Nb = 4;
/**
* The Key Length
*
* @see setKeyLength()
* @var Integer
* @access private
* @internal The max value is 256 / 8 = 32, the min value is 128 / 8 = 16. Exists in conjunction with $key_size
* because the encryption / decryption / key schedule creation requires this number and not $key_size. We could
* derive this from $key_size or vice versa, but that'd mean we'd have to do multiple shift operations, so in lieu
* of that, we'll just precompute it once.
*/
var $key_size = 16;
/**
* The Key Length divided by 32
*
* @see setKeyLength()
* @var Integer
* @access private
* @internal The max value is 256 / 32 = 8, the min value is 128 / 32 = 4
*/
var $Nk = 4;
/**
* The Number of Rounds
*
* @var Integer
* @access private
* @internal The max value is 14, the min value is 10.
*/
var $Nr;
/**
* Shift offsets
*
* @var Array
* @access private
*/
var $c;
/**
* Precomputed mixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $t0;
/**
* Precomputed mixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $t1;
/**
* Precomputed mixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $t2;
/**
* Precomputed mixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $t3;
/**
* Precomputed invMixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $dt0;
/**
* Precomputed invMixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $dt1;
/**
* Precomputed invMixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $dt2;
/**
* Precomputed invMixColumns table
*
* @see Crypt_Rijndael()
* @var Array
* @access private
*/
var $dt3;
/**
* Default Constructor.
*
* Determines whether or not the mcrypt extension should be used. $mode should only, at present, be
* CRYPT_RIJNDAEL_MODE_ECB or CRYPT_RIJNDAEL_MODE_CBC. If not explictly set, CRYPT_RIJNDAEL_MODE_CBC will be used.
*
* @param optional Integer $mode
* @return Crypt_Rijndael
* @access public
*/
function Crypt_Rijndael($mode = CRYPT_RIJNDAEL_MODE_CBC)
{
switch ($mode) {
case CRYPT_RIJNDAEL_MODE_ECB:
case CRYPT_RIJNDAEL_MODE_CBC:
case CRYPT_RIJNDAEL_MODE_CTR:
$this->mode = $mode;
break;
default:
$this->mode = CRYPT_RIJNDAEL_MODE_CBC;
}
$t3 = &$this->t3;
$t2 = &$this->t2;
$t1 = &$this->t1;
$t0 = &$this->t0;
$dt3 = &$this->dt3;
$dt2 = &$this->dt2;
$dt1 = &$this->dt1;
$dt0 = &$this->dt0;
// according to <http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=19> (section 5.2.1),
// precomputed tables can be used in the mixColumns phase. in that example, they're assigned t0...t3, so
// those are the names we'll use.
$t3 = array(
0x6363A5C6, 0x7C7C84F8, 0x777799EE, 0x7B7B8DF6, 0xF2F20DFF, 0x6B6BBDD6, 0x6F6FB1DE, 0xC5C55491,
0x30305060, 0x01010302, 0x6767A9CE, 0x2B2B7D56, 0xFEFE19E7, 0xD7D762B5, 0xABABE64D, 0x76769AEC,
0xCACA458F, 0x82829D1F, 0xC9C94089, 0x7D7D87FA, 0xFAFA15EF, 0x5959EBB2, 0x4747C98E, 0xF0F00BFB,
0xADADEC41, 0xD4D467B3, 0xA2A2FD5F, 0xAFAFEA45, 0x9C9CBF23, 0xA4A4F753, 0x727296E4, 0xC0C05B9B,
0xB7B7C275, 0xFDFD1CE1, 0x9393AE3D, 0x26266A4C, 0x36365A6C, 0x3F3F417E, 0xF7F702F5, 0xCCCC4F83,
0x34345C68, 0xA5A5F451, 0xE5E534D1, 0xF1F108F9, 0x717193E2, 0xD8D873AB, 0x31315362, 0x15153F2A,
0x04040C08, 0xC7C75295, 0x23236546, 0xC3C35E9D, 0x18182830, 0x9696A137, 0x05050F0A, 0x9A9AB52F,
0x0707090E, 0x12123624, 0x80809B1B, 0xE2E23DDF, 0xEBEB26CD, 0x2727694E, 0xB2B2CD7F, 0x75759FEA,
0x09091B12, 0x83839E1D, 0x2C2C7458, 0x1A1A2E34, 0x1B1B2D36, 0x6E6EB2DC, 0x5A5AEEB4, 0xA0A0FB5B,
0x5252F6A4, 0x3B3B4D76, 0xD6D661B7, 0xB3B3CE7D, 0x29297B52, 0xE3E33EDD, 0x2F2F715E, 0x84849713,
0x5353F5A6, 0xD1D168B9, 0x00000000, 0xEDED2CC1, 0x20206040, 0xFCFC1FE3, 0xB1B1C879, 0x5B5BEDB6,
0x6A6ABED4, 0xCBCB468D, 0xBEBED967, 0x39394B72, 0x4A4ADE94, 0x4C4CD498, 0x5858E8B0, 0xCFCF4A85,
0xD0D06BBB, 0xEFEF2AC5, 0xAAAAE54F, 0xFBFB16ED, 0x4343C586, 0x4D4DD79A, 0x33335566, 0x85859411,
0x4545CF8A, 0xF9F910E9, 0x02020604, 0x7F7F81FE, 0x5050F0A0, 0x3C3C4478, 0x9F9FBA25, 0xA8A8E34B,
0x5151F3A2, 0xA3A3FE5D, 0x4040C080, 0x8F8F8A05, 0x9292AD3F, 0x9D9DBC21, 0x38384870, 0xF5F504F1,
0xBCBCDF63, 0xB6B6C177, 0xDADA75AF, 0x21216342, 0x10103020, 0xFFFF1AE5, 0xF3F30EFD, 0xD2D26DBF,
0xCDCD4C81, 0x0C0C1418, 0x13133526, 0xECEC2FC3, 0x5F5FE1BE, 0x9797A235, 0x4444CC88, 0x1717392E,
0xC4C45793, 0xA7A7F255, 0x7E7E82FC, 0x3D3D477A, 0x6464ACC8, 0x5D5DE7BA, 0x19192B32, 0x737395E6,
0x6060A0C0, 0x81819819, 0x4F4FD19E, 0xDCDC7FA3, 0x22226644, 0x2A2A7E54, 0x9090AB3B, 0x8888830B,
0x4646CA8C, 0xEEEE29C7, 0xB8B8D36B, 0x14143C28, 0xDEDE79A7, 0x5E5EE2BC, 0x0B0B1D16, 0xDBDB76AD,
0xE0E03BDB, 0x32325664, 0x3A3A4E74, 0x0A0A1E14, 0x4949DB92, 0x06060A0C, 0x24246C48, 0x5C5CE4B8,
0xC2C25D9F, 0xD3D36EBD, 0xACACEF43, 0x6262A6C4, 0x9191A839, 0x9595A431, 0xE4E437D3, 0x79798BF2,
0xE7E732D5, 0xC8C8438B, 0x3737596E, 0x6D6DB7DA, 0x8D8D8C01, 0xD5D564B1, 0x4E4ED29C, 0xA9A9E049,
0x6C6CB4D8, 0x5656FAAC, 0xF4F407F3, 0xEAEA25CF, 0x6565AFCA, 0x7A7A8EF4, 0xAEAEE947, 0x08081810,
0xBABAD56F, 0x787888F0, 0x25256F4A, 0x2E2E725C, 0x1C1C2438, 0xA6A6F157, 0xB4B4C773, 0xC6C65197,
0xE8E823CB, 0xDDDD7CA1, 0x74749CE8, 0x1F1F213E, 0x4B4BDD96, 0xBDBDDC61, 0x8B8B860D, 0x8A8A850F,
0x707090E0, 0x3E3E427C, 0xB5B5C471, 0x6666AACC, 0x4848D890, 0x03030506, 0xF6F601F7, 0x0E0E121C,
0x6161A3C2, 0x35355F6A, 0x5757F9AE, 0xB9B9D069, 0x86869117, 0xC1C15899, 0x1D1D273A, 0x9E9EB927,
0xE1E138D9, 0xF8F813EB, 0x9898B32B, 0x11113322, 0x6969BBD2, 0xD9D970A9, 0x8E8E8907, 0x9494A733,
0x9B9BB62D, 0x1E1E223C, 0x87879215, 0xE9E920C9, 0xCECE4987, 0x5555FFAA, 0x28287850, 0xDFDF7AA5,
0x8C8C8F03, 0xA1A1F859, 0x89898009, 0x0D0D171A, 0xBFBFDA65, 0xE6E631D7, 0x4242C684, 0x6868B8D0,
0x4141C382, 0x9999B029, 0x2D2D775A, 0x0F0F111E, 0xB0B0CB7B, 0x5454FCA8, 0xBBBBD66D, 0x16163A2C
);
$dt3 = array(
0xF4A75051, 0x4165537E, 0x17A4C31A, 0x275E963A, 0xAB6BCB3B, 0x9D45F11F, 0xFA58ABAC, 0xE303934B,
0x30FA5520, 0x766DF6AD, 0xCC769188, 0x024C25F5, 0xE5D7FC4F, 0x2ACBD7C5, 0x35448026, 0x62A38FB5,
0xB15A49DE, 0xBA1B6725, 0xEA0E9845, 0xFEC0E15D, 0x2F7502C3, 0x4CF01281, 0x4697A38D, 0xD3F9C66B,
0x8F5FE703, 0x929C9515, 0x6D7AEBBF, 0x5259DA95, 0xBE832DD4, 0x7421D358, 0xE0692949, 0xC9C8448E,
0xC2896A75, 0x8E7978F4, 0x583E6B99, 0xB971DD27, 0xE14FB6BE, 0x88AD17F0, 0x20AC66C9, 0xCE3AB47D,
0xDF4A1863, 0x1A3182E5, 0x51336097, 0x537F4562, 0x6477E0B1, 0x6BAE84BB, 0x81A01CFE, 0x082B94F9,
0x48685870, 0x45FD198F, 0xDE6C8794, 0x7BF8B752, 0x73D323AB, 0x4B02E272, 0x1F8F57E3, 0x55AB2A66,
0xEB2807B2, 0xB5C2032F, 0xC57B9A86, 0x3708A5D3, 0x2887F230, 0xBFA5B223, 0x036ABA02, 0x16825CED,
0xCF1C2B8A, 0x79B492A7, 0x07F2F0F3, 0x69E2A14E, 0xDAF4CD65, 0x05BED506, 0x34621FD1, 0xA6FE8AC4,
0x2E539D34, 0xF355A0A2, 0x8AE13205, 0xF6EB75A4, 0x83EC390B, 0x60EFAA40, 0x719F065E, 0x6E1051BD,
0x218AF93E, 0xDD063D96, 0x3E05AEDD, 0xE6BD464D, 0x548DB591, 0xC45D0571, 0x06D46F04, 0x5015FF60,
0x98FB2419, 0xBDE997D6, 0x4043CC89, 0xD99E7767, 0xE842BDB0, 0x898B8807, 0x195B38E7, 0xC8EEDB79,
0x7C0A47A1, 0x420FE97C, 0x841EC9F8, 0x00000000, 0x80868309, 0x2BED4832, 0x1170AC1E, 0x5A724E6C,
0x0EFFFBFD, 0x8538560F, 0xAED51E3D, 0x2D392736, 0x0FD9640A, 0x5CA62168, 0x5B54D19B, 0x362E3A24,
0x0A67B10C, 0x57E70F93, 0xEE96D2B4, 0x9B919E1B, 0xC0C54F80, 0xDC20A261, 0x774B695A, 0x121A161C,
0x93BA0AE2, 0xA02AE5C0, 0x22E0433C, 0x1B171D12, 0x090D0B0E, 0x8BC7ADF2, 0xB6A8B92D, 0x1EA9C814,
0xF1198557, 0x75074CAF, 0x99DDBBEE, 0x7F60FDA3, 0x01269FF7, 0x72F5BC5C, 0x663BC544, 0xFB7E345B,
0x4329768B, 0x23C6DCCB, 0xEDFC68B6, 0xE4F163B8, 0x31DCCAD7, 0x63851042, 0x97224013, 0xC6112084,
0x4A247D85, 0xBB3DF8D2, 0xF93211AE, 0x29A16DC7, 0x9E2F4B1D, 0xB230F3DC, 0x8652EC0D, 0xC1E3D077,
0xB3166C2B, 0x70B999A9, 0x9448FA11, 0xE9642247, 0xFC8CC4A8, 0xF03F1AA0, 0x7D2CD856, 0x3390EF22,
0x494EC787, 0x38D1C1D9, 0xCAA2FE8C, 0xD40B3698, 0xF581CFA6, 0x7ADE28A5, 0xB78E26DA, 0xADBFA43F,
0x3A9DE42C, 0x78920D50, 0x5FCC9B6A, 0x7E466254, 0x8D13C2F6, 0xD8B8E890, 0x39F75E2E, 0xC3AFF582,
0x5D80BE9F, 0xD0937C69, 0xD52DA96F, 0x2512B3CF, 0xAC993BC8, 0x187DA710, 0x9C636EE8, 0x3BBB7BDB,
0x267809CD, 0x5918F46E, 0x9AB701EC, 0x4F9AA883, 0x956E65E6, 0xFFE67EAA, 0xBCCF0821, 0x15E8E6EF,
0xE79BD9BA, 0x6F36CE4A, 0x9F09D4EA, 0xB07CD629, 0xA4B2AF31, 0x3F23312A, 0xA59430C6, 0xA266C035,
0x4EBC3774, 0x82CAA6FC, 0x90D0B0E0, 0xA7D81533, 0x04984AF1, 0xECDAF741, 0xCD500E7F, 0x91F62F17,
0x4DD68D76, 0xEFB04D43, 0xAA4D54CC, 0x9604DFE4, 0xD1B5E39E, 0x6A881B4C, 0x2C1FB8C1, 0x65517F46,
0x5EEA049D, 0x8C355D01, 0x877473FA, 0x0B412EFB, 0x671D5AB3, 0xDBD25292, 0x105633E9, 0xD647136D,
0xD7618C9A, 0xA10C7A37, 0xF8148E59, 0x133C89EB, 0xA927EECE, 0x61C935B7, 0x1CE5EDE1, 0x47B13C7A,
0xD2DF599C, 0xF2733F55, 0x14CE7918, 0xC737BF73, 0xF7CDEA53, 0xFDAA5B5F, 0x3D6F14DF, 0x44DB8678,
0xAFF381CA, 0x68C43EB9, 0x24342C38, 0xA3405FC2, 0x1DC37216, 0xE2250CBC, 0x3C498B28, 0x0D9541FF,
0xA8017139, 0x0CB3DE08, 0xB4E49CD8, 0x56C19064, 0xCB84617B, 0x32B670D5, 0x6C5C7448, 0xB85742D0
);
for ($i = 0; $i < 256; $i++) {
$t2[$i << 8] = (($t3[$i] << 8) & 0xFFFFFF00) | (($t3[$i] >> 24) & 0x000000FF);
$t1[$i << 16] = (($t3[$i] << 16) & 0xFFFF0000) | (($t3[$i] >> 16) & 0x0000FFFF);
$t0[$i << 24] = (($t3[$i] << 24) & 0xFF000000) | (($t3[$i] >> 8) & 0x00FFFFFF);
$dt2[$i << 8] = (($this->dt3[$i] << 8) & 0xFFFFFF00) | (($dt3[$i] >> 24) & 0x000000FF);
$dt1[$i << 16] = (($this->dt3[$i] << 16) & 0xFFFF0000) | (($dt3[$i] >> 16) & 0x0000FFFF);
$dt0[$i << 24] = (($this->dt3[$i] << 24) & 0xFF000000) | (($dt3[$i] >> 8) & 0x00FFFFFF);
}
}
/**
* Sets the key.
*
* Keys can be of any length. Rijndael, itself, requires the use of a key that's between 128-bits and 256-bits long and
* whose length is a multiple of 32. If the key is less than 256-bits and the key length isn't set, we round the length
* up to the closest valid key length, padding $key with null bytes. If the key is more than 256-bits, we trim the
* excess bits.
*
* If the key is not explicitly set, it'll be assumed to be all null bytes.
*
* @access public
* @param String $key
*/
function setKey($key)
{
$this->key = $key;
$this->changed = true;
}
/**
* Sets the initialization vector. (optional)
*
* SetIV is not required when CRYPT_RIJNDAEL_MODE_ECB is being used. If not explictly set, it'll be assumed
* to be all zero's.
*
* @access public
* @param String $iv
*/
function setIV($iv)
{
$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($iv, 0, $this->block_size), $this->block_size, chr(0));;
}
/**
* Sets the key length
*
* Valid key lengths are 128, 160, 192, 224, and 256. If the length is less than 128, it will be rounded up to
* 128. If the length is greater then 128 and invalid, it will be rounded down to the closest valid amount.
*
* @access public
* @param Integer $length
*/
function setKeyLength($length)
{
$length >>= 5;
if ($length > 8) {
$length = 8;
} else if ($length < 4) {
$length = 4;
}
$this->Nk = $length;
$this->key_size = $length << 2;
$this->explicit_key_length = true;
$this->changed = true;
}
/**
* Sets the block length
*
* Valid block lengths are 128, 160, 192, 224, and 256. If the length is less than 128, it will be rounded up to
* 128. If the length is greater then 128 and invalid, it will be rounded down to the closest valid amount.
*
* @access public
* @param Integer $length
*/
function setBlockLength($length)
{
$length >>= 5;
if ($length > 8) {
$length = 8;
} else if ($length < 4) {
$length = 4;
}
$this->Nb = $length;
$this->block_size = $length << 2;
$this->changed = true;
}
/**
* Generate CTR XOR encryption key
*
* Encrypt the output of this and XOR it against the ciphertext / plaintext to get the
* plaintext / ciphertext in CTR mode.
*
* @see Crypt_Rijndael::decrypt()
* @see Crypt_Rijndael::encrypt()
* @access public
* @param Integer $length
* @param String $iv
*/
function _generate_xor($length, &$iv)
{
$xor = '';
$block_size = $this->block_size;
$num_blocks = floor(($length + ($block_size - 1)) / $block_size);
for ($i = 0; $i < $num_blocks; $i++) {
$xor.= $iv;
for ($j = 4; $j <= $block_size; $j+=4) {
$temp = substr($iv, -$j, 4);
switch ($temp) {
case "\xFF\xFF\xFF\xFF":
$iv = substr_replace($iv, "\x00\x00\x00\x00", -$j, 4);
break;
case "\x7F\xFF\xFF\xFF":
$iv = substr_replace($iv, "\x80\x00\x00\x00", -$j, 4);
break 2;
default:
extract(unpack('Ncount', $temp));
$iv = substr_replace($iv, pack('N', $count + 1), -$j, 4);
break 2;
}
}
}
return $xor;
}
/**
* Encrypts a message.
*
* $plaintext will be padded with additional bytes such that it's length is a multiple of the block size. Other Rjindael
* implementations may or may not pad in the same manner. Other common approaches to padding and the reasons why it's
* necessary are discussed in the following
* URL:
*
* {@link http://www.di-mgt.com.au/cryptopad.html http://www.di-mgt.com.au/cryptopad.html}
*
* An alternative to padding is to, separately, send the length of the file. This is what SSH, in fact, does.
* strlen($plaintext) will still need to be a multiple of 8, however, arbitrary values can be added to make it that
* length.
*
* @see Crypt_Rijndael::decrypt()
* @access public
* @param String $plaintext
*/
function encrypt($plaintext)
{
$this->_setup();
if ($this->mode != CRYPT_RIJNDAEL_MODE_CTR) {
$plaintext = $this->_pad($plaintext);
}
$block_size = $this->block_size;
$ciphertext = '';
switch ($this->mode) {
case CRYPT_RIJNDAEL_MODE_ECB:
for ($i = 0; $i < strlen($plaintext); $i+=$block_size) {
$ciphertext.= $this->_encryptBlock(substr($plaintext, $i, $block_size));
}
break;
case CRYPT_RIJNDAEL_MODE_CBC:
$xor = $this->encryptIV;
for ($i = 0; $i < strlen($plaintext); $i+=$block_size) {
$block = substr($plaintext, $i, $block_size);
$block = $this->_encryptBlock($block ^ $xor);
$xor = $block;
$ciphertext.= $block;
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
}
break;
case CRYPT_RIJNDAEL_MODE_CTR:
$xor = $this->encryptIV;
for ($i = 0; $i < strlen($plaintext); $i+=$block_size) {
$block = substr($plaintext, $i, $block_size);
$key = $this->_encryptBlock($this->_generate_xor($block_size, $xor));
$ciphertext.= $block ^ $key;
}
if ($this->continuousBuffer) {
$this->encryptIV = $xor;
}
}
return $ciphertext;
}
/**
* Decrypts a message.
*
* If strlen($ciphertext) is not a multiple of the block size, null bytes will be added to the end of the string until
* it is.
*
* @see Crypt_Rijndael::encrypt()
* @access public
* @param String $ciphertext
*/
function decrypt($ciphertext)
{
$this->_setup();
if ($this->mode != CRYPT_RIJNDAEL_MODE_CTR) {
// we pad with chr(0) since that's what mcrypt_generic does. to quote from http://php.net/function.mcrypt-generic :
// "The data is padded with "\0" to make sure the length of the data is n * blocksize."
$ciphertext = str_pad($ciphertext, (strlen($ciphertext) + $this->block_size - 1) % $this->block_size, chr(0));
}
$block_size = $this->block_size;
$plaintext = '';
switch ($this->mode) {
case CRYPT_RIJNDAEL_MODE_ECB:
for ($i = 0; $i < strlen($ciphertext); $i+=$block_size) {
$plaintext.= $this->_decryptBlock(substr($ciphertext, $i, $block_size));
}
break;
case CRYPT_RIJNDAEL_MODE_CBC:
$xor = $this->decryptIV;
for ($i = 0; $i < strlen($ciphertext); $i+=$block_size) {
$block = substr($ciphertext, $i, $block_size);
$plaintext.= $this->_decryptBlock($block) ^ $xor;
$xor = $block;
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
}
break;
case CRYPT_RIJNDAEL_MODE_CTR:
$xor = $this->decryptIV;
for ($i = 0; $i < strlen($ciphertext); $i+=$block_size) {
$block = substr($ciphertext, $i, $block_size);
$key = $this->_encryptBlock($this->_generate_xor($block_size, $xor));
$plaintext.= $block ^ $key;
}
if ($this->continuousBuffer) {
$this->decryptIV = $xor;
}
}
return $this->mode != CRYPT_RIJNDAEL_MODE_CTR ? $this->_unpad($plaintext) : $plaintext;
}
/**
* Encrypts a block
*
* @access private
* @param String $in
* @return String
*/
function _encryptBlock($in)
{
$state = array();
$words = unpack('N*word', $in);
$w = $this->w;
$t0 = $this->t0;
$t1 = $this->t1;
$t2 = $this->t2;
$t3 = $this->t3;
$Nb = $this->Nb;
$Nr = $this->Nr;
$c = $this->c;
// addRoundKey
$i = 0;
foreach ($words as $word) {
$state[] = $word ^ $w[0][$i++];
}
// fips-197.pdf#page=19, "Figure 5. Pseudo Code for the Cipher", states that this loop has four components -
// subBytes, shiftRows, mixColumns, and addRoundKey. fips-197.pdf#page=30, "Implementation Suggestions Regarding
// Various Platforms" suggests that performs enhanced implementations are described in Rijndael-ammended.pdf.
// Rijndael-ammended.pdf#page=20, "Implementation aspects / 32-bit processor", discusses such an optimization.
// Unfortunately, the description given there is not quite correct. Per aes.spec.v316.pdf#page=19 [1],
// equation (7.4.7) is supposed to use addition instead of subtraction, so we'll do that here, as well.
// [1] http://fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.v316.pdf
$temp = array();
for ($round = 1; $round < $Nr; $round++) {
$i = 0; // $c[0] == 0
$j = $c[1];
$k = $c[2];
$l = $c[3];
while ($i < $this->Nb) {
$temp[$i] = $t0[$state[$i] & 0xFF000000] ^
$t1[$state[$j] & 0x00FF0000] ^
$t2[$state[$k] & 0x0000FF00] ^
$t3[$state[$l] & 0x000000FF] ^
$w[$round][$i];
$i++;
$j = ($j + 1) % $Nb;
$k = ($k + 1) % $Nb;
$l = ($l + 1) % $Nb;
}
for ($i = 0; $i < $Nb; $i++) {
$state[$i] = $temp[$i];
}
}
// subWord
for ($i = 0; $i < $Nb; $i++) {
$state[$i] = $this->_subWord($state[$i]);
}
// shiftRows + addRoundKey
$i = 0; // $c[0] == 0
$j = $c[1];
$k = $c[2];
$l = $c[3];
while ($i < $this->Nb) {
$temp[$i] = ($state[$i] & 0xFF000000) ^
($state[$j] & 0x00FF0000) ^
($state[$k] & 0x0000FF00) ^
($state[$l] & 0x000000FF) ^
$w[$Nr][$i];
$i++;
$j = ($j + 1) % $Nb;
$k = ($k + 1) % $Nb;
$l = ($l + 1) % $Nb;
}
$state = $temp;
array_unshift($state, 'N*');
return call_user_func_array('pack', $state);
}
/**
* Decrypts a block
*
* @access private
* @param String $in
* @return String
*/
function _decryptBlock($in)
{
$state = array();
$words = unpack('N*word', $in);
$num_states = count($state);
$dw = $this->dw;
$dt0 = $this->dt0;
$dt1 = $this->dt1;
$dt2 = $this->dt2;
$dt3 = $this->dt3;
$Nb = $this->Nb;
$Nr = $this->Nr;
$c = $this->c;
// addRoundKey
$i = 0;
foreach ($words as $word) {
$state[] = $word ^ $dw[$Nr][$i++];
}
$temp = array();
for ($round = $Nr - 1; $round > 0; $round--) {
$i = 0; // $c[0] == 0
$j = $Nb - $c[1];
$k = $Nb - $c[2];
$l = $Nb - $c[3];
while ($i < $Nb) {
$temp[$i] = $dt0[$state[$i] & 0xFF000000] ^
$dt1[$state[$j] & 0x00FF0000] ^
$dt2[$state[$k] & 0x0000FF00] ^
$dt3[$state[$l] & 0x000000FF] ^
$dw[$round][$i];
$i++;
$j = ($j + 1) % $Nb;
$k = ($k + 1) % $Nb;
$l = ($l + 1) % $Nb;
}
for ($i = 0; $i < $Nb; $i++) {
$state[$i] = $temp[$i];
}
}
// invShiftRows + invSubWord + addRoundKey
$i = 0; // $c[0] == 0
$j = $Nb - $c[1];
$k = $Nb - $c[2];
$l = $Nb - $c[3];
while ($i < $Nb) {
$temp[$i] = $dw[0][$i] ^
$this->_invSubWord(($state[$i] & 0xFF000000) |
($state[$j] & 0x00FF0000) |
($state[$k] & 0x0000FF00) |
($state[$l] & 0x000000FF));
$i++;
$j = ($j + 1) % $Nb;
$k = ($k + 1) % $Nb;
$l = ($l + 1) % $Nb;
}
$state = $temp;
array_unshift($state, 'N*');
return call_user_func_array('pack', $state);
}
/**
* Setup Rijndael
*
* Validates all the variables and calculates $Nr - the number of rounds that need to be performed - and $w - the key
* key schedule.
*
* @access private
*/
function _setup()
{
// Each number in $rcon is equal to the previous number multiplied by two in Rijndael's finite field.
// See http://en.wikipedia.org/wiki/Finite_field_arithmetic#Multiplicative_inverse
static $rcon = array(0,
0x01000000, 0x02000000, 0x04000000, 0x08000000, 0x10000000,
0x20000000, 0x40000000, 0x80000000, 0x1B000000, 0x36000000,
0x6C000000, 0xD8000000, 0xAB000000, 0x4D000000, 0x9A000000,
0x2F000000, 0x5E000000, 0xBC000000, 0x63000000, 0xC6000000,
0x97000000, 0x35000000, 0x6A000000, 0xD4000000, 0xB3000000,
0x7D000000, 0xFA000000, 0xEF000000, 0xC5000000, 0x91000000
);
if (!$this->changed) {
return;
}
if (!$this->explicit_key_length) {
// we do >> 2, here, and not >> 5, as we do above, since strlen($this->key) tells us the number of bytes - not bits
$length = strlen($this->key) >> 2;
if ($length > 8) {
$length = 8;
} else if ($length < 4) {
$length = 4;
}
$this->Nk = $length;
$this->key_size = $length << 2;
}
$this->key = str_pad(substr($this->key, 0, $this->key_size), $this->key_size, chr(0));
$this->encryptIV = $this->decryptIV = $this->iv = str_pad(substr($this->iv, 0, $this->block_size), $this->block_size, chr(0));
// see Rijndael-ammended.pdf#page=44
$this->Nr = max($this->Nk, $this->Nb) + 6;
// shift offsets for Nb = 5, 7 are defined in Rijndael-ammended.pdf#page=44,
// "Table 8: Shift offsets in Shiftrow for the alternative block lengths"
// shift offsets for Nb = 4, 6, 8 are defined in Rijndael-ammended.pdf#page=14,
// "Table 2: Shift offsets for different block lengths"
switch ($this->Nb) {
case 4:
case 5:
case 6:
$this->c = array(0, 1, 2, 3);
break;
case 7:
$this->c = array(0, 1, 2, 4);
break;
case 8:
$this->c = array(0, 1, 3, 4);
}
$key = $this->key;
$w = array_values(unpack('N*words', $key));
$length = $this->Nb * ($this->Nr + 1);
for ($i = $this->Nk; $i < $length; $i++) {
$temp = $w[$i - 1];
if ($i % $this->Nk == 0) {
// according to <http://php.net/language.types.integer>, "the size of an integer is platform-dependent".
// on a 32-bit machine, it's 32-bits, and on a 64-bit machine, it's 64-bits. on a 32-bit machine,
// 0xFFFFFFFF << 8 == 0xFFFFFF00, but on a 64-bit machine, it equals 0xFFFFFFFF00. as such, doing 'and'
// with 0xFFFFFFFF (or 0xFFFFFF00) on a 32-bit machine is unnecessary, but on a 64-bit machine, it is.
$temp = (($temp << 8) & 0xFFFFFF00) | (($temp >> 24) & 0x000000FF); // rotWord
$temp = $this->_subWord($temp) ^ $rcon[$i / $this->Nk];
} else if ($this->Nk > 6 && $i % $this->Nk == 4) {
$temp = $this->_subWord($temp);
}
$w[$i] = $w[$i - $this->Nk] ^ $temp;
}
// convert the key schedule from a vector of $Nb * ($Nr + 1) length to a matrix with $Nr + 1 rows and $Nb columns
// and generate the inverse key schedule. more specifically,
// according to <http://csrc.nist.gov/archive/aes/rijndael/Rijndael-ammended.pdf#page=23> (section 5.3.3),
// "The key expansion for the Inverse Cipher is defined as follows:
// 1. Apply the Key Expansion.
// 2. Apply InvMixColumn to all Round Keys except the first and the last one."
// also, see fips-197.pdf#page=27, "5.3.5 Equivalent Inverse Cipher"
$temp = array();
for ($i = $row = $col = 0; $i < $length; $i++, $col++) {
if ($col == $this->Nb) {
if ($row == 0) {
$this->dw[0] = $this->w[0];
} else {
// subWord + invMixColumn + invSubWord = invMixColumn
$j = 0;
while ($j < $this->Nb) {
$dw = $this->_subWord($this->w[$row][$j]);
$temp[$j] = $this->dt0[$dw & 0xFF000000] ^
$this->dt1[$dw & 0x00FF0000] ^
$this->dt2[$dw & 0x0000FF00] ^
$this->dt3[$dw & 0x000000FF];
$j++;
}
$this->dw[$row] = $temp;
}
$col = 0;
$row++;
}
$this->w[$row][$col] = $w[$i];
}
$this->dw[$row] = $this->w[$row];
$this->changed = false;
}
/**
* Performs S-Box substitutions
*
* @access private
*/
function _subWord($word)
{
static $sbox0, $sbox1, $sbox2, $sbox3;
if (empty($sbox0)) {
$sbox0 = array(
0x63, 0x7C, 0x77, 0x7B, 0xF2, 0x6B, 0x6F, 0xC5, 0x30, 0x01, 0x67, 0x2B, 0xFE, 0xD7, 0xAB, 0x76,
0xCA, 0x82, 0xC9, 0x7D, 0xFA, 0x59, 0x47, 0xF0, 0xAD, 0xD4, 0xA2, 0xAF, 0x9C, 0xA4, 0x72, 0xC0,
0xB7, 0xFD, 0x93, 0x26, 0x36, 0x3F, 0xF7, 0xCC, 0x34, 0xA5, 0xE5, 0xF1, 0x71, 0xD8, 0x31, 0x15,
0x04, 0xC7, 0x23, 0xC3, 0x18, 0x96, 0x05, 0x9A, 0x07, 0x12, 0x80, 0xE2, 0xEB, 0x27, 0xB2, 0x75,
0x09, 0x83, 0x2C, 0x1A, 0x1B, 0x6E, 0x5A, 0xA0, 0x52, 0x3B, 0xD6, 0xB3, 0x29, 0xE3, 0x2F, 0x84,
0x53, 0xD1, 0x00, 0xED, 0x20, 0xFC, 0xB1, 0x5B, 0x6A, 0xCB, 0xBE, 0x39, 0x4A, 0x4C, 0x58, 0xCF,
0xD0, 0xEF, 0xAA, 0xFB, 0x43, 0x4D, 0x33, 0x85, 0x45, 0xF9, 0x02, 0x7F, 0x50, 0x3C, 0x9F, 0xA8,
0x51, 0xA3, 0x40, 0x8F, 0x92, 0x9D, 0x38, 0xF5, 0xBC, 0xB6, 0xDA, 0x21, 0x10, 0xFF, 0xF3, 0xD2,
0xCD, 0x0C, 0x13, 0xEC, 0x5F, 0x97, 0x44, 0x17, 0xC4, 0xA7, 0x7E, 0x3D, 0x64, 0x5D, 0x19, 0x73,
0x60, 0x81, 0x4F, 0xDC, 0x22, 0x2A, 0x90, 0x88, 0x46, 0xEE, 0xB8, 0x14, 0xDE, 0x5E, 0x0B, 0xDB,
0xE0, 0x32, 0x3A, 0x0A, 0x49, 0x06, 0x24, 0x5C, 0xC2, 0xD3, 0xAC, 0x62, 0x91, 0x95, 0xE4, 0x79,
0xE7, 0xC8, 0x37, 0x6D, 0x8D, 0xD5, 0x4E, 0xA9, 0x6C, 0x56, 0xF4, 0xEA, 0x65, 0x7A, 0xAE, 0x08,
0xBA, 0x78, 0x25, 0x2E, 0x1C, 0xA6, 0xB4, 0xC6, 0xE8, 0xDD, 0x74, 0x1F, 0x4B, 0xBD, 0x8B, 0x8A,
0x70, 0x3E, 0xB5, 0x66, 0x48, 0x03, 0xF6, 0x0E, 0x61, 0x35, 0x57, 0xB9, 0x86, 0xC1, 0x1D, 0x9E,
0xE1, 0xF8, 0x98, 0x11, 0x69, 0xD9, 0x8E, 0x94, 0x9B, 0x1E, 0x87, 0xE9, 0xCE, 0x55, 0x28, 0xDF,
0x8C, 0xA1, 0x89, 0x0D, 0xBF, 0xE6, 0x42, 0x68, 0x41, 0x99, 0x2D, 0x0F, 0xB0, 0x54, 0xBB, 0x16
);
$sbox1 = array();
$sbox2 = array();
$sbox3 = array();
for ($i = 0; $i < 256; $i++) {
$sbox1[$i << 8] = $sbox0[$i] << 8;
$sbox2[$i << 16] = $sbox0[$i] << 16;
$sbox3[$i << 24] = $sbox0[$i] << 24;
}
}
return $sbox0[$word & 0x000000FF] |
$sbox1[$word & 0x0000FF00] |
$sbox2[$word & 0x00FF0000] |
$sbox3[$word & 0xFF000000];
}
/**
* Performs inverse S-Box substitutions
*
* @access private
*/
function _invSubWord($word)
{
static $sbox0, $sbox1, $sbox2, $sbox3;
if (empty($sbox0)) {
$sbox0 = array(
0x52, 0x09, 0x6A, 0xD5, 0x30, 0x36, 0xA5, 0x38, 0xBF, 0x40, 0xA3, 0x9E, 0x81, 0xF3, 0xD7, 0xFB,
0x7C, 0xE3, 0x39, 0x82, 0x9B, 0x2F, 0xFF, 0x87, 0x34, 0x8E, 0x43, 0x44, 0xC4, 0xDE, 0xE9, 0xCB,
0x54, 0x7B, 0x94, 0x32, 0xA6, 0xC2, 0x23, 0x3D, 0xEE, 0x4C, 0x95, 0x0B, 0x42, 0xFA, 0xC3, 0x4E,
0x08, 0x2E, 0xA1, 0x66, 0x28, 0xD9, 0x24, 0xB2, 0x76, 0x5B, 0xA2, 0x49, 0x6D, 0x8B, 0xD1, 0x25,
0x72, 0xF8, 0xF6, 0x64, 0x86, 0x68, 0x98, 0x16, 0xD4, 0xA4, 0x5C, 0xCC, 0x5D, 0x65, 0xB6, 0x92,
0x6C, 0x70, 0x48, 0x50, 0xFD, 0xED, 0xB9, 0xDA, 0x5E, 0x15, 0x46, 0x57, 0xA7, 0x8D, 0x9D, 0x84,
0x90, 0xD8, 0xAB, 0x00, 0x8C, 0xBC, 0xD3, 0x0A, 0xF7, 0xE4, 0x58, 0x05, 0xB8, 0xB3, 0x45, 0x06,
0xD0, 0x2C, 0x1E, 0x8F, 0xCA, 0x3F, 0x0F, 0x02, 0xC1, 0xAF, 0xBD, 0x03, 0x01, 0x13, 0x8A, 0x6B,
0x3A, 0x91, 0x11, 0x41, 0x4F, 0x67, 0xDC, 0xEA, 0x97, 0xF2, 0xCF, 0xCE, 0xF0, 0xB4, 0xE6, 0x73,
0x96, 0xAC, 0x74, 0x22, 0xE7, 0xAD, 0x35, 0x85, 0xE2, 0xF9, 0x37, 0xE8, 0x1C, 0x75, 0xDF, 0x6E,
0x47, 0xF1, 0x1A, 0x71, 0x1D, 0x29, 0xC5, 0x89, 0x6F, 0xB7, 0x62, 0x0E, 0xAA, 0x18, 0xBE, 0x1B,
0xFC, 0x56, 0x3E, 0x4B, 0xC6, 0xD2, 0x79, 0x20, 0x9A, 0xDB, 0xC0, 0xFE, 0x78, 0xCD, 0x5A, 0xF4,
0x1F, 0xDD, 0xA8, 0x33, 0x88, 0x07, 0xC7, 0x31, 0xB1, 0x12, 0x10, 0x59, 0x27, 0x80, 0xEC, 0x5F,
0x60, 0x51, 0x7F, 0xA9, 0x19, 0xB5, 0x4A, 0x0D, 0x2D, 0xE5, 0x7A, 0x9F, 0x93, 0xC9, 0x9C, 0xEF,
0xA0, 0xE0, 0x3B, 0x4D, 0xAE, 0x2A, 0xF5, 0xB0, 0xC8, 0xEB, 0xBB, 0x3C, 0x83, 0x53, 0x99, 0x61,
0x17, 0x2B, 0x04, 0x7E, 0xBA, 0x77, 0xD6, 0x26, 0xE1, 0x69, 0x14, 0x63, 0x55, 0x21, 0x0C, 0x7D
);
$sbox1 = array();
$sbox2 = array();
$sbox3 = array();
for ($i = 0; $i < 256; $i++) {
$sbox1[$i << 8] = $sbox0[$i] << 8;
$sbox2[$i << 16] = $sbox0[$i] << 16;
$sbox3[$i << 24] = $sbox0[$i] << 24;
}
}
return $sbox0[$word & 0x000000FF] |
$sbox1[$word & 0x0000FF00] |
$sbox2[$word & 0x00FF0000] |
$sbox3[$word & 0xFF000000];
}
/**
* Pad "packets".
*
* Rijndael works by encrypting between sixteen and thirty-two bytes at a time, provided that number is also a multiple
* of four. If you ever need to encrypt or decrypt something that isn't of the proper length, it becomes necessary to
* pad the input so that it is of the proper length.
*
* Padding is enabled by default. Sometimes, however, it is undesirable to pad strings. Such is the case in SSH,
* where "packets" are padded with random bytes before being encrypted. Unpad these packets and you risk stripping
* away characters that shouldn't be stripped away. (SSH knows how many bytes are added because the length is
* transmitted separately)
*
* @see Crypt_Rijndael::disablePadding()
* @access public
*/
function enablePadding()
{
$this->padding = true;
}
/**
* Do not pad packets.
*
* @see Crypt_Rijndael::enablePadding()
* @access public
*/
function disablePadding()
{
$this->padding = false;
}
/**
* Pads a string
*
* Pads a string using the RSA PKCS padding standards so that its length is a multiple of the blocksize.
* $block_size - (strlen($text) % $block_size) bytes are added, each of which is equal to
* chr($block_size - (strlen($text) % $block_size)
*
* If padding is disabled and $text is not a multiple of the blocksize, the string will be padded regardless
* and padding will, hence forth, be enabled.
*
* @see Crypt_Rijndael::_unpad()
* @access private
*/
function _pad($text)
{
$length = strlen($text);
if (!$this->padding) {
if ($length % $this->block_size == 0) {
return $text;
} else {
user_error("The plaintext's length ($length) is not a multiple of the block size ({$this->block_size})", E_USER_NOTICE);
$this->padding = true;
}
}
$pad = $this->block_size - ($length % $this->block_size);
return str_pad($text, $length + $pad, chr($pad));
}
/**
* Unpads a string.
*
* If padding is enabled and the reported padding length is invalid the encryption key will be assumed to be wrong
* and false will be returned.
*
* @see Crypt_Rijndael::_pad()
* @access private
*/
function _unpad($text)
{
if (!$this->padding) {
return $text;
}
$length = ord($text[strlen($text) - 1]);
if (!$length || $length > $this->block_size) {
return false;
}
return substr($text, 0, -$length);
}
/**
* Treat consecutive "packets" as if they are a continuous buffer.
*
* Say you have a 32-byte plaintext $plaintext. Using the default behavior, the two following code snippets
* will yield different outputs:
*
* <code>
* echo $rijndael->encrypt(substr($plaintext, 0, 16));
* echo $rijndael->encrypt(substr($plaintext, 16, 16));
* </code>
* <code>
* echo $rijndael->encrypt($plaintext);
* </code>
*
* The solution is to enable the continuous buffer. Although this will resolve the above discrepancy, it creates
* another, as demonstrated with the following:
*
* <code>
* $rijndael->encrypt(substr($plaintext, 0, 16));
* echo $rijndael->decrypt($des->encrypt(substr($plaintext, 16, 16)));
* </code>
* <code>
* echo $rijndael->decrypt($des->encrypt(substr($plaintext, 16, 16)));
* </code>
*
* With the continuous buffer disabled, these would yield the same output. With it enabled, they yield different
* outputs. The reason is due to the fact that the initialization vector's change after every encryption /
* decryption round when the continuous buffer is enabled. When it's disabled, they remain constant.
*
* Put another way, when the continuous buffer is enabled, the state of the Crypt_Rijndael() object changes after each
* encryption / decryption round, whereas otherwise, it'd remain constant. For this reason, it's recommended that
* continuous buffers not be used. They do offer better security and are, in fact, sometimes required (SSH uses them),
* however, they are also less intuitive and more likely to cause you problems.
*
* @see Crypt_Rijndael::disableContinuousBuffer()
* @access public
*/
function enableContinuousBuffer()
{
$this->continuousBuffer = true;
}
/**
* Treat consecutive packets as if they are a discontinuous buffer.
*
* The default behavior.
*
* @see Crypt_Rijndael::enableContinuousBuffer()
* @access public
*/
function disableContinuousBuffer()
{
$this->continuousBuffer = false;
$this->encryptIV = $this->iv;
$this->decryptIV = $this->iv;
}
/**
* String Shift
*
* Inspired by array_shift
*
* @param String $string
* @param optional Integer $index
* @return String
* @access private
*/
function _string_shift(&$string, $index = 1)
{
$substr = substr($string, 0, $index);
$string = substr($string, $index);
return $substr;
}
}
// vim: ts=4:sw=4:et:
// vim6: fdl=1:
