<?php
/**
* AES cipher
*
*/
class AES
{
// The number of 32-bit words comprising the plaintext and columns comrising the state matrix of an AES cipher.
private static $Nb = 4;
// The number of 32-bit words comprising the cipher key in this AES cipher.
private $Nk;
// The number of rounds in this AES cipher.
private $Nr;
// The S-Box substitution table.
private static $sBox = 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
);
// The inverse S-Box substitution table.
private static $invSBox = 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
);
// Log table based on 0xe5
private static $ltable = array(
0x00, 0xff, 0xc8, 0x08, 0x91, 0x10, 0xd0, 0x36,
0x5a, 0x3e, 0xd8, 0x43, 0x99, 0x77, 0xfe, 0x18,
0x23, 0x20, 0x07, 0x70, 0xa1, 0x6c, 0x0c, 0x7f,
0x62, 0x8b, 0x40, 0x46, 0xc7, 0x4b, 0xe0, 0x0e,
0xeb, 0x16, 0xe8, 0xad, 0xcf, 0xcd, 0x39, 0x53,
0x6a, 0x27, 0x35, 0x93, 0xd4, 0x4e, 0x48, 0xc3,
0x2b, 0x79, 0x54, 0x28, 0x09, 0x78, 0x0f, 0x21,
0x90, 0x87, 0x14, 0x2a, 0xa9, 0x9c, 0xd6, 0x74,
0xb4, 0x7c, 0xde, 0xed, 0xb1, 0x86, 0x76, 0xa4,
0x98, 0xe2, 0x96, 0x8f, 0x02, 0x32, 0x1c, 0xc1,
0x33, 0xee, 0xef, 0x81, 0xfd, 0x30, 0x5c, 0x13,
0x9d, 0x29, 0x17, 0xc4, 0x11, 0x44, 0x8c, 0x80,
0xf3, 0x73, 0x42, 0x1e, 0x1d, 0xb5, 0xf0, 0x12,
0xd1, 0x5b, 0x41, 0xa2, 0xd7, 0x2c, 0xe9, 0xd5,
0x59, 0xcb, 0x50, 0xa8, 0xdc, 0xfc, 0xf2, 0x56,
0x72, 0xa6, 0x65, 0x2f, 0x9f, 0x9b, 0x3d, 0xba,
0x7d, 0xc2, 0x45, 0x82, 0xa7, 0x57, 0xb6, 0xa3,
0x7a, 0x75, 0x4f, 0xae, 0x3f, 0x37, 0x6d, 0x47,
0x61, 0xbe, 0xab, 0xd3, 0x5f, 0xb0, 0x58, 0xaf,
0xca, 0x5e, 0xfa, 0x85, 0xe4, 0x4d, 0x8a, 0x05,
0xfb, 0x60, 0xb7, 0x7b, 0xb8, 0x26, 0x4a, 0x67,
0xc6, 0x1a, 0xf8, 0x69, 0x25, 0xb3, 0xdb, 0xbd,
0x66, 0xdd, 0xf1, 0xd2, 0xdf, 0x03, 0x8d, 0x34,
0xd9, 0x92, 0x0d, 0x63, 0x55, 0xaa, 0x49, 0xec,
0xbc, 0x95, 0x3c, 0x84, 0x0b, 0xf5, 0xe6, 0xe7,
0xe5, 0xac, 0x7e, 0x6e, 0xb9, 0xf9, 0xda, 0x8e,
0x9a, 0xc9, 0x24, 0xe1, 0x0a, 0x15, 0x6b, 0x3a,
0xa0, 0x51, 0xf4, 0xea, 0xb2, 0x97, 0x9e, 0x5d,
0x22, 0x88, 0x94, 0xce, 0x19, 0x01, 0x71, 0x4c,
0xa5, 0xe3, 0xc5, 0x31, 0xbb, 0xcc, 0x1f, 0x2d,
0x3b, 0x52, 0x6f, 0xf6, 0x2e, 0x89, 0xf7, 0xc0,
0x68, 0x1b, 0x64, 0x04, 0x06, 0xbf, 0x83, 0x38
);
// Inverse log table
private static $atable = array(
0x01, 0xe5, 0x4c, 0xb5, 0xfb, 0x9f, 0xfc, 0x12,
0x03, 0x34, 0xd4, 0xc4, 0x16, 0xba, 0x1f, 0x36,
0x05, 0x5c, 0x67, 0x57, 0x3a, 0xd5, 0x21, 0x5a,
0x0f, 0xe4, 0xa9, 0xf9, 0x4e, 0x64, 0x63, 0xee,
0x11, 0x37, 0xe0, 0x10, 0xd2, 0xac, 0xa5, 0x29,
0x33, 0x59, 0x3b, 0x30, 0x6d, 0xef, 0xf4, 0x7b,
0x55, 0xeb, 0x4d, 0x50, 0xb7, 0x2a, 0x07, 0x8d,
0xff, 0x26, 0xd7, 0xf0, 0xc2, 0x7e, 0x09, 0x8c,
0x1a, 0x6a, 0x62, 0x0b, 0x5d, 0x82, 0x1b, 0x8f,
0x2e, 0xbe, 0xa6, 0x1d, 0xe7, 0x9d, 0x2d, 0x8a,
0x72, 0xd9, 0xf1, 0x27, 0x32, 0xbc, 0x77, 0x85,
0x96, 0x70, 0x08, 0x69, 0x56, 0xdf, 0x99, 0x94,
0xa1, 0x90, 0x18, 0xbb, 0xfa, 0x7a, 0xb0, 0xa7,
0xf8, 0xab, 0x28, 0xd6, 0x15, 0x8e, 0xcb, 0xf2,
0x13, 0xe6, 0x78, 0x61, 0x3f, 0x89, 0x46, 0x0d,
0x35, 0x31, 0x88, 0xa3, 0x41, 0x80, 0xca, 0x17,
0x5f, 0x53, 0x83, 0xfe, 0xc3, 0x9b, 0x45, 0x39,
0xe1, 0xf5, 0x9e, 0x19, 0x5e, 0xb6, 0xcf, 0x4b,
0x38, 0x04, 0xb9, 0x2b, 0xe2, 0xc1, 0x4a, 0xdd,
0x48, 0x0c, 0xd0, 0x7d, 0x3d, 0x58, 0xde, 0x7c,
0xd8, 0x14, 0x6b, 0x87, 0x47, 0xe8, 0x79, 0x84,
0x73, 0x3c, 0xbd, 0x92, 0xc9, 0x23, 0x8b, 0x97,
0x95, 0x44, 0xdc, 0xad, 0x40, 0x65, 0x86, 0xa2,
0xa4, 0xcc, 0x7f, 0xec, 0xc0, 0xaf, 0x91, 0xfd,
0xf7, 0x4f, 0x81, 0x2f, 0x5b, 0xea, 0xa8, 0x1c,
0x02, 0xd1, 0x98, 0x71, 0xed, 0x25, 0xe3, 0x24,
0x06, 0x68, 0xb3, 0x93, 0x2c, 0x6f, 0x3e, 0x6c,
0x0a, 0xb8, 0xce, 0xae, 0x74, 0xb1, 0x42, 0xb4,
0x1e, 0xd3, 0x49, 0xe9, 0x9c, 0xc8, 0xc6, 0xc7,
0x22, 0x6e, 0xdb, 0x20, 0xbf, 0x43, 0x51, 0x52,
0x66, 0xb2, 0x76, 0x60, 0xda, 0xc5, 0xf3, 0xf6,
0xaa, 0xcd, 0x9a, 0xa0, 0x75, 0x54, 0x0e, 0x01
);
// The key schedule in this AES cipher.
private $w = array(); // Nb*(Nr+1) 32-bit words
// The state matrix in this AES cipher with Nb columns and 4 rows
private $s = array(array());
// The block cipher mode of operation
private $mode;
// The initialization vector used in advanced cipher modes
private $iv;
/**
* Constructs an AES cipher using a specific key.
*
* @throws LengthException if the initialization vector or key is not the
* appropriate length.
*/
public function __construct($z, $mode = 'ECB', $iv = null)
{
$this->mode = strtoupper($mode);
$this->iv = $iv;
$this->Nk = strlen($z)/4;
$this->Nr = $this->Nk + self::$Nb + 2;
if ($this->mode != 'ECB' && strlen($this->iv) != 16) {
throw new \LengthException(
'The initialization vector must be 128 bits (or 16 characters) long.'
);
}
if ($this->Nk != 4 && $this->Nk != 6 && $this->Nk != 8) {
throw new \LengthException(
'Key is ' . ($this->Nk*32) . ' bits long. *not* 128, 192, or 256.'
);
}
$this->Nr = $this->Nk+self::$Nb+2;
$this->keyExpansion($z); // places expanded key in w
}
public function __destruct()
{
unset($this->w);
unset($this->s);
}
/**
* Encrypts an aribtrary length String.
* @params plaintext string
* @returns ciphertext string
*/
public function encrypt($x)
{
$t = ''; // 16-byte block to hold the temporary input of the cipher
$y = ''; // returned cipher text;
$y_block = $this->iv; // 16-byte block to hold the temporary output of the cipher
$xsize = strlen($x);
switch ($this->mode) {
case 'ECB':
// put a 16-byte block into t, ecnrypt it and add it to the result
for ($i = 0; $i < $xsize; $i += 16) {
for ($j = 0; $j < 16; $j++) {
if (($i+$j)<$xsize) {
$t[$j] = $x[$i+$j];
} else {
$t[$j] = chr(0);
}
}
$y_block = $this->encryptBlock($t);
$y .= $y_block;
}
break;
case 'CBC':
// put a 16-byte block into t, ecnrypt it and add it to the result
for ($i = 0; $i < $xsize; $i += 16) {
for ($j=0; $j<16; $j++) {
// XOR this block of plaintext with the initialization vector
$t[$j] = chr(ord(($i+$j)<$xsize ? $x[$i+$j] : chr(0)) ^ ord($y_block[$j]));
}
$y_block = $this->encryptBlock($t);
$y .= $y_block;
}
break;
case 'CFB':
for ($i = 0; $i < $xsize; $i += 16) {
// Encrypt the initialization vector/cipher output then XOR with the plaintext
$y_block = $this->encryptBlock($y_block);
for ($j = 0; $j < 16; $j++) {
// XOR the cipher output with the plaintext.
$y_block[$j] = chr(ord(($i+$j)<$xsize ? $x[$i+$j] : chr(0)) ^ ord($y_block[$j]));
}
$y .= $y_block;
}
break;
case 'OFB':
for ($i = 0; $i < $xsize; $i += 16) {
// Encrypt the initialization vector/cipher output then XOR with the plaintext
$t = $this->encryptBlock($y_block);
for ($j = 0; $j < 16; $j++) {
// XOR the cipher output with the plaintext.
$y_block[$j] = chr(ord(($i+$j)<$xsize ? $x[$i+$j] : chr(0)) ^ ord($t[$j]));
}
$y .= $y_block;
$y_block = $t;
}
break;
}
return $y;
}
/**
* Decrypts an aribtrary length String.
* @params ciphertext string
* @returns plaintext string
*/
public function decrypt($y)
{
$t = array(); // 16-byte block
$x = ''; // returned plain text;
$y_block = $this->iv;
$x_block = '';
// put a 16-byte block into t
$ysize = strlen($y);
switch ($this->mode) {
case 'ECB':
for ($i = 0; $i < $ysize; $i += 16) {
for ($j = 0; $j < 16; $j++) {
if (($i+$j) < $ysize) {
$t[$j] = $y[$i+$j];
} else {
$t[$j] = chr(0);
}
}
$x_block = $this->decryptBlock($t);
$x .= $x_block;
}
break;
case 'CBC':
for ($i = 0; $i < $ysize; $i += 16) {
for ($j = 0; $j < 16; $j++) {
if (($i+$j)<$ysize) {
$t[$j] = $y[$i+$j];
} else {
$t[$j] = chr(0);
}
}
$x_block = $this->decryptBlock($t);
// XOR the iv/previous cipher block with this decrypted cipher block
for ($j = 0; $j < 16; $j++) {
$x_block[$j] = chr(ord($x_block[$j]) ^ ord($y_block[$j]));
}
$y_block = $t;
$x .= $x_block;
}
break;
case 'CFB':
for ($i = 0; $i < $ysize; $i += 16) {
// Encrypt the initialization vector/cipher output then XOR with the ciphertext
$x_block = $this->encryptBlock($y_block);
for ($j = 0; $j < 16; $j++) {
// XOR the cipher output with the ciphertext.
$x_block[$j] = chr(ord(($i+$j)<$ysize ? $y[$i+$j] : chr(0)) ^ ord($x_block[$j]));
$y_block[$j] = $y[$i+$j];
}
$x .= $x_block;
}
break;
case 'OFB':
$x = $this->encrypt($y);
break;
}
return rtrim($x, chr(0)); // Remove any buffer residue on return.
}
/**
* Encrypts the 16-byte plain text.
* @params 16-byte plaintext string
* @returns 16-byte ciphertext string
*/
public function encryptBlock($x)
{
$y = ''; // 16-byte string
// place input x into the initial state matrix in column order
for ($i = 0; $i <4*self::$Nb; $i++) {
// we want integerger division for the second index
$this->s[$i%4][($i-$i%self::$Nb)/self::$Nb] = ord($x[$i]);
}
// add round key
$this->addRoundKey(0);
for ($i = 1; $i < $this->Nr; $i++) {
// substitute bytes
$this->subBytes();
// shift rows
$this->shiftRows();
// mix columns
$this->mixColumns();
// add round key
$this->addRoundKey($i);
}
// substitute bytes
$this->subBytes();
// shift rows
$this->shiftRows();
// add round key
$this->addRoundKey($i);
// place state matrix s into y in column order
for ($i = 0; $i < 4*self::$Nb; $i++) {
$y .= chr($this->s[$i%4][($i-$i%self::$Nb)/self::$Nb]);
}
return $y;
}
/**
* Decrypts the 16-byte cipher text.
* @params 16-byte ciphertext string
* @returns 16-byte plaintext string
*/
public function decryptBlock($y)
{
$x = ''; // 16-byte string
// place input y into the initial state matrix in column order
for ($i = 0; $i < 4*self::$Nb; $i++) {
$this->s[$i%4][($i-$i%self::$Nb)/self::$Nb] = ord($y[$i]);
}
// add round key
$this->addRoundKey($this->Nr);
for ($i = $this->Nr-1; $i > 0; $i--) {
// inverse shift rows
$this->invShiftRows();
// inverse sub bytes
$this->invSubBytes();
// add round key
$this->addRoundKey($i);
// inverse mix columns
$this->invMixColumns();
}
// inverse shift rows
$this->invShiftRows();
// inverse sub bytes
$this->invSubBytes();
// add round key
$this->addRoundKey($i);
// place state matrix s into x in column order
for ($i = 0; $i < 4*self::$Nb; $i++) {
// Used to remove filled null characters.
$x .= chr($this->s[$i%4][($i-$i%self::$Nb)/self::$Nb]);
}
return $x;
}
/**
* Makes a big key out of a small one
* @returns void
*/
private function keyExpansion($z)
{
// Rcon is the round constant
static $Rcon = array(
0x00000000,
0x01000000,
0x02000000,
0x04000000,
0x08000000,
0x10000000,
0x20000000,
0x40000000,
0x80000000,
0x1b000000,
0x36000000,
0x6c000000,
0xd8000000,
0xab000000,
0x4d000000,
0x9a000000,
0x2f000000
);
$temp = 0; // temporary 32-bit word
// the first Nk words of w are the cipher key z
for ($i = 0; $i < $this->Nk; $i++) {
$this->w[$i] = 0;
// fill an entire word of expanded key w
// by pushing 4 bytes into the w[i] word
$this->w[$i] = ord($z[4*$i]); // add a byte in
$this->w[$i] <<= 8; // make room for the next byte
$this->w[$i] += ord($z[4*$i+1]);
$this->w[$i] <<= 8;
$this->w[$i] += ord($z[4*$i+2]);
$this->w[$i] <<= 8;
$this->w[$i] += ord($z[4*$i+3]);
}
for (; $i < self::$Nb*($this->Nr+1); $i++) {
$temp = $this->w[$i-1];
if ($i%$this->Nk == 0) {
$temp = $this->subWord($this->rotWord($temp)) ^ $Rcon[$i/$this->Nk];
} elseif ($this->Nk > 6 && $i%$this->Nk == 4) {
$temp = $this->subWord($temp);
}
$this->w[$i] = $this->w[$i-$this->Nk] ^ $temp;
self::make32BitWord($this->w[$i]);
}
}
/**
* Adds the key schedule for a round to a state matrix.
* @returns void
*/
private function addRoundKey($round)
{
$temp = '';
for ($i = 0; $i < 4; $i++) {
for ($j = 0; $j < self::$Nb; $j++) {
// place the i-th byte of the j-th word from expanded key w into temp
$temp = $this->w[$round*self::$Nb+$j] >> (3-$i)*8;
// Cast temp from a 32-bit word into an 8-bit byte.
$temp %= 256;
// Can't do unsigned shifts, so we need to make this temp positive
$temp = ($temp < 0 ? (256 + $temp) : $temp);
$this->s[$i][$j] ^= $temp; // xor temp with the byte at location (i,j) of the state
}
}
}
/**
* Unmixes each column of a state matrix.
* @returns void
*/
private function invMixColumns()
{
$s0 = $s1 = $s2 = $s3= '';
// There are Nb columns
for ($i = 0; $i < self::$Nb; $i++) {
$s0 = $this->s[0][$i];
$s1 = $this->s[1][$i];
$s2 = $this->s[2][$i];
$s3 = $this->s[3][$i];
$this->s[0][$i] = $this->mult(0x0e, $s0)
^ $this->mult(0x0b, $s1)
^ $this->mult(0x0d, $s2)
^ $this->mult(0x09, $s3);
$this->s[1][$i] = $this->mult(0x09, $s0)
^ $this->mult(0x0e, $s1)
^ $this->mult(0x0b, $s2)
^ $this->mult(0x0d, $s3);
$this->s[2][$i] = $this->mult(0x0d, $s0)
^ $this->mult(0x09, $s1)
^ $this->mult(0x0e, $s2)
^ $this->mult(0x0b, $s3);
$this->s[3][$i] = $this->mult(0x0b, $s0)
^ $this->mult(0x0d, $s1)
^ $this->mult(0x09, $s2)
^ $this->mult(0x0e, $s3);
}
}
/**
* Applies an inverse cyclic shift to the last 3 rows of a state matrix.
* @returns void
*/
private function invShiftRows()
{
$temp = array();
for ($i = 1; $i < 4; $i++) {
for ($j = 0; $j < self::$Nb; $j++) {
$temp[($i+$j)%self::$Nb] = $this->s[$i][$j];
}
for ($j = 0; $j < self::$Nb; $j++) {
$this->s[$i][$j] = $temp[$j];
}
}
}
/**
* Applies inverse S-Box substitution to each byte of a state matrix.
* @returns void
*/
private function invSubBytes()
{
for ($i = 0; $i < 4; $i++) {
for ($j = 0; $j < self::$Nb; $j++) {
$this->s[$i][$j] = self::$invSBox[$this->s[$i][$j]];
}
}
}
/**
* Mixes each column of a state matrix.
* @returns void
*/
private function mixColumns()
{
$s0 = $s1 = $s2 = $s3= '';
// There are Nb columns
for ($i = 0; $i < self::$Nb; $i++) {
$s0 = $this->s[0][$i];
$s1 = $this->s[1][$i];
$s2 = $this->s[2][$i];
$s3 = $this->s[3][$i];
$this->s[0][$i] = $this->mult(0x02, $s0)
^ $this->mult(0x03, $s1)
^ $this->mult(0x01, $s2)
^ $this->mult(0x01, $s3);
$this->s[1][$i] = $this->mult(0x01, $s0)
^ $this->mult(0x02, $s1)
^ $this->mult(0x03, $s2)
^ $this->mult(0x01, $s3);
$this->s[2][$i] = $this->mult(0x01, $s0)
^ $this->mult(0x01, $s1)
^ $this->mult(0x02, $s2)
^ $this->mult(0x03, $s3);
$this->s[3][$i] = $this->mult(0x03, $s0)
^ $this->mult(0x01, $s1)
^ $this->mult(0x01, $s2)
^ $this->mult(0x02, $s3);
}
}
/**
* Applies a cyclic shift to the last 3 rows of a state matrix.
* @returns void
*/
private function shiftRows()
{
$temp = array();
for ($i = 1; $i < 4; $i++) {
for ($j = 0; $j < self::$Nb; $j++) {
$temp[$j] = $this->s[$i][($j+$i)%self::$Nb];
}
for ($j = 0; $j < self::$Nb; $j++) {
$this->s[$i][$j] = $temp[$j];
}
}
}
/**
* Applies S-Box substitution to each byte of a state matrix.
* @returns void
*/
private function subBytes()
{
for ($i = 0; $i < 4; $i++) {
for ($j = 0; $j < self::$Nb; $j++) {
$this->s[$i][$j] = self::$sBox[$this->s[$i][$j]];
}
}
}
/**
* Multiplies two polynomials a(x), b(x) in GF(2^8) modulo the irreducible polynomial m(x) = x^8+x^4+x^3+x+1
* @returns 8-bit value
*/
private static function mult($a, $b)
{
$sum = self::$ltable[$a] + self::$ltable[$b];
$sum %= 255;
// Get the antilog
$sum = self::$atable[$sum];
return ($a == 0 ? 0 : ($b == 0 ? 0 : $sum));
}
/**
* Applies a cyclic permutation to a 4-byte word.
* @returns 32-bit int
*/
private static function rotWord($w)
{
$temp = $w >> 24; // put the first 8-bits into temp
$w <<= 8; // make room for temp to fill the lower end of the word
self::make32BitWord($w);
// Can't do unsigned shifts, so we need to make this temp positive
$temp += $temp < 0 ? 256 : 0;
$w += $temp;
return $w;
}
/**
* Applies S-box substitution to each byte of a 4-byte word.
* @returns 32-bit int
*/
private static function subWord($w)
{
$temp = 0;
// loop through 4 bytes of a word
for ($i = 0; $i < 4; $i++) {
$temp = $w >> 24; // put the first 8-bits into temp
// Can't do unsigned shifts, so we need to make this temp positive
$temp += $temp < 0 ? 256 : 0;
$w <<= 8; // make room for the substituted byte in w;
self::make32BitWord($w);
$w += self::$sBox[$temp]; // add the substituted byte back
}
self::make32BitWord($w);
return $w;
}
/**
* Reduces a 64-bit word to a 32-bit word
* @returns void
*/
private static function make32BitWord(&$w)
{
// Reduce this 64-bit word to 32-bits on 64-bit machines
$w &= 0x00000000FFFFFFFF;
}
}