364 lines
16 KiB
PHP
364 lines
16 KiB
PHP
<?php
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* AES implementation in PHP */
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/* (c) Chris Veness 2005-2014 www.movable-type.co.uk/scripts */
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/* Right of free use is granted for all commercial or non-commercial use under CC-BY licence. */
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/* No warranty of any form is offered. */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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class Aes
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{
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/**
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* AES Cipher function [§5.1]: encrypt 'input' with Rijndael algorithm
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*
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* @param input message as byte-array (16 bytes)
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* @param w key schedule as 2D byte-array (Nr+1 x Nb bytes) -
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* generated from the cipher key by keyExpansion()
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* @return ciphertext as byte-array (16 bytes)
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*/
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public static function cipher($input, $w)
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{
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$Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
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$Nr = count($w) / $Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys
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$state = array(); // initialise 4xNb byte-array 'state' with input [§3.4]
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for ($i = 0; $i < 4 * $Nb; $i++) $state[$i % 4][floor($i / 4)] = $input[$i];
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$state = self::addRoundKey($state, $w, 0, $Nb);
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for ($round = 1; $round < $Nr; $round++) { // apply Nr rounds
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$state = self::subBytes($state, $Nb);
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$state = self::shiftRows($state, $Nb);
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$state = self::mixColumns($state, $Nb);
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$state = self::addRoundKey($state, $w, $round, $Nb);
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}
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$state = self::subBytes($state, $Nb);
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$state = self::shiftRows($state, $Nb);
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$state = self::addRoundKey($state, $w, $Nr, $Nb);
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$output = array(4 * $Nb); // convert state to 1-d array before returning [§3.4]
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for ($i = 0; $i < 4 * $Nb; $i++) $output[$i] = $state[$i % 4][floor($i / 4)];
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return $output;
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}
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/**
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* Xor Round Key into state S [§5.1.4].
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*/
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private static function addRoundKey($state, $w, $rnd, $Nb)
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{
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for ($r = 0; $r < 4; $r++) {
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for ($c = 0; $c < $Nb; $c++) $state[$r][$c] ^= $w[$rnd * 4 + $c][$r];
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}
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return $state;
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}
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/**
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* Apply SBox to state S [§5.1.1].
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*/
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private static function subBytes($s, $Nb)
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{
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for ($r = 0; $r < 4; $r++) {
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for ($c = 0; $c < $Nb; $c++) $s[$r][$c] = self::$sBox[$s[$r][$c]];
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}
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return $s;
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}
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/**
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* Shift row r of state S left by r bytes [§5.1.2].
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*/
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private static function shiftRows($s, $Nb)
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{
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$t = array(4);
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for ($r = 1; $r < 4; $r++) {
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for ($c = 0; $c < 4; $c++) $t[$c] = $s[$r][($c + $r) % $Nb]; // shift into temp copy
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for ($c = 0; $c < 4; $c++) $s[$r][$c] = $t[$c]; // and copy back
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} // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
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return $s; // see fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
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}
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/**
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* Combine bytes of each col of state S [§5.1.3].
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*/
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private static function mixColumns($s, $Nb)
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{
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for ($c = 0; $c < 4; $c++) {
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$a = array(4); // 'a' is a copy of the current column from 's'
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$b = array(4); // 'b' is a•{02} in GF(2^8)
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for ($i = 0; $i < 4; $i++) {
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$a[$i] = $s[$i][$c];
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$b[$i] = $s[$i][$c] & 0x80 ? $s[$i][$c] << 1 ^ 0x011b : $s[$i][$c] << 1;
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}
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// a[n] ^ b[n] is a•{03} in GF(2^8)
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$s[0][$c] = $b[0] ^ $a[1] ^ $b[1] ^ $a[2] ^ $a[3]; // 2*a0 + 3*a1 + a2 + a3
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$s[1][$c] = $a[0] ^ $b[1] ^ $a[2] ^ $b[2] ^ $a[3]; // a0 * 2*a1 + 3*a2 + a3
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$s[2][$c] = $a[0] ^ $a[1] ^ $b[2] ^ $a[3] ^ $b[3]; // a0 + a1 + 2*a2 + 3*a3
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$s[3][$c] = $a[0] ^ $b[0] ^ $a[1] ^ $a[2] ^ $b[3]; // 3*a0 + a1 + a2 + 2*a3
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}
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return $s;
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}
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/**
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* Generate Key Schedule from Cipher Key [§5.2].
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*
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* Perform key expansion on cipher key to generate a key schedule.
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*
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* @param key cipher key byte-array (16 bytes).
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* @return key schedule as 2D byte-array (Nr+1 x Nb bytes).
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*/
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public static function keyExpansion($key)
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{
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$Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
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$Nk = count($key) / 4; // key length (in words): 4/6/8 for 128/192/256-bit keys
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$Nr = $Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys
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$w = array();
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$temp = array();
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for ($i = 0; $i < $Nk; $i++) {
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$r = array($key[4 * $i], $key[4 * $i + 1], $key[4 * $i + 2], $key[4 * $i + 3]);
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$w[$i] = $r;
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}
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for ($i = $Nk; $i < ($Nb * ($Nr + 1)); $i++) {
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$w[$i] = array();
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for ($t = 0; $t < 4; $t++) $temp[$t] = $w[$i - 1][$t];
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if ($i % $Nk == 0) {
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$temp = self::subWord(self::rotWord($temp));
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for ($t = 0; $t < 4; $t++) $temp[$t] ^= self::$rCon[$i / $Nk][$t];
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} else if ($Nk > 6 && $i % $Nk == 4) {
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$temp = self::subWord($temp);
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}
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for ($t = 0; $t < 4; $t++) $w[$i][$t] = $w[$i - $Nk][$t] ^ $temp[$t];
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}
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return $w;
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}
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/**
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* Apply SBox to 4-byte word w.
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*/
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private static function subWord($w)
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{
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for ($i = 0; $i < 4; $i++) $w[$i] = self::$sBox[$w[$i]];
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return $w;
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}
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/**
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* Rotate 4-byte word w left by one byte.
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*/
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private static function rotWord($w)
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{
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$tmp = $w[0];
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for ($i = 0; $i < 3; $i++) $w[$i] = $w[$i + 1];
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$w[3] = $tmp;
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return $w;
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}
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// sBox is pre-computed multiplicative inverse in GF(2^8) used in subBytes and keyExpansion [§5.1.1]
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private static $sBox = array(
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0x63, 0x7c, 0x77, 0x7b, 0xf2, 0x6b, 0x6f, 0xc5, 0x30, 0x01, 0x67, 0x2b, 0xfe, 0xd7, 0xab, 0x76,
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0xca, 0x82, 0xc9, 0x7d, 0xfa, 0x59, 0x47, 0xf0, 0xad, 0xd4, 0xa2, 0xaf, 0x9c, 0xa4, 0x72, 0xc0,
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0xb7, 0xfd, 0x93, 0x26, 0x36, 0x3f, 0xf7, 0xcc, 0x34, 0xa5, 0xe5, 0xf1, 0x71, 0xd8, 0x31, 0x15,
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0x04, 0xc7, 0x23, 0xc3, 0x18, 0x96, 0x05, 0x9a, 0x07, 0x12, 0x80, 0xe2, 0xeb, 0x27, 0xb2, 0x75,
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0x09, 0x83, 0x2c, 0x1a, 0x1b, 0x6e, 0x5a, 0xa0, 0x52, 0x3b, 0xd6, 0xb3, 0x29, 0xe3, 0x2f, 0x84,
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0x53, 0xd1, 0x00, 0xed, 0x20, 0xfc, 0xb1, 0x5b, 0x6a, 0xcb, 0xbe, 0x39, 0x4a, 0x4c, 0x58, 0xcf,
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0xd0, 0xef, 0xaa, 0xfb, 0x43, 0x4d, 0x33, 0x85, 0x45, 0xf9, 0x02, 0x7f, 0x50, 0x3c, 0x9f, 0xa8,
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0x51, 0xa3, 0x40, 0x8f, 0x92, 0x9d, 0x38, 0xf5, 0xbc, 0xb6, 0xda, 0x21, 0x10, 0xff, 0xf3, 0xd2,
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0xcd, 0x0c, 0x13, 0xec, 0x5f, 0x97, 0x44, 0x17, 0xc4, 0xa7, 0x7e, 0x3d, 0x64, 0x5d, 0x19, 0x73,
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0x60, 0x81, 0x4f, 0xdc, 0x22, 0x2a, 0x90, 0x88, 0x46, 0xee, 0xb8, 0x14, 0xde, 0x5e, 0x0b, 0xdb,
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0xe0, 0x32, 0x3a, 0x0a, 0x49, 0x06, 0x24, 0x5c, 0xc2, 0xd3, 0xac, 0x62, 0x91, 0x95, 0xe4, 0x79,
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0xe7, 0xc8, 0x37, 0x6d, 0x8d, 0xd5, 0x4e, 0xa9, 0x6c, 0x56, 0xf4, 0xea, 0x65, 0x7a, 0xae, 0x08,
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0xba, 0x78, 0x25, 0x2e, 0x1c, 0xa6, 0xb4, 0xc6, 0xe8, 0xdd, 0x74, 0x1f, 0x4b, 0xbd, 0x8b, 0x8a,
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0x70, 0x3e, 0xb5, 0x66, 0x48, 0x03, 0xf6, 0x0e, 0x61, 0x35, 0x57, 0xb9, 0x86, 0xc1, 0x1d, 0x9e,
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0xe1, 0xf8, 0x98, 0x11, 0x69, 0xd9, 0x8e, 0x94, 0x9b, 0x1e, 0x87, 0xe9, 0xce, 0x55, 0x28, 0xdf,
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0x8c, 0xa1, 0x89, 0x0d, 0xbf, 0xe6, 0x42, 0x68, 0x41, 0x99, 0x2d, 0x0f, 0xb0, 0x54, 0xbb, 0x16);
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// rCon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
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private static $rCon = array(
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array(0x00, 0x00, 0x00, 0x00),
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array(0x01, 0x00, 0x00, 0x00),
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array(0x02, 0x00, 0x00, 0x00),
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array(0x04, 0x00, 0x00, 0x00),
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array(0x08, 0x00, 0x00, 0x00),
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array(0x10, 0x00, 0x00, 0x00),
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array(0x20, 0x00, 0x00, 0x00),
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array(0x40, 0x00, 0x00, 0x00),
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array(0x80, 0x00, 0x00, 0x00),
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array(0x1b, 0x00, 0x00, 0x00),
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array(0x36, 0x00, 0x00, 0x00));
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}
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* AES counter (CTR) mode implementation in PHP */
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/* (c) Chris Veness 2005-2014 www.movable-type.co.uk/scripts */
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/* Right of free use is granted for all commercial or non-commercial use under CC-BY licence. */
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/* No warranty of any form is offered. */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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Class AesCtr extends Aes
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{
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/**
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* Encrypt a text using AES encryption in Counter mode of operation
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* - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf
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*
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* Unicode multi-byte character safe
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*
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* @param plaintext source text to be encrypted
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* @param password the password to use to generate a key
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* @param nBits number of bits to be used in the key (128, 192, or 256)
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* @return encrypted text
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*/
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public static function encrypt($plaintext, $password, $nBits)
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{
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$blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
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if (!($nBits == 128 || $nBits == 192 || $nBits == 256)) return ''; // standard allows 128/192/256 bit keys
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// note PHP (5) gives us plaintext and password in UTF8 encoding!
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// use AES itself to encrypt password to get cipher key (using plain password as source for
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// key expansion) - gives us well encrypted key
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$nBytes = $nBits / 8; // no bytes in key
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$pwBytes = array();
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for ($i = 0; $i < $nBytes; $i++) $pwBytes[$i] = ord(substr($password, $i, 1)) & 0xff;
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$key = Aes::cipher($pwBytes, Aes::keyExpansion($pwBytes));
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$key = array_merge($key, array_slice($key, 0, $nBytes - 16)); // expand key to 16/24/32 bytes long
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// initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec,
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// [2-3] = random, [4-7] = seconds, giving guaranteed sub-ms uniqueness up to Feb 2106
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$counterBlock = array();
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$nonce = floor(microtime(true) * 1000); // timestamp: milliseconds since 1-Jan-1970
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$nonceMs = $nonce % 1000;
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$nonceSec = floor($nonce / 1000);
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$nonceRnd = floor(rand(0, 0xffff));
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for ($i = 0; $i < 2; $i++) $counterBlock[$i] = self::urs($nonceMs, $i * 8) & 0xff;
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for ($i = 0; $i < 2; $i++) $counterBlock[$i + 2] = self::urs($nonceRnd, $i * 8) & 0xff;
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for ($i = 0; $i < 4; $i++) $counterBlock[$i + 4] = self::urs($nonceSec, $i * 8) & 0xff;
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// and convert it to a string to go on the front of the ciphertext
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$ctrTxt = '';
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for ($i = 0; $i < 8; $i++) $ctrTxt .= chr($counterBlock[$i]);
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// generate key schedule - an expansion of the key into distinct Key Rounds for each round
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$keySchedule = Aes::keyExpansion($key);
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//print_r($keySchedule);
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$blockCount = ceil(strlen($plaintext) / $blockSize);
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$ciphertxt = array(); // ciphertext as array of strings
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for ($b = 0; $b < $blockCount; $b++) {
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// set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
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// done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB)
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for ($c = 0; $c < 4; $c++) $counterBlock[15 - $c] = self::urs($b, $c * 8) & 0xff;
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for ($c = 0; $c < 4; $c++) $counterBlock[15 - $c - 4] = self::urs($b / 0x100000000, $c * 8);
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$cipherCntr = Aes::cipher($counterBlock, $keySchedule); // -- encrypt counter block --
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// block size is reduced on final block
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$blockLength = $b < $blockCount - 1 ? $blockSize : (strlen($plaintext) - 1) % $blockSize + 1;
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$cipherByte = array();
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for ($i = 0; $i < $blockLength; $i++) { // -- xor plaintext with ciphered counter byte-by-byte --
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$cipherByte[$i] = $cipherCntr[$i] ^ ord(substr($plaintext, $b * $blockSize + $i, 1));
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$cipherByte[$i] = chr($cipherByte[$i]);
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}
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$ciphertxt[$b] = implode('', $cipherByte); // escape troublesome characters in ciphertext
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}
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// implode is more efficient than repeated string concatenation
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$ciphertext = $ctrTxt . implode('', $ciphertxt);
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$ciphertext = base64_encode($ciphertext);
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return $ciphertext;
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}
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/**
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* Decrypt a text encrypted by AES in counter mode of operation
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*
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* @param ciphertext source text to be decrypted
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* @param password the password to use to generate a key
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* @param nBits number of bits to be used in the key (128, 192, or 256)
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* @return decrypted text
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*/
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public static function decrypt($ciphertext, $password, $nBits)
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{
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$blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
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if (!($nBits == 128 || $nBits == 192 || $nBits == 256)) return ''; // standard allows 128/192/256 bit keys
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$ciphertext = base64_decode($ciphertext);
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// use AES to encrypt password (mirroring encrypt routine)
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$nBytes = $nBits / 8; // no bytes in key
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$pwBytes = array();
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for ($i = 0; $i < $nBytes; $i++) $pwBytes[$i] = ord(substr($password, $i, 1)) & 0xff;
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$key = Aes::cipher($pwBytes, Aes::keyExpansion($pwBytes));
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$key = array_merge($key, array_slice($key, 0, $nBytes - 16)); // expand key to 16/24/32 bytes long
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// recover nonce from 1st element of ciphertext
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$counterBlock = array();
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$ctrTxt = substr($ciphertext, 0, 8);
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for ($i = 0; $i < 8; $i++) $counterBlock[$i] = ord(substr($ctrTxt, $i, 1));
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// generate key schedule
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$keySchedule = Aes::keyExpansion($key);
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// separate ciphertext into blocks (skipping past initial 8 bytes)
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$nBlocks = ceil((strlen($ciphertext) - 8) / $blockSize);
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$ct = array();
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for ($b = 0; $b < $nBlocks; $b++) $ct[$b] = substr($ciphertext, 8 + $b * $blockSize, 16);
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$ciphertext = $ct; // ciphertext is now array of block-length strings
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// plaintext will get generated block-by-block into array of block-length strings
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$plaintxt = array();
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for ($b = 0; $b < $nBlocks; $b++) {
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// set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
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for ($c = 0; $c < 4; $c++) $counterBlock[15 - $c] = self::urs($b, $c * 8) & 0xff;
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for ($c = 0; $c < 4; $c++) $counterBlock[15 - $c - 4] = self::urs(($b + 1) / 0x100000000 - 1, $c * 8) & 0xff;
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$cipherCntr = Aes::cipher($counterBlock, $keySchedule); // encrypt counter block
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$plaintxtByte = array();
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for ($i = 0; $i < strlen($ciphertext[$b]); $i++) {
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// -- xor plaintext with ciphered counter byte-by-byte --
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$plaintxtByte[$i] = $cipherCntr[$i] ^ ord(substr($ciphertext[$b], $i, 1));
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$plaintxtByte[$i] = chr($plaintxtByte[$i]);
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}
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$plaintxt[$b] = implode('', $plaintxtByte);
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}
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// join array of blocks into single plaintext string
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$plaintext = implode('', $plaintxt);
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return $plaintext;
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}
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/*
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* Unsigned right shift function, since PHP has neither >>> operator nor unsigned ints
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*
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* @param a number to be shifted (32-bit integer)
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* @param b number of bits to shift a to the right (0..31)
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* @return a right-shifted and zero-filled by b bits
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*/
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private static function urs($a, $b)
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{
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$a &= 0xffffffff;
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$b &= 0x1f; // (bounds check)
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if ($a & 0x80000000 && $b > 0) { // if left-most bit set
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$a = ($a >> 1) & 0x7fffffff; // right-shift one bit & clear left-most bit
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$a = $a >> ($b - 1); // remaining right-shifts
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} else { // otherwise
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$a = ($a >> $b); // use normal right-shift
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}
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return $a;
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}
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}
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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?>
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