357 lines
14 KiB
PHP
357 lines
14 KiB
PHP
<?php
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if (!defined('IN_XSS_PLATFORM')) {
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exit('Access Denied');
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}
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/*Aes.php
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*Date 2009/09/04
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*Auth song_qilin
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*Copyright Copyright (c) 2009 Kylix
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*/
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/* AES implementation in PHP (c) Chris Veness 2005-2008. Right of free use is granted for all */
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/* commercial or non-commercial use. No warranty of any form is offered. */
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/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - */
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/**
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* AES Cipher function: 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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function Cipher($input, $w) {// main Cipher function [§5.1]
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$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; $i++)
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$state[$i % 4][floor($i / 4)] = $input[$i];
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$state = AddRoundKey($state, $w, 0, $Nb);
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for ($round = 1; $round < $Nr; $round++) { // apply Nr rounds
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$state = SubBytes($state, $Nb);
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$state = ShiftRows($state, $Nb);
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$state = MixColumns($state, $Nb);
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$state = AddRoundKey($state, $w, $round, $Nb);
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}
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$state = SubBytes($state, $Nb);
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$state = ShiftRows($state, $Nb);
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$state = AddRoundKey($state, $w, $Nr, $Nb);
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$output = array(
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4 * $Nb
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); // convert state to 1-d array before returning [§3.4]
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for ($i = 0; $i < 4 * $Nb; $i++)
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$output[$i] = $state[$i % 4][floor($i / 4)];
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return $output;
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}
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function AddRoundKey($state, $w, $rnd, $Nb) {// xor Round Key into state S [§5.1.4]
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for ($r = 0; $r < 4; $r++) {
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for ($c = 0; $c < $Nb; $c++)
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$state[$r][$c] ^= $w[$rnd * 4 + $c][$r];
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}
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return $state;
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}
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function SubBytes($s, $Nb) {// apply SBox to state S [§5.1.1]
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global $Sbox; // PHP needs explicit declaration to access global variables!
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for ($r = 0; $r < 4; $r++) {
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for ($c = 0; $c < $Nb; $c++)
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$s[$r][$c] = $Sbox[$s[$r][$c]];
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}
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return $s;
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}
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function ShiftRows($s, $Nb) {// shift row r of state S left by r bytes [§5.1.2]
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$t = array(
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4
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);
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for ($r = 1; $r < 4; $r++) {
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for ($c = 0; $c < 4; $c++)
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$t[$c] = $s[$r][($c + $r) % $Nb]; // shift into temp copy
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for ($c = 0; $c < 4; $c++)
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$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 $s; // see fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
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}
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function MixColumns($s, $Nb) {// combine bytes of each col of state S [§5.1.3]
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for ($c = 0; $c < 4; $c++) {
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$a = array(
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4
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); // 'a' is a copy of the current column from 's'
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$b = array(
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4
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); // 'b' is a?{02} in GF(2^8)
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for ($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 $s;
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}
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/**
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* Key expansion for Rijndael Cipher(): performs key expansion on cipher key
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* to generate a key schedule
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*
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* @param key cipher key byte-array (16 bytes)
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* @return key schedule as 2D byte-array (Nr+1 x Nb bytes)
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*/
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function KeyExpansion($key) {// generate Key Schedule from Cipher Key [§5.2]
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global $Rcon; // PHP needs explicit declaration to access global variables!
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$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(
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$key[4 * $i],
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$key[4 * $i + 1],
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$key[4 * $i + 2],
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$key[4 * $i + 3]
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);
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$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; $t++)
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$temp[$t] = $w[$i - 1][$t];
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if ($i % $Nk == 0) {
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$temp = SubWord(RotWord($temp));
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for ($t = 0; $t < 4; $t++)
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$temp[$t] ^= $Rcon[$i / $Nk][$t];
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} else if ($Nk > 6 && $i % $Nk == 4) {
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$temp = SubWord($temp);
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}
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for ($t = 0; $t < 4; $t++)
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$w[$i][$t] = $w[$i - $Nk][$t] ^ $temp[$t];
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}
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return $w;
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}
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function SubWord($w) {// apply SBox to 4-byte word w
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global $Sbox; // PHP needs explicit declaration to access global variables!
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for ($i = 0; $i < 4; $i++)
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$w[$i] = $Sbox[$w[$i]];
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return $w;
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}
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function RotWord($w) {// rotate 4-byte word w left by one byte
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$w[4] = $w[0];
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for ($i = 0; $i < 4; $i++)
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$w[$i] = $w[$i + 1];
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return $w;
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}
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// Sbox is pre-computed multiplicative inverse in GF(2^8) used in SubBytes and KeyExpansion [§5.1.1]
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$Sbox = array(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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$Rcon = array( 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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* 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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function AESEncryptCtr($plaintext, $password = "blue-lotus", $nBits = 128) {
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$blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
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if (!($nBits == 128 || $nBits == 192 || $nBits == 256))
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return ''; // standard allows 128/192/256 bit keys
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// note PHP (5) gives us plaintext and password in UTF8 encoding!
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// use AES itself to encrypt password to get cipher key (using plain password as source for key
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// expansion) - gives us well encrypted key
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$nBytes = $nBits / 8; // no bytes in key
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$pwBytes = array();
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for ($i = 0; $i < $nBytes; $i++)
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$pwBytes[$i] = ord(substr($password, $i, 1)) & 0xff;
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$key = Cipher($pwBytes, KeyExpansion($pwBytes));
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$key = array_merge($key, array_slice($key, 0, $nBytes - 16)); // expand key to 16/24/32 bytes long
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// initialise counter block (NIST SP800-38A §B.2): millisecond time-stamp for nonce in
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// 1st 8 bytes, block counter in 2nd 8 bytes
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$counterBlock = array();
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$nonce = floor(microtime(true) * 1000); // timestamp: milliseconds since 1-Jan-1970
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$nonceSec = floor($nonce / 1000);
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$nonceMs = $nonce % 1000;
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// encode nonce with seconds in 1st 4 bytes, and (repeated) ms part filling 2nd 4 bytes
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for ($i = 0; $i < 4; $i++)
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$counterBlock[$i] = urs($nonceSec, $i * 8) & 0xff;
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for ($i = 0; $i < 4; $i++)
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$counterBlock[$i + 4] = $nonceMs & 0xff;
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// and convert it to a string to go on the front of the ciphertext
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$ctrTxt = '';
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for ($i = 0; $i < 8; $i++)
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$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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$keySchedule = KeyExpansion($key);
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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; $c++)
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$counterBlock[15 - $c] = urs($b, $c * 8) & 0xff;
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for ($c = 0; $c < 4; $c++)
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$counterBlock[15 - $c - 4] = urs($b / 0x100000000, $c * 8);
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$cipherCntr = 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 $ciphertext;
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}
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/**
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* Decrypt a text encrypted by AES in counter mode of operation
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*
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* @param ciphertext source text to be decrypted
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* @param password the password to use to generate a key
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* @param nBits number of bits to be used in the key (128, 192, or 256)
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* @return decrypted text
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*/
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function AESDecryptCtr($ciphertext, $password = "blue-lotus", $nBits = 128) {
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$blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
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if (!($nBits == 128 || $nBits == 192 || $nBits == 256))
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return ''; // standard allows 128/192/256 bit keys
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$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; $i++)
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$pwBytes[$i] = ord(substr($password, $i, 1)) & 0xff;
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$key = Cipher($pwBytes, KeyExpansion($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; $i++)
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$counterBlock[$i] = ord(substr($ctrTxt, $i, 1));
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// generate key schedule
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$keySchedule = 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; $b++)
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$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; $c++)
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$counterBlock[15 - $c] = urs($b, $c * 8) & 0xff;
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for ($c = 0; $c < 4; $c++)
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$counterBlock[15 - $c - 4] = urs(($b + 1) / 0x100000000 - 1, $c * 8) & 0xff;
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$cipherCntr = 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 $plaintext;
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}
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/*
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* Unsigned right shift function, since PHP has neither >>> operator nor unsigned ints
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*
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* @param a number to be shifted (32-bit integer)
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* @param b number of bits to shift a to the right (0..31)
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* @return a right-shifted and zero-filled by b bits
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*/
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function urs($a, $b) {
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$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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} |