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encryption update

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1 parent 70eb4fb commit 905b8a604e9c25722f3375df4db48e8e4b37a1cd @danielkerr danielkerr committed Aug 8, 2012
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  1. +282 −1 upload/system/library/encryption.php
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283 upload/system/library/encryption.php
@@ -1,11 +1,292 @@
<?php
-class Encryption {
+class Encryption {
private $key;
+ // sBox is pre-computed multiplicative inverse in GF(2^8) used in subBytes and keyExpansion [§5.1.1]
+ 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);
+ // rCon is Round Constant used for the Key Expansion [1st col is 2^(r-1) in GF(2^8)] [§5.2]
+ private static $rCon = array(
+ array(0x00, 0x00, 0x00, 0x00),
+ array(0x01, 0x00, 0x00, 0x00),
+ array(0x02, 0x00, 0x00, 0x00),
+ array(0x04, 0x00, 0x00, 0x00),
+ array(0x08, 0x00, 0x00, 0x00),
+ array(0x10, 0x00, 0x00, 0x00),
+ array(0x20, 0x00, 0x00, 0x00),
+ array(0x40, 0x00, 0x00, 0x00),
+ array(0x80, 0x00, 0x00, 0x00),
+ array(0x1b, 0x00, 0x00, 0x00),
+ array(0x36, 0x00, 0x00, 0x00) );
+
function __construct($key) {
$this->key = $key;
}
+ public static function encrypt($plaintext, $password, $nBits = 128) {
+ $blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
+
+ if (!($nBits == 128 || $nBits == 192 || $nBits == 256)) return ''; // standard allows 128/192/256 bit keys
+ // note PHP (5) gives us plaintext and password in UTF8 encoding!
+
+ // use AES itself to encrypt password to get cipher key (using plain password as source for
+ // key expansion) - gives us well encrypted key
+ $nBytes = $nBits/8; // no bytes in key
+ $pwBytes = array();
+ for ($i=0; $i<$nBytes; $i++) $pwBytes[$i] = ord(substr($password,$i,1)) & 0xff;
+ $key = Aes::cipher($pwBytes, Aes::keyExpansion($pwBytes));
+ $key = array_merge($key, array_slice($key, 0, $nBytes-16)); // expand key to 16/24/32 bytes long
+
+ // initialise 1st 8 bytes of counter block with nonce (NIST SP800-38A §B.2): [0-1] = millisec,
+ // [2-3] = random, [4-7] = seconds, giving guaranteed sub-ms uniqueness up to Feb 2106
+ $counterBlock = array();
+ $nonce = floor(microtime(true)*1000); // timestamp: milliseconds since 1-Jan-1970
+ $nonceMs = $nonce%1000;
+ $nonceSec = floor($nonce/1000);
+ $nonceRnd = floor(rand(0, 0xffff));
+
+ for ($i=0; $i<2; $i++) $counterBlock[$i] = self::urs($nonceMs, $i*8) & 0xff;
+ for ($i=0; $i<2; $i++) $counterBlock[$i+2] = self::urs($nonceRnd, $i*8) & 0xff;
+ for ($i=0; $i<4; $i++) $counterBlock[$i+4] = self::urs($nonceSec, $i*8) & 0xff;
+
+ // and convert it to a string to go on the front of the ciphertext
+ $ctrTxt = '';
+ for ($i=0; $i<8; $i++) $ctrTxt .= chr($counterBlock[$i]);
+
+ // generate key schedule - an expansion of the key into distinct Key Rounds for each round
+ $keySchedule = Aes::keyExpansion($key);
+ //print_r($keySchedule);
+
+ $blockCount = ceil(strlen($plaintext)/$blockSize);
+ $ciphertxt = array(); // ciphertext as array of strings
+
+ for ($b=0; $b<$blockCount; $b++) {
+ // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
+ // done in two stages for 32-bit ops: using two words allows us to go past 2^32 blocks (68GB)
+ for ($c=0; $c<4; $c++) $counterBlock[15-$c] = self::urs($b, $c*8) & 0xff;
+ for ($c=0; $c<4; $c++) $counterBlock[15-$c-4] = self::urs($b/0x100000000, $c*8);
+
+ $cipherCntr = Aes::cipher($counterBlock, $keySchedule); // -- encrypt counter block --
+
+ // block size is reduced on final block
+ $blockLength = $b<$blockCount-1 ? $blockSize : (strlen($plaintext)-1)%$blockSize+1;
+ $cipherByte = array();
+
+ for ($i=0; $i<$blockLength; $i++) { // -- xor plaintext with ciphered counter byte-by-byte --
+ $cipherByte[$i] = $cipherCntr[$i] ^ ord(substr($plaintext, $b*$blockSize+$i, 1));
+ $cipherByte[$i] = chr($cipherByte[$i]);
+ }
+ $ciphertxt[$b] = implode('', $cipherByte); // escape troublesome characters in ciphertext
+ }
+
+ // implode is more efficient than repeated string concatenation
+ $ciphertext = $ctrTxt . implode('', $ciphertxt);
+ $ciphertext = base64_encode($ciphertext);
+ return $ciphertext;
+ }
+
+ public static function decrypt($ciphertext, $password, $nBits) {
+ $blockSize = 16; // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
+ if (!($nBits==128 || $nBits==192 || $nBits==256)) return ''; // standard allows 128/192/256 bit keys
+ $ciphertext = base64_decode($ciphertext);
+
+ // use AES to encrypt password (mirroring encrypt routine)
+ $nBytes = $nBits/8; // no bytes in key
+
+ $pwBytes = array();
+
+ for ($i=0; $i<$nBytes; $i++) $pwBytes[$i] = ord(substr($password,$i,1)) & 0xff;
+ $key = Aes::cipher($pwBytes, Aes::keyExpansion($pwBytes));
+ $key = array_merge($key, array_slice($key, 0, $nBytes-16)); // expand key to 16/24/32 bytes long
+
+ // recover nonce from 1st element of ciphertext
+ $counterBlock = array();
+ $ctrTxt = substr($ciphertext, 0, 8);
+ for ($i=0; $i<8; $i++) $counterBlock[$i] = ord(substr($ctrTxt,$i,1));
+
+ // generate key schedule
+ $keySchedule = Aes::keyExpansion($key);
+
+ // separate ciphertext into blocks (skipping past initial 8 bytes)
+ $nBlocks = ceil((strlen($ciphertext)-8) / $blockSize);
+ $ct = array();
+ for ($b=0; $b<$nBlocks; $b++) $ct[$b] = substr($ciphertext, 8+$b*$blockSize, 16);
+ $ciphertext = $ct; // ciphertext is now array of block-length strings
+
+ // plaintext will get generated block-by-block into array of block-length strings
+ $plaintxt = array();
+
+ for ($b=0; $b<$nBlocks; $b++) {
+ // set counter (block #) in last 8 bytes of counter block (leaving nonce in 1st 8 bytes)
+ for ($c=0; $c<4; $c++) $counterBlock[15-$c] = self::urs($b, $c*8) & 0xff;
+ for ($c=0; $c<4; $c++) $counterBlock[15-$c-4] = self::urs(($b+1)/0x100000000-1, $c*8) & 0xff;
+
+ $cipherCntr = Aes::cipher($counterBlock, $keySchedule); // encrypt counter block
+
+ $plaintxtByte = array();
+ for ($i=0; $i<strlen($ciphertext[$b]); $i++) {
+ // -- xor plaintext with ciphered counter byte-by-byte --
+ $plaintxtByte[$i] = $cipherCntr[$i] ^ ord(substr($ciphertext[$b],$i,1));
+ $plaintxtByte[$i] = chr($plaintxtByte[$i]);
+
+ }
+ $plaintxt[$b] = implode('', $plaintxtByte);
+ }
+
+ // join array of blocks into single plaintext string
+ $plaintext = implode('',$plaintxt);
+
+ return $plaintext;
+ }
+
+ private static function urs($a, $b) {
+ $a &= 0xffffffff; $b &= 0x1f; // (bounds check)
+ if ($a&0x80000000 && $b>0) { // if left-most bit set
+ $a = ($a>>1) & 0x7fffffff; // right-shift one bit & clear left-most bit
+ $a = $a >> ($b-1); // remaining right-shifts
+ } else { // otherwise
+ $a = ($a>>$b); // use normal right-shift
+ }
+ return $a;
+ }
+
+
+ public static function cipher($input, $w) { // main cipher function [§5.1]
+ $Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
+ $Nr = count($w) / $Nb - 1; // no of rounds: 10/12/14 for 128/192/256-bit keys
+
+ $state = array(); // initialise 4xNb byte-array 'state' with input [§3.4]
+
+ for ($i = 0; $i < 4 * $Nb; $i++) {
+ $state[$i % 4][floor($i / 4)] = $input[$i];
+ }
+
+ $state = self::addRoundKey($state, $w, 0, $Nb);
+
+ for ($round = 1; $round < $Nr; $round++) { // apply Nr rounds
+ $state = self::subBytes($state, $Nb);
+ $state = self::shiftRows($state, $Nb);
+ $state = self::mixColumns($state, $Nb);
+ $state = self::addRoundKey($state, $w, $round, $Nb);
+ }
+
+ $state = self::subBytes($state, $Nb);
+ $state = self::shiftRows($state, $Nb);
+ $state = self::addRoundKey($state, $w, $Nr, $Nb);
+
+ $output = array(4 * $Nb); // convert state to 1-d array before returning [§3.4]
+
+ for ($i = 0; $i < 4 * $Nb; $i++) {
+ $output[$i] = $state[$i % 4][floor($i / 4)];
+ }
+
+ return $output;
+ }
+
+
+ private static function addRoundKey($state, $w, $rnd, $Nb) { // xor Round Key into state S [§5.1.4]
+ for ($r=0; $r<4; $r++) {
+ for ($c=0; $c<$Nb; $c++) $state[$r][$c] ^= $w[$rnd*4+$c][$r];
+ }
+ return $state;
+ }
+
+ private static function subBytes($s, $Nb) { // apply SBox to state S [§5.1.1]
+ for ($r=0; $r<4; $r++) {
+ for ($c=0; $c<$Nb; $c++) $s[$r][$c] = self::$sBox[$s[$r][$c]];
+ }
+ return $s;
+ }
+
+ private static function shiftRows($s, $Nb) { // shift row r of state S left by r bytes [§5.1.2]
+ $t = array(4);
+ for ($r=1; $r<4; $r++) {
+ for ($c=0; $c<4; $c++) $t[$c] = $s[$r][($c+$r)%$Nb]; // shift into temp copy
+ for ($c=0; $c<4; $c++) $s[$r][$c] = $t[$c]; // and copy back
+ } // note that this will work for Nb=4,5,6, but not 7,8 (always 4 for AES):
+ return $s; // see fp.gladman.plus.com/cryptography_technology/rijndael/aes.spec.311.pdf
+ }
+
+ private static function mixColumns($s, $Nb) { // combine bytes of each col of state S [§5.1.3]
+ for ($c=0; $c<4; $c++) {
+ $a = array(4); // 'a' is a copy of the current column from 's'
+ $b = array(4); // 'b' is a•{02} in GF(2^8)
+ for ($i=0; $i<4; $i++) {
+ $a[$i] = $s[$i][$c];
+ $b[$i] = $s[$i][$c]&0x80 ? $s[$i][$c]<<1 ^ 0x011b : $s[$i][$c]<<1;
+ }
+ // a[n] ^ b[n] is a•{03} in GF(2^8)
+ $s[0][$c] = $b[0] ^ $a[1] ^ $b[1] ^ $a[2] ^ $a[3]; // 2*a0 + 3*a1 + a2 + a3
+ $s[1][$c] = $a[0] ^ $b[1] ^ $a[2] ^ $b[2] ^ $a[3]; // a0 * 2*a1 + 3*a2 + a3
+ $s[2][$c] = $a[0] ^ $a[1] ^ $b[2] ^ $a[3] ^ $b[3]; // a0 + a1 + 2*a2 + 3*a3
+ $s[3][$c] = $a[0] ^ $b[0] ^ $a[1] ^ $a[2] ^ $b[3]; // 3*a0 + a1 + a2 + 2*a3
+ }
+ return $s;
+ }
+
+ /**
+ * Key expansion for Rijndael cipher(): performs key expansion on cipher key
+ * to generate a key schedule
+ *
+ * @param key cipher key byte-array (16 bytes)
+ * @return key schedule as 2D byte-array (Nr+1 x Nb bytes)
+ */
+ public static function keyExpansion($key) { // generate Key Schedule from Cipher Key [§5.2]
+ $Nb = 4; // block size (in words): no of columns in state (fixed at 4 for AES)
+ $Nk = count($key)/4; // key length (in words): 4/6/8 for 128/192/256-bit keys
+ $Nr = $Nk + 6; // no of rounds: 10/12/14 for 128/192/256-bit keys
+
+ $w = array();
+ $temp = array();
+
+ for ($i=0; $i<$Nk; $i++) {
+ $r = array($key[4*$i], $key[4*$i+1], $key[4*$i+2], $key[4*$i+3]);
+ $w[$i] = $r;
+ }
+
+ for ($i=$Nk; $i<($Nb*($Nr+1)); $i++) {
+ $w[$i] = array();
+ for ($t=0; $t<4; $t++) $temp[$t] = $w[$i-1][$t];
+ if ($i % $Nk == 0) {
+ $temp = self::subWord(self::rotWord($temp));
+ for ($t=0; $t<4; $t++) $temp[$t] ^= self::$rCon[$i/$Nk][$t];
+ } else if ($Nk > 6 && $i%$Nk == 4) {
+ $temp = self::subWord($temp);
+ }
+ for ($t=0; $t<4; $t++) $w[$i][$t] = $w[$i-$Nk][$t] ^ $temp[$t];
+ }
+ return $w;
+ }
+
+ private static function subWord($w) { // apply SBox to 4-byte word w
+ for ($i=0; $i<4; $i++) $w[$i] = self::$sBox[$w[$i]];
+ return $w;
+ }
+
+ private static function rotWord($w) { // rotate 4-byte word w left by one byte
+ $tmp = $w[0];
+ for ($i=0; $i<3; $i++) $w[$i] = $w[$i+1];
+ $w[3] = $tmp;
+ return $w;
+ }
+
+
+
function encrypt($value) {
if (!$this->key) {
return $value;

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