DNS Server Installation Step by Step Using CentOS 6.5

<?php
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES implementation in PHP (c) Chris Veness 2005-2011. Right of free use is granted for all    */
/*    commercial or non-commercial use under CC-BY licence. No warranty of any form is offered.   */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

class Aes {

/**
* AES Cipher function: encrypt 'input' with Rijndael algorithm
*
* @param input message as byte-array (16 bytes)
* @param w     key schedule as 2D byte-array (Nr+1 x Nb bytes) -
*              generated from the cipher key by keyExpansion()
* @return      ciphertext as byte-array (16 bytes)
*/
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
^ b
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;
}

// 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) );

}

/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
?>

<?php
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
/*  AES counter (CTR) mode implementation in PHP (c) Chris Veness 2005-2011. Right of free use is */
/*    granted for all commercial or non-commercial use under CC-BY licence. No warranty of any    */
/*    form is offered.                                                                            */
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */

class AesCtr extends Aes {

/**
* Encrypt a text using AES encryption in Counter mode of operation
*  - see http://csrc.nist.gov/publications/nistpubs/800-38a/sp800-38a.pdf *
* Unicode multi-byte character safe
*
* @param plaintext source text to be encrypted
* @param password  the password to use to generate a key
* @param nBits     number of bits to be used in the key (128, 192, or 256)
* @param keep      keep 1:each not change 0:each change(default)
* @return          encrypted text
*/
public static function encrypt($plaintext, $password, $nBits, $keep=0) {
$blockSize = 16;  // block size fixed at 16 bytes / 128 bits (Nb=4) for AES
if (!($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();

if($keep==0){
$nonce = floor(microtime(true)*1000);   // timestamp: milliseconds since 1-Jan-1970
$nonceMs = $nonce%1000;
$nonceSec = floor($nonce/1000);
$nonceRnd = floor(rand(0, 0xffff));
}else{
$nonce = 10000;
$nonceMs = $nonce%1000;
$nonceSec = floor($nonce/1000);
$nonceRnd = 10000;
}

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;
}

/**
* Decrypt a text encrypted by AES in counter mode of operation
*
* @param ciphertext source text to be decrypted
* @param password   the password to use to generate a key
* @param nBits      number of bits to be used in the key (128, 192, or 256)
* @return           decrypted text
*/
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;
}

/*
* Unsigned right shift function, since PHP has neither >>> operator nor unsigned ints
*
* @param a  number to be shifted (32-bit integer)
* @param b  number of bits to shift a to the right (0..31)
* @return   a right-shifted and zero-filled by b bits
*/
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;
}

}
/* - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -  */
?>

<?php
require 'aes.class.php';     // AES PHP implementation
require 'aesctr.class.php';  // AES Counter Mode implementation

echo 'each change<br>';

$mstr = AesCtr::encrypt('Hello World', 'key', 256);
echo "Encrypt String : $mstr<br />";

$dstr = AesCtr::decrypt($mstr, 'key', 256);
echo "Decrypt String : $dstr<br />";

echo 'each not change<br>';

$mstr = AesCtr::encrypt('Hello World', 'key', 256, 1);  // keep=1
echo "Encrypt String : $mstr<br />";

$dstr = AesCtr::decrypt($mstr, 'key', 256);
echo "Decrypt String : $dstr<br />";
?>

/* aes 256 encrypt
* @param String $ostr
* @param String $securekey
* @param String $type encrypt, decrypt
*/
function aes($ostr, $securekey, $type='encrypt'){
if($ostr==''){
return '';
}

$key = $securekey;
$iv = strrev($securekey);
$td = mcrypt_module_open('rijndael-256', '', 'ofb', '');
mcrypt_generic_init($td, $key, $iv);

$str = '';

switch($type){
case 'encrypt':
$str = base64_encode(mcrypt_generic($td, $ostr));
break;

case 'decrypt':
$str = mdecrypt_generic($td, base64_decode($ostr));
break;
}

mcrypt_generic_deinit($td);

return $str;
}

// Demo
$key = "fdipzone201314showmethemoney!@#$";
$str = "show me the money";

$ostr = aes($str, $key);
echo "String 1: $ostr<br />";

$dstr = aes($ostr, $key, 'decrypt');
echo "String 2: $dstr<br />";