PHP implements AES256 encryption algorithm example, aes256 encryption algorithm example

The example in this article describes how PHP implements the AES256 encryption algorithm, which is a relatively common encryption algorithm. Share it with everyone for your reference. The details are as follows:

aes.class.php file is as follows:

<&#63;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' 
   $b = array(4); // 'b' is a&#8226;{02} in GF(2^8) 
   for ($i=0; $i<4; $i++) { 
    $a[$i] = $s[$i][$c]; 
    $b[$i] = $s[$i][$c]&0x80 &#63; $s[$i][$c]<<1 ^ 0x011b : $s[$i][$c]<<1; 
   } 
   // a[n] ^ b[n] is a&#8226;{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) );  
}  
&#63;>

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aesctr.class.php file is as follows:

<&#63;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 &#63; $blockSize : (strlen($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;  
 } 
}  
&#63;>

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Demo example program is as follows:

<&#63;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 />"; 
&#63;>

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Here is another introduction to another encryption and decryption method using PHP mcrypt:

/* 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 />";

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I hope this article will be helpful to everyone’s learning of PHP programming.

How to implement AES encryption and decryption in PHP

PHP loads the Mcrypt component php_mycrypt.dll/.so, which supports AES and 3DES encoding.
However, this module does not provide a padding method. You have to use PHP code to write padding methods such as PKCS7

Some questions about PHP encryption algorithm

1. The encryption algorithm is MCRYPT_RIJNDAEL_128. As for whether it is the AES you mentioned, it is hard to say. I personally think it shouldn't be. After all, the two don't look much alike.

2. There is no flaw in the code, but all encryption may be broken. The exhaustive method is just a time-consuming problem.
3. IV is used to initialize the algorithm. It also needs to be kept confidential.