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<?php
/*
* This class is also provided to a third party so any changes made in this class needs to be escalated for updating.
* */
class McryptUtil
{
private $key;
private $resMKript;
// private $twoWayHash; here we mean same text encrypts to same cipher every time you apply this method.
private $blockSize;
public function __construct($key, $algo)
{
// $this->key = $key;
// $this->resMKript = mcrypt_module_open($algo, '', 'cbc', '');
// $this->blockSize = mcrypt_enc_get_block_size($this->resMKript);
//NOTE: for twoWayHash, we can use mode 'ecb' with out static 'iv'. but the issue is 'ecb' is little slower than 'cbc'
//so we are using 'cbc' with static 'iv' for twoWayHashes
}
private function getIV()
{
$iv_size = mcrypt_enc_get_iv_size($this->resMKript);
$iv = '';
if(true)
{
for($i = 0; $i < $iv_size; $i++ )
{
$iv .= 'X';
}
}
else
{
$iv = mcrypt_create_iv (mcrypt_enc_get_iv_size($this->resMKript), mt_rand());
}
return $iv;
}
private function prependIVtoTheCipher($iv, $cipher)
{
return $iv.$cipher;
}
private function seperateCipherAndIV($cipher)
{
$data['iv'] = substr($cipher, 0, mcrypt_enc_get_iv_size($this->resMKript));
$data['cipher'] = substr($cipher, mcrypt_enc_get_iv_size($this->resMKript));
if($data['iv'] != $this->getIV())
{
$data['iv'] = $this->getIV();
$data['cipher'] = $cipher;
}
else
{
//my_var_dump("IV found in cipher");
}
return $data;
}
/**
* returns encrypted binary string.
* @param input data in binary string format
*/
private function encrypt($input)
{
//we need to create 'iv' everytime we try to encrypt data.
$iv = $this->getIV();
//before u do any encryption/decryption, you have to initialise module with key and iv
mcrypt_generic_init($this->resMKript, $this->key, $iv);
//now encrypt the data. before that, compress it to have the cipher compact.
$input= $this->_gzdeflate($input);
//padding with \c, c = number of bytes needed to complete the last block
//to ensure the same padding in node and php
$pad = $this->blockSize - (strlen($input) % $this->blockSize);
$input = $input . str_repeat(chr($pad), $pad);
$cipher = mcrypt_generic($this->resMKript,$input);
return $cipher;
}
/**
* returns decrypted data. remember to pass base64 decoded data.
*
* @param base64 decoded data
* @return plain text if successful
*/
private function decrypt($cipher)
{
//get the cipher and iv
$cipherData = $this->seperateCipherAndIV($cipher);
//initialise the module
mcrypt_generic_init($this->resMKript, $this->key, $cipherData['iv']);
//decrypt
$decryptedData = mdecrypt_generic($this->resMKript, $cipherData['cipher']);
//uncompress
$uncompressedData = $this->_gzinflate($decryptedData);
if($uncompressedData === false)
{
ExceptionFactory::throwCryptographyException('data could not be uncompressed');
}
return $uncompressedData;
}
private function _gzdeflate($input)
{
return gzdeflate($input);
}
private function _gzinflate($input)
{
return gzinflate($input);
}
public function encodeMime($input)
{
$enc = $this->encrypt($input);
$encodedString= base64_encode($enc);
$replaceArray = array('+'=>'-','/'=>'_');
return strtr($encodedString, $replaceArray);
}
public function decodeMime($mimeEncodedCipher)
{
$transArray = array('-'=>'+','_'=>'/');
$mimeEncodedCipher = strtr($mimeEncodedCipher, $transArray);
if( !isStringSet( $mimeEncodedCipher ) )
{
return null;
}
$binaryString = base64_decode($mimeEncodedCipher);
$decodedMime = $this->decrypt($binaryString);
echo $decodedMime;
return $decodedMime;
}
public function __destruct()
{
if($this->resMKript)
{
mcrypt_module_close($this->resMKript);
}
}
}
$o = 'b1S17e7MpHrNbIp37_Oqy1MpcchQ9FZb_FZ6z91JJnwzBcVPaS8C4cEMSbeL6NIeaaieG1pKB9v8Y0h7XnHE3Ot9BJpaJ5nDbhJ5cg3acY-ej8-E_YvSzyWaeqn7X7gOXLLQYKg1jyR87RqCxZU_wsHi7T4KyejlcB3tbpXPUOd1G1YAigRQudIhmIwCBsedlxRq5UvgyoYpELCa9QoRBScWq-CbMLBVpbguujNsHofC7AKaIuW5IK5h06-n97-HxPBKCIOIhFWH3fhbNJMD-bfzJgA48NlGK5hwCBvc2T-SLrN2g9eWimOwqpnyywxBrIBO2T9XS_36wVd5P6uspQdYyCrhY-nILlQvArmXGI2nPHxr8Ru65325Ioyzx_41Cwxx0-Ju6e4SHpSfphL5eTzK3btxqCbSOpkwFKiTD-EMF_rxzr1tdaGu0v8HESTYZtala9psUuHWx7BXcncMjlTWKbvmR_T409MWiZEfdoE2ZZYv_J8zEjBNuNpAXd3VwZHu641o4vS4_COnfsqe-6aTtsm1xYgltecJvlWJDKcv5jrYFybSMXp1u0Cw9nY1056ADGGHpZURFPGZ5JkxvziWc9O-gk5BNBwyaVjfI6MN8v3jcI3Gcz9aCLxKWa7WB5XvmRMhjrmv5yZpXOlk3mYrcSdmAZLvdvRyQmOf-04zVJoLQjTfAIig32OKzR_NTBKjBU_FVf7jWrGomE_N7i4HAerBXwSKgmhvYSwEQLbXIKTvMqdOxjlFp0vCqLglaAhZgeH82wEJGlN4vvuo0T0sw6PQsqXgNrS0h43pc1B58X-sSDZhbafrweyyv7N0Bc5Sp3QGY6o=';
$obj = new McryptUtil("key", "algo");
$decodedMime = $obj->decodeMime($o);
?>
