[php]128비트 암호화 클래스 <StringEncrypter>

php용 128비트  암호화 클래스 StringEncrypter

 

php의 기본 암호화 기능도 있지만 더 보안성이 좋은 128비트 암호화 클래스를 소개 하고자 합니다.

MD5는 Hash의 충돌내성이 약하다고 알려져 있다고 합니다.

일본에서는 표준알고리즘에서 제외되었다고 하네요.

클래스와 선언 방법 그리고 간단한 사용 방법을 소스코드로 정리 해놓겠습니다.

 

 

key = md5 ($key, TRUE) ;
               $this->initialVector = md5 ($initialVector, TRUE) ;
          }

          /**
          * Encrypts a string.
          *
          * value: A string to encrypt. It must be a UTF-8 string.
          *        Null is regarded as an empty string.
          * return: An encrypted string.
          */
          public function encrypt ($value)
          {
               if ( is_null ($value) )
                    $value = "" ;

               if ( !is_string ($value) )
                    throw new Exception ("A non-string value can not be encrypted.") ;


               // Append padding
               $value = self::toPkcs7 ($value) ;

               // Encrypt the value.
               $output = mcrypt_encrypt (MCRYPT_RIJNDAEL_128, $this->key, $value, MCRYPT_MODE_CBC, $this->initialVector) ;

               // Return a base64 encoded string of the encrypted value.
               return base64_encode ($output) ;
          }

          /**
          * Decrypts a string which is encrypted with the same key and initial vector.
          *
          * value: A string to decrypt. It must be a string encrypted with the same key and initial vector.
          *        Null or an empty string is not allowed.
          * return: A decrypted string
          */
          public function decrypt ($value)
          {
               if ( !is_string ($value) or $value == "" )
                    throw new Exception ("The cipher string must be a non-empty string.") ;


               // Decode base64 encoding.
               $value = base64_decode ($value) ;

               // Decrypt the value.
               $output = mcrypt_decrypt (MCRYPT_RIJNDAEL_128, $this->key, $value, MCRYPT_MODE_CBC, $this->initialVector) ;

               // Strip padding and return.
               return self::fromPkcs7 ($output) ;
          }

          /**
          * Encodes data according to the PKCS7 padding algorithm.
          *
          * value: A string to pad. It must be a UTF-8 string.
          *        Null is regarded as an empty string.
          * return: A padded string
          */
          private static function toPkcs7 ($value)
          {
               if ( is_null ($value) )
                    $value = "" ;

               if ( !is_string ($value) )
                    throw new Exception ("A non-string value can not be used to pad.") ;


               // Get a number of bytes to pad.
               $padSize = self::STRENCRYPTER_BLOCK_SIZE - (strlen ($value) % self::STRENCRYPTER_BLOCK_SIZE) ;

               // Add padding and return.
               return $value . str_repeat (chr ($padSize), $padSize) ;
          }

          /**
          * Decodes data according to the PKCS7 padding algorithm.
          *
          * value: A string to strip. It must be an encoded string by PKCS7.
          *        Null or an empty string is not allowed.
          * return: A stripped string
          */
          private static function fromPkcs7 ($value)
          {
               if ( !is_string ($value) or $value == "" )
                    throw new Exception ("The string padded by PKCS7 must be a non-empty string.") ;

               $valueLen = strlen ($value) ;

               // The length of the string must be a multiple of block size.
               if ( $valueLen % self::STRENCRYPTER_BLOCK_SIZE > 0 )
                    throw new Exception ("The length of the string is not a multiple of block size.") ;


               // Get the padding size.
               $padSize = ord ($value{$valueLen - 1}) ;

               // The padding size must be a number greater than 0 and less equal than the block size.
               if ( ($padSize < 1) or ($padSize > self::STRENCRYPTER_BLOCK_SIZE) )
                    throw new Exception ("The padding size must be a number greater than 0 and less equal than the block size.") ;

               // Check padding.
               for ($i = 0; $i < $padSize; $i++)
               {
                    if ( ord ($value{$valueLen - $i - 1}) != $padSize )
                         throw new Exception ("A padded value is not valid.") ;
               }

               // Strip padding and return.
               return substr ($value, 0, $valueLen - $padSize) ;
          }
     }
?>

 

사용방법 입니다.

간단하게 클래스를 선언해서 함수를 호출 하여 사용하시면 됩니다.

     include $_SERVER[DOCUMENT_ROOT]."/StringEncrypter.php";
     define ("KEY", "TMT8250") ;
     define ("IV", "TMT8250") ;

     $encrypter = new StringEncrypter (KEY, IV) ;
    
     $enc_ssn = $encrypter->encrypt ($m_ss1 . $m_ss2) ;


     $m_pw     = $encrypter->encrypt($m_pw);