PHP example code for implementing a string encryption and decryption function

php Implement a string encryption and decryption function

Function Code as follows:

/*********************************************************************
  Function Name: encrypt
  Function Purpose: Encrypt or decrypt strings
  Usage Method:
  Encryption   :encrypt('str','E','nowamagic');
  Decryption   :encrypt('The encrypted string','D','nowamagic');
  Parameter Description:
  $string  : The string to be encrypted or decrypted
  $operation: Determines whether it is encryption or decryption: E: Encryption  D: Decryption
  $key   :The encryption key (cipher key);
http://www.cnblogs.com/roucheng/
*********************************************************************/
  function encrypt($string,$operation,$key='')
  {
    $key=md5($key);
    $key_length=strlen($key);
    $string=$operation=='D'?base64_decode($string):substr(md5($string.$key),0,8).$string;
    $string_length=strlen($string);
    $rndkey=$box=array();
    $result='';
    for($i=0;$i<=255;$i++)
    {
      $rndkey[$i]=ord($key[$i%$key_length]);
      $box[$i]=$i;
    }
    for($j=$i=0;$i<256;$i++)
    {
      $j=($j+$box[$i]+$rndkey[$i])%256;
      $tmp=$box[$i];
      $box[$i]=$box[$j];
      $box[$j]=$tmp;
    }
    for($a=$j=$i=0;$i<++)
    {
      $a=($a+1)%256;
      $j=($j+$box[$a])%256;
      $tmp=$box[$a];
      $box[$a]=$box[$j];
      $box[$j]=$tmp;
      $result.=chr(ord($string[$i])^($box[($box[$a+$box[$j])%256]);
    }
    
    {
      if(substr($result,0,85(substr($result,8).$key),0,8
      {
        return substr($result,8);
      }
      else
      {
        return'';
      }
    }
    else
    {
      return str_replace('=','',base64_encode($result));
    }
  }

Example Usage:

$id = 132;
$token = encrypt($id, 'E', 'a');
echo 'Encryption:'.encrypt($id, 'E', 'a');
 />
echo 'Decryption:'.encrypt($token, 'D', 'a');

Running Result:

Encryption: AYCnIibFlg3ViRs
Decryption:132

Thank you for reading, I hope it can help you. Thank you for your support of this site!