Implementation tips for PHP encryption and decryption

This article mainly introduces the PHP encryption and decryption of the relevant implementation skills, interested in the reference of friends, hope to help you.

Specific as follows:

<?phpclass ender{private $enkey;//encryption decryption with the key private $rep _char= ' # ';  Replace the = in the encrypted base64 string, because = is forbidden in some cases,//this can be replaced with an allowable character.    The construction parameter is the key public function __construct ($key = ") {if (! $key) {$this->enkey= $key;  }}//Set key http://blog.ddian.cn public function Set_key ($key) {$this->enkey= $key;   } Private Function KeyED ($txt, $encrypt _key) {$encrypt _key = MD5 ($encrypt _key);   $ctr = 0;   $tmp = "";   for ($i =0; $i <strlen ($txt); $i + +) {if ($ctr ==strlen ($encrypt _key)) $ctr = 0;   $tmp. = substr ($txt, $i, 1) ^ substr ($encrypt _key, $ctr, 1);   $ctr + +;  } return $tmp;  }//Encrypt string public function encrypt ($txt, $key = ") {if (! $key) {$key = $this->enkey;   } srand (Double) microtime () *1000000);   $encrypt _key = MD5 (rand (0,32000));   $ctr = 0;   $tmp = "";   for ($i =0; $i <strlen ($txt); $i + +) {if ($ctr ==strlen ($encrypt _key)) $ctr = 0;   $tmp. = substr ($encrypt _key, $ctr, 1).   (Substr ($txt, $i, 1) ^ substr ($encrypt _key, $ctr, 1));   $ctr + +; } $r =base64_encode ($this-&Gt;keyed ($tmp, $key));  $r =str_replace (' = ', $this->rep_char, $r);   return $r;  }//Decrypt the string public function decrypt ($txt, $key = ') {$txt =str_replace ($this->rep_char, ' = ', $txt);  $txt =base64_decode ($txt);  if (! $key) {$key = $this->enkey;   } $txt = $this->keyed ($txt, $key);   $tmp = "";   for ($i =0; $i <strlen ($txt); $i + +) {$MD 5 = substr ($txt, $i, 1);   $i + +;   $tmp. = (substr ($txt, $i, 1) ^ $md 5);   } return $tmp; }}

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