标题：一段PHP加密与解密的代码
出处：大鹏天空™
时间：Tue, 23 Oct 2007 21:57:24 +0000
作者：zpgm
地址：http://www.rocsky.net/blog/read.php/311.htm

内容：
一段PHP加密与解密的代码

<?php 
$key = "This is supposed to be a secret key !!!"; 
function keyED($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 $tmp; 
} 
function encrypt($txt,$key) 
{ 
 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)); 
  $ctr++; 
 } 
 return keyED($tmp,$key); 
} 
function decrypt($txt,$key) 
{ 
 $txt = keyED($txt,$key); 
 $tmp = ""; 
 for ($i=0;$i<strlen($txt);$i++) 
 { 
  $md5 = substr($txt,$i,1); 
  $i++; 
  $tmp.= (substr($txt,$i,1) ^ $md5); 
 } 
 return $tmp; 
} 
$string = "Hello World !!!"; 
// encrypt $string, and store it in $enc_text 
$enc_text = encrypt($string,$key); 
// decrypt the encrypted text $enc_text, and store it in $dec_text 
$dec_text = decrypt($enc_text,$key); 
print "Original text : $string <Br>"; 
print "Encrypted text : $enc_text <Br>"; 
print "Decrypted text : $dec_text <Br>";
?>


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