PHP加密解密的两种方法

一、利用md5和字符串处理函数

$key = "This is supposed to be a secret key !!!";  
function keyED($txt,$encrypt_key)  { 
 $encrypt_key = md5($encrypt_key); 
 $ctr=0;  $tmp = ""; 
 for ($i=0;$i
  if ($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;$i
 if ($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
 $md5 = substr($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 
";  
print "Encrypted text : $enc_text 
";  
print "Decrypted text : $dec_text 
"; 
 ?>

二、利用md5和base64_encode及json_encode函数

// 表单验证密匙$form_api_secret = 'Wuuh7ZL8n5gdhCFS2wtm6FmU/M0=';
$options = array();
$options['expiration'] = time()+600;
$options['save-key'] = '/{year}/{mon}/{day}/upload_{filename}{.suffix}';
$policy = base64_encode(json_encode($options));
$signature = md5($policy.'&'.$form_api_secret);
?>