PHP加密函数与解密函数详解

  
function encrypt_code($string, $expiry = 0, $key = '1234567890') {  
    $ckey_length = 1;  
    $key = md5($key ? $key : UC_KEY); //加密解密时这个是不变的  
    $keya = md5(substr($key, 0, 16)); //加密解密时这个是不变的  
    $keyb = md5(substr($key, 16, 16)); //加密解密时这个是不变的  
    $keyc = $ckey_length ?  substr(md5(microtime()), -$ckey_length) : '';  
    $crypTKEy = $keya . md5($keya . $keyc); //64  
    $key_length = strlen($cryptkey); //64  
   
    $string =sprintf('%010d', $expiry ? $expiry + time() : 0) . substr(md5($string . $keyb), 0, 16) . $string;  
    $string_length = strlen($string);  
   
    $result = '';  
    $box = range(0, 255);  
   
    $rndkey = array();  
    for ($i = 0; $i <= 255; $i++) { //字母表 64位后重复 数列 范围为48~122  
        $rndkey[$i] = ord($cryptkey[$i % $key_length]);  
    }  
   
    for ($j = $i = 0; $i < 256; $i++) { //这里是一个打乱算法  
        $j = ($j + $box[$i] + $rndkey[$i]) % 256;  
        $tmp = $box[$i];  
        $box[$i] = $box[$j];  
        $box[$j] = $tmp;  
    }  
    for ($a = $j = $i = 0; $i < $string_length; $i++) {  
        $result .= chr(ord($string[$i]) ^ ($box[$i]));  
       
    }  
     $str =  $keyc . str_replace('=', '', base64_encode($result));    
                //  $str =htmlentities($str, ENT_QUOTES, "UTF-8"); // curl 访问出错  
                  return $str ;  
}  
  
               
  
function encrypt_decode($string, $expiry = 0,$key = '1234567890') {    
    $ckey_length = 1;  
    $key = md5($key ? $key : UC_KEY); //加密解密时这个是不变的  
    $keya = md5(substr($key, 0, 16)); //加密解密时这个是不变的  
    $keyb = md5(substr($key, 16, 16)); //加密解密时这个是不变的  
                
    $keyc = $ckey_length ?  substr($string, 0, $ckey_length)   : '';  
  
    $cryptkey = $keya . md5($keya . $keyc); //64  
    $key_length = strlen($cryptkey); //64  
    $string = base64_decode(substr($string, $ckey_length)) ;  
               $string_length = strlen($string);  
    $result = '';  
    $box = range(0, 255);  
  
    $rndkey = array();  
    for ($i = 0; $i <= 255; $i++) { //字母表 64位后重复 数列 范围为48~122  
        $rndkey[$i] = ord($cryptkey[$i % $key_length]);  
    }  
    for ($j = $i = 0; $i < 256; $i++) { //这里是一个打乱算法  
        $j = ($j + $box[$i] + $rndkey[$i]) % 256;  
  
        $tmp = $box[$i];  
        $box[$i] = $box[$j];  
        $box[$j] = $tmp;  
    }  
    for($a = $j = $i = 0; $i < $string_length; $i++) {  
        $result .= chr(ord($string[$i]) ^ ($box[$i]));  
    }  
    if((substr($result, 0, 10) == 0 || substr($result, 0, 10) - time() > 0) && substr($result, 10, 16) == substr(md5(substr($result, 26) . $keyb), 0, 16)) {  
       return substr($result, 26);  
    }else{  
       return false;  
    }  
}