/**
 * 加密
 */
function lock_param($content,$key='')
{
    $content = $content . $key;
    $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-=+";
    $nh = rand(0, 64);
    $ch = $chars[$nh];
    $mdKey = md5($key . $ch);
    $mdKey = substr($mdKey, $nh % 8, $nh % 8 + 7);
    $content = base64_encode($content);
    $tmp = '';
    $i = 0;
    $j = 0;
    $k = 0;
    for ($i = 0; $i < strlen($content); $i++) {
        $k = $k == strlen($mdKey) ? 0 : $k;
        $j = ($nh + strpos($chars, $content[$i]) + ord($mdKey[$k++])) % 64;
        $tmp .= $chars[$j];
    }
    return urlencode(base64_encode($ch . $tmp));
}
/**
 * 解密
 */
function unlock_param($content,$key=''){
    $content = base64_decode(urldecode($content));
    $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-=+";
    $ch = $content[0];
    $nh = strpos($chars,$ch);
    $mdKey = md5($key.$ch);
    $mdKey = substr($mdKey,$nh%8, $nh%8+7);
    $content = substr($content,1);
    $tmp = '';
    $i=0;$j=0; $k = 0;
    for ($i=0; $i<strlen($content); $i++) {
        $k = $k == strlen($mdKey) ? 0 : $k;
        $j = strpos($chars,$content[$i])-$nh - ord($mdKey[$k++]);
        while ($j<0) $j+=64;
        $tmp .= $chars[$j];
    }
    return trim(base64_decode($tmp),$key);
}