[加密] 试根据时间戳生成"时效密钥"来防止各种盗链 - Chinaunix

<?php
// hightman.050829: 根据时间戳记生成一定时效的动态密码.
class chrono_key {
var $_radix32; // 基本要素
var $_passwords; // 密钥列表, array()
var $_expiration; // 时间钥过期时间, 单位秒, 缺省1小时.
// 构造函数
function chrono_key($expiration = 3600, $passwd = "") {
// 基本属性初始化
$this->;_radix32 = "0123456789abcdefghijklmnopqrstuv";
$this->;_passwords = array();
if ($expiration >; 0) {
$this->;_expiration = $expiration;
}
if (!empty($passwd)) {
$this->;append_password($passwd);
}
}
// 设定过期时间
function set_expiration($sec) {
if ($sec >; 0) {
$this->;_expiration = $sec;
}
}
// 追加密钥
function append_password($str) {
if (!empty($str)) {
$rkey = $this->;_key($str);
if (!in_array($rkey, $this->;_passwords)) {
array_push($this->;_passwords, $rkey);
}
}
}
// 检查一个 key 是否过时 expired.
function key_check($str) {
// 先将字符串层层还源
if (!is_array($this->;_passwords) || count($this->;_passwords) == 0) {
trigger_error("至少需要设定一个加密密码, 请使用 append_password() 方法设定密码.", E_USER_ERROR);
}
$r_passwds = array_reverse($this->;_passwords);
foreach ($r_passwds as $tmp) {
$str = $this->;_str_crypto($str, $tmp);
}
$str = $this->;_str_decrypt($str);
// 转换成时间戳
$chrono = $this->;_str_chrono($str);
// 根据 expiration 判断是否超过
$cc = time() - $chrono;
// return value
if ($cc >; 0 && $cc < $this->;_expiration) return true;
else return false;
}
// 根据时间戳生成 key
function key_gen($chrono = 0) {
// 取得时间
$chrono = intval($chrono);
if ($chrono <= 0) {
$chrono = time();
}
// 转成字串
$str = $this->;_chrono_str($chrono);
// 加密
$str = $this->;_str_encrypt($str);
if (!is_array($this->;_passwords) || count($this->;_passwords) == 0) {
trigger_error("至少需要设定一个加密密码, 请使用 append_password() 方法设定密码.", E_USER_ERROR);
}
foreach ($this->;_passwords as $tmp) {
$str = $this->;_str_crypto($str, $tmp);
}
return $str;
}
// 将整型时间转化成标准字串
function _chrono_str($chrono) {
$str = "";
do {
$idx = ($chrono & 0x1f);
$str .= substr($this->;_radix32, $idx, 1);
$chrono >;>;= 5;
} while ($chrono >; 0);
return $str;
}
function _str_chrono($str) {
$chrono = 0;
$len = strlen($str);
if ($len >; 0) {
for ($i = 0; $i < $len; $i++) {
$char = substr($str, $i, 1);
$idx = $this->;_get_radix32_idx($char);
if ($idx < 0) break;
for ($j = $i; $j >; 0; $j--) {
$idx <<= 5;
}
$chrono += $idx;
}
}
return $chrono;
}
// 加密与解密函数
function _str_encrypt($str) {
$tmp_key = md5(rand(0, 0xffff));
$key_len = strlen($tmp_key);
$str_len = strlen($str);
$ret = "";
for ($i = 0; $i < $str_len; $i++) {
$j = $i % $key_len;
$p1 = $this->;_get_radix32_idx(substr($str, $i, 1));
$p2 = $this->;_get_radix32_idx(substr($tmp_key, $j, 1));
$p = $p1 ^ $p2;
$ret .= substr($this->;_radix32, $p2, 1);
$ret .= substr($this->;_radix32, $p, 1);
}
return $ret;
}
function _str_decrypt($str) {
$ret = "";
$str_len = strlen($str);
for ($i = 0; $i < $str_len; $i++) {
$md = substr($str, $i++, 1);
$ed = substr($str, $i, 1);
$p1 = $this->;_get_radix32_idx($md);
$p2 = $this->;_get_radix32_idx($ed);
$p = $p1 ^ $p2;
$ret .= substr($this->;_radix32, $p, 1);
}
return $ret;
}
function _str_crypto($str, $key) {
$str_len = strlen($str);
$key_len = strlen($key);
$ret = "";
for ($i = 0; $i < $str_len; $i++) {
$j = ($str_len - $i) % $key_len;
$p1 = $this->;_get_radix32_idx(substr($str, $i, 1));
$p2 = $this->;_get_radix32_idx(substr($key, $j, 1));
$p = $p1 ^ $p2;
$ret .= substr($this->;_radix32, $p, 1);
}
return $ret;
}
// 获取一个字符在 radix32 中的序号
function _get_radix32_idx($char) {
$idx = strpos($this->;_radix32, $char);
if (!is_int($idx)) $idx = -1;
return $idx;
}
// 生成标准密钥
function _key($str) {
return md5($str);
}
}
// 这部分是实例:
$ck = new chrono_key();
// 设定加密密码, 可以多组密码一起加密
$ck->;append_password("hightman");
$ck->;append_password("twomice");
// 设定密码的有效期, 缺省是 3600 秒即一小时
$ck->;set_expiration(30);
// 生成密钥 (可以选择性输入参数时间戳来)
$newkey = $ck->;key_gen();
// 检查提交上来的旧密钥是否还有效
if (isset($_GET['ckey'])) {
$str = "旧密钥: {$_GET['ckey']} 当前状态为 - ";
$str .= ($ck->;key_check($_GET['ckey']) ? "有效" : "过期") . "<br>;";
}
?>;
<title>;时效密钥的生成与检查</title>;
<h2>;时效密钥, 有效期: (30秒)</h2>;
<form method=get>;
<?=$str?>;
新密钥: <input type=text name=ckey value="<?=$newkey?>;">;
(每次刷新页面均生成新的密钥字串)
<br>;
<input type=submit value="检查这个密钥">;
<a href="3.phps">;查看源码</a>;
</form>;

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