PHP加密字符串函数（解密）

我们常用的php加密函数

function authcode($string, $operation = 'DECODE', $key = '', $expiry = 0){
	if($operation == 'DECODE') {
		$string = str_replace('[a]','+',$string);
		$string = str_replace('[b]','&',$string);
		$string = str_replace('[c]','/',$string);
	}

	$ckey_length = 4;
	$key = md5($key ? $key : 'livcmsencryption ');
	$keya = md5(substr($key, 0, 16));
	$keyb = md5(substr($key, 16, 16));
	$keyc = $ckey_length ? ($operation == 'DECODE' ? substr($string, 0, $ckey_length): substr(md5(microtime()), -$ckey_length)) : '';
	$cryptkey = $keya.md5($keya.$keyc);
	$key_length = strlen($cryptkey);

	$string = $operation == 'DECODE' ? base64_decode(substr($string, $ckey_length)) : 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++) {
		$rndkey[$i] = ord($cryptkey[$i % $key_length]);
	}

	for($j = $i = 0; $i < 256; $i++) {
		$j = ($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++) {
		$a = ($a + 1) % 256;
		$j = ($j + $box[$a]) % 256;
		$tmp = $box[$a];
		$box[$a] = $box[$j];
		$box[$j] = $tmp;
		$result .= chr(ord($string[$i]) ^ ($box[($box[$a] + $box[$j]) % 256]));
	}

	if($operation == 'DECODE') {
		if((substr($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 '';
		}
	} else {
		$ustr = $keyc.str_replace('=', '', base64_encode($result));
		$ustr = str_replace('+','[a]',$ustr);
		$ustr = str_replace('&','[b]',$ustr);
		$ustr = str_replace('/','[c]',$ustr);
		return $ustr;
	}

}

使用发放

$str = 'www.liqingbo.cn';
$res = authcode($str,'encode','liqingbo');
print_r($res);

$res = authcode($res,'DECODE','liqingbo');
print_r($res);

输出：

94begJWg2pTYHRsVPHz0AJOTTeQb9ovXGX2sCdtNrh[c]OWioMWt0tvoXjaSY
www.liqingbo.cn

如果秘钥liqingbo不一致，解密出来的是空