php加密解密函数

/**

* 加密函数

*

* @param string $txt 需要加密的字符串

* @param string $key 密钥

* @return string 返回加密结果

*/

function encrypt($txt, $key = ''){

if (emptyempty($txt)) return $txt;

if (emptyempty($key)) $key = md5(MD5_KEY);

$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.";

$ikey ="-x6g6ZWm2G9g_vr0Bo.pOq3kRIxsZ6rm";

$nh1 = rand(0,64);

$nh2 = rand(0,64);

$nh3 = rand(0,64);

$ch1 = $chars{$nh1};

$ch2 = $chars{$nh2};

$ch3 = $chars{$nh3};

$nhnum = $nh1 + $nh2 + $nh3;

$knum = 0;$i = 0;

while(isset($key{$i})) $knum +=ord($key{$i++});

$mdKey = substr(md5(md5(md5($key.$ch1).$ch2.$ikey).$ch3),$nhnum%8,$knum%8 + 16);

$txt = base64_encode(time().'_'.$txt);

$txt = str_replace(array('+','/','='),array('-','_','.'),$txt);

$tmp = '';

$j=0;$k = 0;

$tlen = strlen($txt);

$klen = strlen($mdKey);

for ($i=0; $i<$tlen; $i++) {

$k = $k == $klen ? 0 : $k;

$j = ($nhnum+strpos($chars,$txt{$i})+ord($mdKey{$k++}))%64;

$tmp .= $chars{$j};

}

$tmplen = strlen($tmp);

$tmp = substr_replace($tmp,$ch3,$nh2 % ++$tmplen,0);

$tmp = substr_replace($tmp,$ch2,$nh1 % ++$tmplen,0);

$tmp = substr_replace($tmp,$ch1,$knum % ++$tmplen,0);

return $tmp;

}

/**

* 解密函数

*

* @param string $txt 需要解密的字符串

* @param string $key 密匙

* @return string 字符串类型的返回结果

*/

function decrypt($txt, $key = '', $ttl = 0){

if (emptyempty($txt)) return $txt;

if (emptyempty($key)) $key = md5(MD5_KEY);

$chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789-_.";

$ikey ="-x6g6ZWm2G9g_vr0Bo.pOq3kRIxsZ6rm";

$knum = 0;$i = 0;

$tlen = @strlen($txt);

while(isset($key{$i})) $knum +=ord($key{$i++});

$ch1 = @$txt{$knum % $tlen};

$nh1 = strpos($chars,$ch1);

$txt = @substr_replace($txt,'',$knum % $tlen--,1);

$ch2 = @$txt{$nh1 % $tlen};

$nh2 = @strpos($chars,$ch2);

$txt = @substr_replace($txt,'',$nh1 % $tlen--,1);

$ch3 = @$txt{$nh2 % $tlen};

$nh3 = @strpos($chars,$ch3);

$txt = @substr_replace($txt,'',$nh2 % $tlen--,1);

$nhnum = $nh1 + $nh2 + $nh3;

$mdKey = substr(md5(md5(md5($key.$ch1).$ch2.$ikey).$ch3),$nhnum % 8,$knum % 8 + 16);

$tmp = '';

$j=0; $k = 0;

$tlen = @strlen($txt);

$klen = @strlen($mdKey);

for ($i=0; $i<$tlen; $i++) {

$k = $k == $klen ? 0 : $k;

$j = strpos($chars,$txt{$i})-$nhnum - ord($mdKey{$k++});

while ($j<0) $j+=64;

$tmp .= $chars{$j};

}

$tmp = str_replace(array('-','_','.'),array('+','/','='),$tmp);

$tmp = trim(base64_decode($tmp));

if (preg_match("/d{10}_/s",substr($tmp,0,11))){

if ($ttl > 0 && (time() - substr($tmp,0,11) > $ttl)){

$tmp = null;

}else{

$tmp = substr($tmp,11);

}

}

return $tmp;

}