四种好用的PHP自定义加密函数（可逆/不可逆）

//加密函数
function lockcode($code) {
    static $source_string = 'E5FCDG3HQA4B1NOPIJ2RSTUV67MWX89KLYZ';
    $num = $code;
    $code = '';
    while ( $num > 0) {
        $mod = $num % 35;
        $num = ($num - $mod) / 35;
        $code = $source_string[$mod].$code;
    }
    if(empty($code[3]))
        $code = str_pad($code,4,'0',STR_PAD_LEFT);
    return $code;
}
//解密函数
function unlockcode($code) {
    static $source_string = 'E5FCDG3HQA4B1NOPIJ2RSTUV67MWX89KLYZ';
    if (strrpos($code, '0') !== false)
        $code = substr($code, strrpos($code, '0')+1);
    $len = strlen($code);
    $code = strrev($code);
    $num = 0;
    for ($i=0; $i < $len; $i++) {
        $num += strpos($source_string, $code[$i]) * pow(35, $i);
    }
    return $num;
}

//加密函数  
function encrypt($data,$key='CHENI'){  
    $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";  
    $nh = rand(0,64);  
    $ch = $chars[$nh];  
    $mdKey = md5($key.$ch);  
    $mdKey = substr($mdKey,$nh%8, $nh%8+7);  
    $data= base64_encode($data);  
    $tmp = '';  
    $i=0;$j=0;$k = 0;  
    for ($i=0; $i<strlen($data); $i++) {  
        $k = $k == strlen($mdKey) ? 0 : $k;  
        $j = ($nh+strpos($chars,$data[$i])+ord($mdKey[$k++]))%64;  
        $tmp .= $chars[$j];  
    }  
    return urlencode($ch.$tmp);  
}
//解密函数  
function decrypt($data,$key=&#39;CHENI&#39;){
    $txt = urldecode($data);  
    $chars = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789";  
    $ch = $txt[0];  
    $nh = strpos($chars,$ch);  
    $mdKey = md5($key.$ch);  
    $mdKey = substr($mdKey,$nh%8, $nh%8+7);  
    $txt = substr($txt,1);  
    $tmp = &#39;&#39;;  
    $i=0;$j=0; $k = 0;  
    for ($i=0; $i<strlen($txt); $i++) {  
        $k = $k == strlen($mdKey) ? 0 : $k;  
        $j = strpos($chars,$txt[$i])-$nh - ord($mdKey[$k++]);  
        while ($j<0) $j+=64;  
        $tmp .= $chars[$j];  
    }  
    return base64_decode($tmp);  
}

function encrypt($data, $key)  {  
    $char="";
    $str="";
    $key    =   md5($key);  
    $x      =   0;  
    $len    =   strlen($data);  
    $l      =   strlen($key);  
    for ($i = 0; $i < $len; $i++) {  
        if ($x == $l) { $x = 0; }  
        $char .= $key{$x};  
        $x++;  
    }  
    for ($i = 0; $i < $len; $i++){  
        $str .= chr(ord($data{$i}) + (ord($char{$i})) % 256);  
    }  
    return base64_encode($str);  
}  
function decrypt($data, $key) {  
    $key = md5($key);  
    $x = 0;  
    $data = base64_decode($data);  
    $len = strlen($data);  
    $l = strlen($key);  
    for ($i = 0; $i < $len; $i++) {  
        if ($x == $l){ $x = 0;}  
        $char .= substr($key, $x, 1);  
        $x++;  
    }  
    for ($i = 0; $i < $len; $i++){  
        if (ord(substr($data, $i, 1)) < ord(substr($char, $i, 1))){  
            $str .= chr((ord(substr($data, $i, 1)) + 256) - ord(substr($char, $i, 1)));  
        }else{  
            $str .= chr(ord(substr($data, $i, 1)) - ord(substr($char, $i, 1)));  
        }  
    }  
    return $str;  
}

//加密算法
    function authcode($string,$key='',$operation=false,$expiry=0){
        $ckey_length = 4;
        $key = md5($key ? $key : DEFAULT_KEYS);
        $keya = md5(substr($key, 0, 16));
        $keyb = md5(substr($key, 16, 16));
        $keyc = $ckey_length ? ($operation? substr($string, 0, $ckey_length):substr(md5(microtime()), -$ckey_length)) : '';
        $cryptkey = $keya.md5($keya.$keyc);
        $key_length = strlen($cryptkey);
        $string = $operation? base64_decode(substr($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($operation) {
            if((substr($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 &#39;&#39;;
            }
        } else {
            return $keyc.str_replace(&#39;=&#39;, &#39;&#39;, base64_encode($result));
        }
    }
    echo authcode(&#39;123456&#39;,&#39;key&#39;);
    echo &#39;<br>&#39;;
    echo authcode(&#39;7d49kn9k07uSBZvha8as+/qm4UoLfpy88PFg12glPeDtlzc&#39;,&#39;key&#39;,true);