Four useful PHP custom encryption functions (reversible/irreversible)

Sometimes in the project we need to use PHP to encrypt specific information, that is, to generate an encrypted string through the encryption algorithm. These encrypted strings can be decrypted through the decryption algorithm to facilitate the program to process the decrypted information. .

The most common applications are in user login and some API data exchange scenarios. The most common applications are in user login and some API data exchange scenarios. The principle of encryption and decryption is generally to use a certain encryption and decryption algorithm, add the key to the algorithm, and finally obtain the encryption and decryption results.

Without further ado, let’s get straight to the code.

1. The first reversible encryption function for ID can also be used for invitation codes and the like. The decrypted data is relatively simple

Example: lockcode(28)=》 000X unlockcode('000X')=》28

//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;
}

2. The second is the encryption function that I searched on the Internet. It is very easy to use, reversible encryption, and supports salt parameters.

Example:

encrypt('abcd','1234')=》nkiV93IfJ decrypt('nkiV93IfJ','1234')=》abcd

//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);  
}

Third, the third type is similar to the above, and also supports salt value parameters

Example: encrypt('abcd','1234')=》mZPHxw== decrypt( 'mZPHxw==','1234')=》abcd

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;  
}

4. This is the best one I have ever used, the encryption and decryption algorithm used in discuz

//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);

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