简单加密：PHP中需要的解密算法

Question

I'm working the webpage that I have some text like this:
AA,BB,CC,A1,B2,C3
And I want some code to replace the the word (like AA) to the string that saved in variable for example this is my php variable:

<?php
    $var1 = "A"; //For AA
    $var2 = "B"; //For BB 
    $var3 = "C"; //For CC
    $var4 = "1"; //For A1
    $var5 = "2"; //For B2
    $var6 = "3"; //For C3
?>

And the text AA,BB,CC,A1,B2,B3 will be like this:
ABC123
How can I do this with php?

In summery I need a decryption algorithm for a cypher text of AA,BB,CC,A1,B2,C3 to be converted as plan text of ABC123.

Answer 1

Full working script with sample encryption catalog given here.

<?php
$encript = array(
'a'=>'GG', 
'b'=>'HH',  
'c'=>'II',

'A'=>'DD',  
'B'=>'EE',
'B'=>'FF',

'1'=>'AA', 
'2'=>'BB',
'3'=>'CC');


function decrypt($str,$encript)
{
    $decript = array_flip($encript);
    $str_arr = explode(",",$str);
    $dec = "";
    foreach($str_arr as $val)
    {
        $dec .= $decript[strtoupper(trim($val))];
    }
    return $dec;
}

function encrypt($str,$encript)
{ 
    $str_arr = str_split($str);
    $dec = "";
    foreach($str_arr as $val)
    {
        $dec .= $encript[trim($val)].",";
    }
    return $dec;
}


$cypher = "AA,BB,DD,CC,EE,FF,GG,HH";
$text = "Ab1Ca";

echo decrypt($cypher,$encript);
echo "<br/>";
echo encrypt($text,$encript);
?>

• First we have to create the mapping for each character as associative array.
• In decrypt function first we have to flip the array.
• Then have to loop through each encoding string and build the real text from flipped array.
• In encryption split the string as single letter array.
• Loop through the array and build encryption using the mapping array.

The working out put available at following url: http://sugunan.net/demo/str1.php