Simple cryptography: decryption algorithm needed in PHP

问题

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.

回答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

回答2:

Assuming the text is stored in $string, try this:

$vars = array(
    'AA' => 'A',
    'BB' => 'B',
    'CC' => 'C',
    'A1' => '1',
    'B2' => '2',
    'C3' => '3',
);

$string = str_replace(array_keys($vars), array_values($vars), $string);

Also heed the warning from PHP's docs on str_replace:

Replacement order gotcha

Because str_replace() replaces left to right, it might replace a previously inserted value when doing multiple replacements. See also the examples in this document.

回答3:

Try this

$str = 'AA,BB,CC,A1,B2,C3';
$arr = explode(',', $str);
$newStr = '';
foreach($arr as $val){
    $newStr .= substr($val,1,1);
}
echo $newStr;

Output

ABC123

回答4:

If you don't want to change your strings try this

$count = 0;
while(true){
    $var = "var".++$count;
    if($$var){
        $$var = ${$var}[1];
    }
    else break;
}

来源：https://stackoverflow.com/questions/25555011/simple-cryptography-decryption-algorithm-needed-in-php

标签

php

cryptography