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PHP function to decode data coded with JavaScript (Based on Base64)

I use the following JavaScript code to encode data. It uses scrambled modified base64 encoding.

Now I want to decode the data with PHP.

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<meta http-equiv="Content-Type" content="text/html; charset=iso-8859-1" /> 
<title>Scrambled Modified Base64</title> 
</head> 
<body> 

<pre>
<script type="text/javascript">
/* <![CDATA[ */

var keyStr = "rlc2WUQRb1iHLM7dGASyNtvOJx0Z5uK.fCepwIs6mjqB8XaghTFEPVDYonk349-_z";
function mb64(input) {
	var output ='';
	var chr1, chr2, chr3;
	var enc1, enc2, enc3, enc4;
	var i = 0;
	while (i < input.length) {
		chr1 = input.charCodeAt(i++);
		chr2 = input.charCodeAt(i++);
		chr3 = input.charCodeAt(i++);
 
		enc1 = chr1 >> 2;
		enc2 = ((chr1 & 3) << 4) | (chr2 >> 4);
		enc3 = ((chr2 & 15) << 2) | (chr3 >> 6);
		enc4 = chr3 & 63;
 
		if (isNaN(chr2)) {
			enc3 = enc4 = 64;
		} else if (isNaN(chr3)) {
			enc4 = 64;
		}
		output += keyStr.charAt(enc1) + keyStr.charAt(enc2) + keyStr.charAt(enc3) + keyStr.charAt(enc4);
   }
   return output;
}


function decode (input) {
		var output = "";
		var chr1, chr2, chr3;
		var enc1, enc2, enc3, enc4;
		var i = 0;
 
		input = input.replace(/[^A-Za-z0-9\+\/\=]/g, "");
 
		while (i < input.length) {
 
			enc1 = keyStr.indexOf(input.charAt(i++));
			enc2 = keyStr.indexOf(input.charAt(i++));
			enc3 = keyStr.indexOf(input.charAt(i++));
			enc4 = keyStr.indexOf(input.charAt(i++));
 
			chr1 = (enc1 << 2) | (enc2 >> 4);
			chr2 = ((enc2 & 15) << 4) | (enc3 >> 2);
			chr3 = ((enc3 & 3) << 6) | enc4;
 
			output = output + String.fromCharCode(chr1);
 
			if (enc3 != 64) {
				output = output + String.fromCharCode(chr2);
			}
			if (enc4 != 64) {
				output = output + String.fromCharCode(chr3);
			}
 
		}
		return output;
	}

document.write('<strong>Coded:</strong> ');
document.write(mb64('Hello World!'));
document.write('<br /><strong>Decoded:</strong> ');
document.write(decode('SQt8ZQ4ftD9FZQGC'));

/* ]]> */
</script>
</pre>

</body> 
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Steve Bink

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Ray Paseur

Just curious - why do you want to do this? I'm asking because there may be a better way to approach the issue, if we understand what the issue really is about. Thanks and regards, ~Ray