About encryption and decryption Base64 and URL and Hex Encoding and Decoding

Author：Eve Cole Update Time：2025-02-26 01:00:03

Today I wanted to change the style of the Discuz forum. Unexpectedly, after downloading the style file, I found that it was encrypted with Base64.

Xiao Lin recommended a decrypted page, and the extracted code is as follows:

Copy the code code as follows:

<!DOCTYPE html PUBLIC -//W3C//DTD HTML 4.01 Transitional//EN>

<html>

<head>

<title>Base64 and URL and Hex Encoding and Decoding</title>

<!--

function urlDecode(str){

str=str.replace(new RegExp('//+','g'),' ');

return unescape(str);

}

function urlEncode(str){

str=escape(str);

str=str.replace(new RegExp('//+','g'),'%2B');

return str.replace(new RegExp('%20','g'),'+');

}

var END_OF_INPUT = -1;

var base64Chars = new Array(

'A','B','C','D','E','F','G','H',

'I','J','K','L','M','N','O','P',

'Q','R','S','T','U','V','W','X',

'Y','Z','a','b','c','d','e','f',

'g','h','i','j','k','l','m','n',

'o','p','q','r','s','t','u','v',

'w','x','y','z','0','1','2','3',

'4','5','6','7','8','9','+','/'

);

var reverseBase64Chars = new Array();

for (var i=0; i < base64Chars.length; i++){

reverseBase64Chars[base64Chars[i]] = i;

}

var base64Str;

var base64Count;

function setBase64Str(str){

base64Str = str;

base64Count = 0;

}

function readBase64(){

if (!base64Str) return END_OF_INPUT;

if (base64Count >= base64Str.length) return END_OF_INPUT;

var c = base64Str.charCodeAt(base64Count) & 0xff;

base64Count++;

return c;

}

function encodeBase64(str){

setBase64Str(str);

var result = '';

var inBuffer = new Array(3);

var lineCount = 0;

var done = false;

while (!done && (inBuffer[0] = readBase64()) != END_OF_INPUT){

inBuffer[1] = readBase64();

inBuffer[2] = readBase64();

result += (base64Chars[ inBuffer[0] >> 2 ]);

if (inBuffer[1] != END_OF_INPUT){

result += (base64Chars [(( inBuffer[0] << 4 ) & 0x30) | (inBuffer[1] >> 4) ]);

if (inBuffer[2] != END_OF_INPUT){

result += (base64Chars [((inBuffer[1] << 2) & 0x3c) | (inBuffer[2] >> 6) ]);

result += (base64Chars [inBuffer[2] & 0x3F]);

} else {

result += (base64Chars [((inBuffer[1] << 2) & 0x3c)]);

result += ('=');

done = true;

}

} else {

result += (base64Chars [(( inBuffer[0] << 4 ) & 0x30)]);

result += ('=');

done = true;

}

lineCount += 4;

if (lineCount >= 76){

result += ('/n');

lineCount = 0;

}

return result;

}

function readReverseBase64(){

if (!base64Str) return END_OF_INPUT;

while (true){

if (base64Count >= base64Str.length) return END_OF_INPUT;

var nextCharacter = base64Str.charAt(base64Count);

base64Count++;

if (reverseBase64Chars[nextCharacter]){

return reverseBase64Chars[nextCharacter];

}

if (nextCharacter == 'A') return 0;

}

return END_OF_INPUT;

}

function ntos(n){

n=n.toString(16);

if (n.length == 1) n=0+n;

n=%+n;

return unescape(n);

}

function decodeBase64(str){

setBase64Str(str);

var result = ;

var inBuffer = new Array(4);

var done = false;

while (!done && (inBuffer[0] = readReverseBase64()) != END_OF_INPUT

&& (inBuffer[1] = readReverseBase64()) != END_OF_INPUT){

inBuffer[2] = readReverseBase64();

inBuffer[3] = readReverseBase64();

result += ntos((((inBuffer[0] << 2) & 0xff)| inBuffer[1] >> 4));

if (inBuffer[2] != END_OF_INPUT){

result += ntos((((inBuffer[1] << 4) & 0xff)| inBuffer[2] >> 2));

if (inBuffer[3] != END_OF_INPUT){

result += ntos((((inBuffer[2] << 6) & 0xff) | inBuffer[3]));

} else {

done = true;

}

} else {

done = true;

}

return result;

}

var digitArray = new Array('0','1','2','3','4','5','6','7','8','9','a', 'b','c','d','e','f');

function toHex(n){

var result = ''

var start = true;

for (var i=32; i>0;){

i-=4;

var digit = (n>>i) & 0xf;

if (!start || digit != 0){

start = false;

result += digitArray[digit];

}

return (result==''?'0':result);

}

function pad(str, len, pad){

var result = str;

for (var i=str.length; i<len; i++){

result = pad + result;

}

return result;

}

function encodeHex(str){

var result = ;

for (var i=0; i<str.length; i++){

result += pad(toHex(str.charCodeAt(i)&0xff),2,'0');

}

return result;

}

function decodeHex(str){

str = str.replace(new RegExp(s/[^0-9a-zA-Z]//g));

var result = ;

var nextchar = ;

for (var i=0; i<str.length; i++){

nextchar += str.charAt(i);

if (nextchar.length == 2){

result += ntos(eval('0x'+nextchar));

nextchar = ;

}

return result;

}

//--></script>

</head>

<body>

<textarea name=text style='width:100%;height:75%;' onfocus='if (this.value==Enter text to encode or decode here.){this.value=;}'>Enter text to encode or decode here.</textarea>

<table>

</td><td align=center>

URL

</td><td align=center>

</td></tr>

</td><td align=center>

Base 64

</td><td align=center>

</td></tr>

</td><td align=center>

Hex

</td><td align=center>

</td></tr>

</td><td align=center>

</td><td align=center>

</td></tr>

</table>

</form>

<hr>

Base64 encode/decode was ported from a <a href=http://ostermiller.org/utils/Base64.html>Java Base64 encoder/decoder</a>.<br>

Base64 encode/decode was ported to <a href=http://ostermiller.org/base64_actionscript.html>Macromedia Actionscript</a>.<br>

<h3>License</h3>

<p>This program is free software; you can redistribute it and/or modify it

under the terms of the GNU General Public License as published by the Free

Software Foundation; either version 2 of the License, or (at your option)

any later version.</p>

<p>This program is distributed in the hope that it will be useful,

but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY

or FITNESS FOR A PARTICULAR PURPOSE. See the

<a href=http://www.gnu.org/copyleft/gpl.html>GNU

General Public License</a> for more details.</p>

</body>

</html>