Text File Decode

[Philips]

hello to everyone JavaScript Code convert Autoit code ?

 

 

JavaScript Code

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const fse = require('fs-extra');

module.exports = async function (file, out) {
  const fd = await fse.open(file, 'r');

  while (true) {
    let num = Buffer.allocUnsafe(4);

    if ((await fse.read(fd, num, 0, 4)).bytesRead != 4) break;

    num = num.readInt32LE(0);

    if (num > 0x8000) {
      throw new Exception('String is too long to decompile: ' + num);
    }

    let data = Buffer.allocUnsafe(num);

    if ((await fse.read(fd, data, 0, num)).bytesRead != num) break;

    let v = 0x816;

    for (let i = 0; i < num; i++) {
      let a = data[i];

      let z = (v & 0xff00) >>> 8;
      let b = (z ^ a) & 0xFF;
      v = (((((a + v) & 0xffff) * 0x6081) & 0xffff) + 0x1608) & 0xffff;

      data[i] = b;
    }

    if (out) {
      out(data);
    } else {
      process.stdout.write(data);
    }
  }

  await fse.close(fd);
}

 

[FrancescoDiMuro]

Hi @Philips, and welcome to the AutoIt forum
Maybe you missed the part

Quote

Usually asking for a script is not taken too well, within reason. Keep in mind that this is a support forum, so please acknowledge that. We are here to help you with your scripts, not to spoon-feed code to you.

in the Forum Etiquette.
By the way, start to take a look at File* and _File* functions in the Help file

[Philips]

3 hours ago, FrancescoDiMuro said:

Hi @Philips, and welcome to the AutoIt forum
Maybe you missed the part

in the Forum Etiquette.
By the way, start to take a look at File* and _File* functions in the Help file

not understand code :

 

let z = (v & 0xff00) >>> 8;
      let b = (z ^ a) & 0xFF;
      v = (((((a + v) & 0xffff) * 0x6081) & 0xffff) + 0x1608) & 0xffff;

[Davidowicza]

@Philips, Saying "I don't understand this:" isn't much help. Do you just not understand how to read javascript, do you not know why that script does those 3 lines or you do not know how to convert those 3 lines? Because we wouldn't know either until you tell us what the purpose of the script is and what you expect from the outcome.

[Earthshine]

looks like some bit shifting to begin with...

https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Bitwise_Operators

you got a lot to learn to understand that one kid... lol

One of my bosses loves bitmasking... lol, like we are in the old school days and don't have enough ram, you can load a boatload of flags into an integer... ahhh the old C days....

they use an integer (in binary) to store a bunch of flags for later use and use bit-masking to reveal what they want. this does save big on ram usage instead of one variable per flag... that's why we used to use it so much in the olden days... LOL

Edited October 23, 2018 by Earthshine

[Earthshine]

so anyway, they are filling a buffer with some data from a file they read, and then scanning it--looks like output goes to file or console, for what I don't know

Edited October 23, 2018 by Earthshine

[Earthshine]

https://www.autoitscript.com/autoit3/docs/functions/BitShift.htm

AutoIt has Bitshift and all the Bit functions you need, you might be able to code this

Edited October 23, 2018 by Earthshine

[Danp2]

Maybe it would help if you told us more about this javascript routine, such as --

• Where did it come from?
• What type of encryption is involved?
• Etc