resedit-js

resedit-js is a library that manipulates resouces contained by Windows Executable files. All implementations are written in JavaScript (TypeScript), without using any native binaries. resedit-js works in both Node.js environment and Web environment.

This library is not tested well for modifying and/or signing executables yet. Please be careful with the emitted binaries.

To use from command line, resedit-js-cli is suitable.

The demo page: resedit demo

Install
Usage
Supported formats
Parsing signed executables
Signing executables with resedit-js
Notes
Examples
License

Install

npm install resedit

Usage

For detailed code using ResEdit namespace, see Examples.
For more APIs, please see dist directory of the package. And, some test codes may help you for usages.

For ESM (ES Modules):

//import * as PELibrary from 'pe-library';
import * as ResEdit from 'resedit';

For CJS (CommonJS modules including classic Node.js scripts):

//const PELibrary = require('pe-library');
const ResEdit = require('resedit');

If your Node.js version is prior to v20.19.5, require cannot be used for 'resedit' package and you must use 'resedit/cjs' package as described in Migrate from v1.x to v2.x (collapsed in Migration from prior resedit versions area).

<summary>Migration from prior resedit versions</summary>

Migrate from v2.x to v3.x

This major version up includes 'Change requirements of Node.js version (v20.19.5 or later is required)' and 'Remove TypeScript enum usage' only. If your code base (project) meets following conditions, you can safely upgrade to v3.x (without no more actions):

You uses resedit v2.x
- If you use v1.x, please follow Migrate from v1.x to v2.x.
The code base already uses Node.js v20.19.5 or later (including v22, v24, or higher)
- Node.js v18 or earlier is already end-of-life. Upgrade to v22 or v24 is recommended.
- For using Node.js v20, upgrading to v20.19.5 or later would not be difficult.
Following enum's members are not used or used only as values: VersionFileFlags, VersionFileOS, VersionFileDriverSubtype, VersionFileFontSubtype, and VersionFileType
- If you use the members as types (e.g. let x: VersionFileFlags.Debug), rewrite with using typeof (e.g, let x: typeof VersionFileFlags.Debug).

Migrate from v1.x to v2.x

If you use from ES module (.mjs) and load by using import, no need for migration.
If you use from ES module (.mjs) and load by using require (Node.js: via createRequire), replace with import statement: import * as ResEdit from 'resedit'.
If you use from CommonJS module (.cjs) and load by using require, choose followings:
- If you are using under Node.js environment, only update Node.js to v20.19.0 or later
  - Starting from Node.js v20.19.0, you can require synchronous ES module. resedit does not use top-level await, so you can write require('resedit') from CommonJS module.
- Convert CommonJS module to ES module and replace require call with import statement
- Use resedit/cjs module and call load function (see below)
If you use TypeScript,
- For "module": "ES2015" or higher, no need for migration.
- For "module": "CommonJS", import resedit/cjs and call load function

The sample of using resedit/cjs in CommonJS module is:

const { load } = require('resedit/cjs');
load().then((ResEdit) => {
  // ResEdit will be the namespace object of resedit library
  // (for example ResEdit.Data.IconFile is available)
});

Similarly, the sample of using resedit/cjs in TypeScript CommonJS module is:

// You can use `ResEdit` for type references (cannot be used for value references)
import { type ResEdit, load } from 'resedit/cjs';
load().then((RE: typeof ResEdit) => {
  // RE will be the namespace object of resedit library
  // (for example RE.Data.IconFile is available)
});

Supported formats

Windows Executables (PE Format, such as .exe and .dll), both 32-bit and 64-bit, are supported.
- Executables for 16-bit Windows is not supported.
.res file is not supported now.
PNG-based icon data is supported on require('resedit').Resource.IconGroupEntry class.

Parsing signed executables

Parsing signed executables (by using Authenticode or etc.) is not allowed by default and an exception will be thrown if NtExecutable.from receives a signed binary.
To parse signed, { ignoreCert: true } object must be passed to the second argument of NtExecutable.from.
Although the base executable data is signed, NtExecutable.generate will generate unsigned executable binary. If you want to re-sign it, you must use generate-function with signing (see below) or any other signing tool such as Microsoft signtool.

Signing executables with resedit-js

resedit-js provides basic signing process generateExecutableWithSign function, which is based on Authenticode specification and related RFCs.

To keep resedit-js generic library, the followings are required to use signing process.

Encryption / calculating hash (digest) process (e.g. Node.js built-in crypto module)
- A private key data is implicitly required to encrypt data.
DER-format certificate binary (such as *.cer file data or *.p7b file data with DER-format), which is paired with the private key used by encryption process.
(optional) Generating timestamp data, especially communicating with TSA server (e.g. HTTP/HTTPS API)

These requirements are represented as SignerObject. The caller of generateExecutableWithSign function must implement this object to sign executables.

An example code is here: signTest.mjs

Note that resedit-js only provides basic signing process, and provides as beta version. For example adding more attributes/informations to certificates are not supported now.

Some digest algorithms, such as SHA3 algorithms, might not be supported by current Windows.

Notes

It is not strongly recommended that the destination executable file is equal to the source executable file (which is not an intermediate data).

Examples

import * as PELibrary from 'pe-library';
import * as ResEdit from 'resedit';
import * as fs from 'fs';

// load and parse data
const data = fs.readFileSync('MyApp.exe');
// (the Node.js Buffer instance can be specified directly to NtExecutable.from)
const exe = PELibrary.NtExecutable.from(data);
const res = PELibrary.NtExecutableResource.from(exe);

// rewrite resources
// - You can use helper classes as followings:
//   - ResEdit.Resource.IconGroupEntry: access icon resource data
//   - ResEdit.Resource.StringTable: access string resource data
//   - ResEdit.Resource.VersionInfo: access version info data

// -- replace icons

// load icon data from file
// (you can use ResEdit.Data.IconFile to parse icon data)
const iconFile = ResEdit.Data.IconFile.from(fs.readFileSync('MyIcon.ico'));

ResEdit.Resource.IconGroupEntry.replaceIconsForResource(
  // destEntries
  res.entries,
  // iconGroupID
  // - This ID is originally defined in base executable file
  //   (the ID list can be retrieved by `ResEdit.Resource.IconGroupEntry.fromEntries(res.entries).map((entry) => entry.id)`)
  101,
  // lang ('lang: 1033' means 'en-US')
  1033,
  // icons (map IconFileItem to IconItem/RawIconItem)
  iconFile.icons.map((item) => item.data)
);

// -- replace version

const viList = ResEdit.Resource.VersionInfo.fromEntries(res.entries);
const vi = viList[0];
// setFileVersion will set `vi.fixedInfo.fileVersionMS`/`fileVersionLS` and 'FileVersion' string value
// ('1033' means 'en-US')
vi.setFileVersion(1, 0, 0, 0, 1033);
// ('lang: 1033' means 'en-US', 'codepage: 1200' is the default codepage)
vi.setStringValues(
  { lang: 1033, codepage: 1200 },
  {
    FileDescription: 'My application',
    ProductName: 'My product',
  }
);
vi.outputToResourceEntries(res.entries);

// write to another binary
res.outputResource(exe);
const newBinary = exe.generate();
fs.writeFileSync('MyApp_modified.exe', Buffer.from(newBinary));