@electron/osx-sign

Codesign Electron macOS apps

About

@electron/osx-sign minimizes the extra work needed to eventually prepare your apps for shipping, providing options that work out of the box for most applications. Additional configuration is available via its API.

There are two main functionalities exposed via this package:

• Signing macOS apps via sign functions. Under the hood, this uses the codesign utility.
• Creating .pkg installer packages via flat functions. Under the hood, this uses the productbuild utility.

Installation

@electron/osx-sign is integrated into other Electron packaging tools, and can be configured accordingly:

• Electron Packager
• Electron Forge

You can also install @electron/osx-sign separately if your packaging pipeline does not involve those tools:

npm install --save-dev @electron/osx-sign

Code signing

The signing procedure implemented in this package is based on what described in Electron's Code Signing Guide.

Prerequisites

• You must be a registered member of the Apple Developer Program. Please note that you could be charged by Apple in order to get issued with the required certificates.
• You must have Xcode installed from the Mac App Store. It is not recommended to download your copy from other 3rd party sources for security reasons.
• You must have Xcode Command Line Tools installed. To check whether it is available, try xcode-select --install and follow the instructions.
• To distribute your app on the Mac App Store, You must create a Mac App on App Store Connect.
• You must give your app a unique Bundle ID.
• You must give your app a version number.

Certificates

In order to distribute your application either inside or outside the Mac App Store, you will have to have the following certificates from Apple after becoming a registered developer.

Certificates can be created through the Certificates, Identities & Profiles page in the Apple Developer website or via Account Preferences in Xcode.

For distribution inside the Mac App Store, you will need to create:

• Mac App Distribution: 3rd Party Mac Developer Application: * (*)
• Mac Installer Distribution: 3rd Party Mac Developer Installer: * (*)

For distribution outside the Mac App Store:

• Developer ID Application: Developer ID Application: * (*)
• Developer ID Installer: Developer ID Installer: * (*)

After you create the necessary certifications, download them and open each so that they are installed in your keychain. We recommend installing them in your system default keychain so that @electron/osx-sign can detect them automatically.

[!TIP] Apple developer certificates tend to come in related pairs. It’s simplest to install both of them for future use. However, if you only want to distribute outside the Mac App Store, there is no need to have the 3rd Party Mac Developer ones installed, and vice versa.

API

import { sign } = from '@electron/osx-sign'
const opts = {
  app: 'path/to/my.app'
};
sign(opts)
  .then(function () {
    // Application signed
  })
  .catch(function (err) {
    // Handle the error
  })

The only mandatory option for sign is a path to your .app package. Configuration for most Electron apps should work out of the box. For full configuration options, see the API documentation.

Usage examples

Signing for Mac App Store distribution

import { sign } from '@electron/osx-sign'
const opts = {
  app: 'path/to/my.app',
  // optional parameters for additional customization
  platform: "mas", // should be auto-detected if your app was packaged for MAS via Packager or Forge
  type: "distribution", // defaults to "distribution" for submission to App Store Connect
  provisioningProfile: 'path/to/my.provisionprofile', // defaults to the current working directory
  keychain: 'my-keychain', // defaults to the system default login keychain
};
sign(opts)
  .then(function () {
    // Application signed
  })
  .catch(function (err) {
    // Handle the error
  })

Mac App Store apps require a Provisioning Profile for submission to App Store Connect. We recommend having the provisioning profile for distribution placed in the current working directory and the signing identity installed in the default keychain.

The app is not expected to run after codesigning since there is no provisioned device, and it is intended only for submission to App Store Connect. Since @electron/osx-sign adds the entry com.apple.developer.team-identifier to a temporary copy of the specified entitlements file (with the default option preAutoEntitlements), distribution builds can no longer be run directly.

To run an app codesigned for distribution locally after codesigning, you may manually add ElectronTeamID in your Info.plist and com.apple.security.application-groups in the entitlements file, and set preAutoEntitlements: false for @electron/osx-sign to avoid this extra bit. Note that "certain features are only allowed across apps whose team-identifier value match" (Technical Note TN2415).

Alternatively, set the app's type to development to codesign a development version of your app, which will allow it to be run on your development provisioned machine. Apps signed for development will not be eligible for submission via App Store Connect.

Signing with --deep

Some subresources that you may include in your Electron app may need to be signed with --deep. This is not typically safe to apply to the entire Electron app and therefore should be applied to just your file.

sign({
  app: 'path/to/my.app',
  optionsForFile: (filePath, { platform }) => {
    // The second argument provides additional context about the current signing
    // operation, such as the resolved `platform` ('darwin' or 'mas').

    // For our one specific file we can pass extra options to be merged
    // with the default options
    if (path.basename(filePath) === 'myStrangeFile.jar') {
      return {
        additionalArguments: ['--deep'],
      };
    }

    // Just use the default options for everything else
    return null;
  },
});

Signing legacy versions of Electron

@electron/osx-sign maintains backwards compatibility with older versions of Electron, but generally assumes that you are on the latest stable version.

If you are running an older unsupported version of Electron, you should pass in the version option as such:

sign({
  app: 'path/to/my.app',
  version: '0.34.0',
});

Flat installer packaging

This module also handles the creation of flat installer packages (.pkg installers).

[!NOTE] Modern .pkg installers are also named "flat" packages for historical purposes. Prior to Mac OS X Leopard (10.5), installation packages were organized in hierarchical directories. OS X Leopard introduced a new flat package format that is used for modern .pkg installers.

API usage

import { flat } = '@electron/osx-sign'
flat({
  app: 'path/to/my.app'
})
  .then(function () {
    // Application flattened
  })
  .catch(function (err) {
    // Handle the error
  })

The only mandatory option for flat is a path to your .app package. For full configuration options, see the API documentation.

Pure-JavaScript packaging

By default flat shells out to Apple's pkgbuild/productbuild binaries. Passing implementation: 'js' switches to a bundled pure-JavaScript implementation of the flat package format that is typically 4–5× faster on a real Electron app and works on any platform (Linux/Windows included) for unsigned packages:

await flat({
  app: 'path/to/my.app',
  implementation: 'js',
});

The JS implementation reimplements the entire flat package stack — the cpio payload archive, Apple's Bill-of-Materials (Bom) binary format, the PackageInfo/Distribution documents and the outer xar archive. Its output is verified against the native tools by an extensive parity test suite (spec/pkg-utils/): uncompressed payloads are byte-identical, lsbom output matches on every field, and the XML documents are byte-identical modulo the generator-version attribute. Run yarn bench to reproduce the performance comparison on your machine.

Notes on intentional differences from the native tools:

• The payload is gzip-compressed as a standards-compliant multi-member stream so members can be compressed in parallel. Compressed output is ~3% larger than Apple's private zlib flavor; decompressed content is identical.
• Extended attributes are not preserved (no AppleDouble ._* entries are generated).
• The app's Info.plist must be XML; binary property lists are rejected with an error.
• Hardlinked files are stored as independent copies rather than deduplicated the way pkgbuild archives them (Electron apps use symlinks, not hardlinks).
• Individual files larger than 4 GB are rejected (the flat package Bom format stores 32-bit sizes; Size64 support is not implemented).
• Files with NFC-normalized (composed) Unicode names are packaged correctly; native pkgbuild silently omits such files from the payload.
• When a signing identity is provided, the built package is signed with productsign, which requires macOS.

CLI

@electron/osx-sign also exposes a legacy command-line interface (CLI) for both signing and installer generation. However, we recommend using the JavaScript API as it has a more complete API surface (e.g. optionsForFile is only available via JS).

# install the package locally into devDependencies
npm install --save-dev @electron/osx-sign

# Sign a packaged .app bundle
npx electron-osx-sign path/to/my.app [options ...]

# Create a .pkg installer from a packaged .app bundle
npx electron-osx-flat path/to/my.app [options ...]

For full options, use the --help flag for either command.

Debug

The debug module is used to display advanced logs and messages. If you are having problems with signing your app with @electron/osx-sign, run your signing scripts with the DEBUG=electron-osx-sign* environment variable.

Test

The project's configured to run automated tests on GitHub Actions.

If you wish to manually test the module, you need to first generate a self-signed certificate via the spec/ci/generate-identity.sh script.