electrum/contrib/osx

Building macOS binaries

✓ This binary should be reproducible, meaning you should be able to generate binaries that match the official releases.

This guide explains how to build Electrum binaries for macOS systems.

Building the binary

This needs to be done on a system running macOS or OS X.

Notes about compatibility with different macOS versions:

• In general the binary is not guaranteed to run on an older version of macOS than what the build machine has. This is due to bundling the compiled Python into the PyInstaller binary.
• The bundled version of Qt also imposes a minimum supported macOS version.
• If you want to build binaries that conform to the macOS "Gatekeeper", so as to minimise the warnings users get, the binaries need to be codesigned with a certificate issued by Apple, and starting with macOS 10.15 the binaries also need to be notarized by Apple's central server. The catch is that to be able to build binaries that Apple will notarise (due to the requirements on the binaries themselves, e.g. hardened runtime) the build machine needs at least macOS 10.14. See #6128.

We currently build the release binaries on macOS 10.14.6, and these seem to run on 10.13 or newer.

Before starting, you should install brew.

Notes about reproducibility

• We recommend creating a VM with a macOS guest, e.g. using VirtualBox, and building there.
• The guest should run macOS 10.14.6 (that specific version).
• The unix username should be vagrant, and electrum should be cloned directly to the user's home dir: /Users/vagrant/electrum.
• Builders need to use the same version of Xcode; and note that full Xcode and Xcode commandline tools differ! You should build with Xcode 11.3.1 (full Xcode). The path for Xcode should be exactly as follows:

  $ xcode-select -p
  /Users/vagrant/Downloads/Xcode.app/Contents/Developer
  $ xcrun --show-sdk-path
  /Users/vagrant/Downloads/Xcode.app/Contents/Developer/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk
  

  Note: make sure neither command above refers to the Xcode command line tools! If so, rename the cli tools, e.g.

  $ mv /Library/Developer/CommandLineTools /Library/Developer/CommandLineTools2
  

  As a sanity check, make sure $ gcc --version consistently refers to the full Xcode.

• Make sure that you are building from a fresh clone of electrum (or run e.g. git clean -ffxd to rm all local changes).

1. Get Xcode

Notarizing the application requires full Xcode (not just command line tools as that is missing altool).

Get it from here. Unfortunately, you need an "Apple ID" account.

(note: the last Xcode that runs on macOS 10.14.6 is Xcode 11.3.1)

After downloading, uncompress it.

Make sure it is the "selected" xcode (e.g.):

sudo xcode-select -s $HOME/Downloads/Xcode.app/Contents/Developer/

2. Build Electrum

cd electrum
./contrib/osx/make_osx

This creates both a folder named Electrum.app and the .dmg file.

If you want the binaries codesigned for MacOS and notarised by Apple's central server, provide these env vars to the make_osx script:

CODESIGN_CERT="Developer ID Application: Electrum Technologies GmbH (L6P37P7P56)" \
APPLE_ID_USER="me@email.com" \
APPLE_ID_PASSWORD="1234" \
./contrib/osx/make_osx

Verifying reproducibility and comparing against official binary

Every user can verify that the official binary was created from the source code in this repository.

1. Build your own binary as described above.
2. Use the provided compare_dmg script to compare the binary you built with the official release binary.

   $ ./contrib/osx/compare_dmg dist/electrum-*.dmg electrum_dmg_official_release.dmg
   

   The compare_dmg script is mostly only needed as the official release binary is codesigned and notarized. Otherwise, the built .app bundles should be byte-identical. (Note that we are using hdutil to create the .dmg, and its output is not deterministic, but we cannot compare the .dmg files directly anyway as they contain codesigned files)