Reproducible Builds for iOS and Android

This page contains instructions for verifying that Telegram's open source code is exactly the same as the code that is used to build the apps that are available in the App Store, Google Play and directly on the Telegram website.

Warning: Telegram supports reproducible builds as of version 5.13. Bear in mind that, at this stage, the verification process should be considered experimental. We will be updating our apps and these instructions to make this process as straightforward as possible.

• Telegram for Android
• Telegram for iOS

Please read the relevant notes and troubleshooting section carefully.

---

Reproducible Builds for Android

Step 1. Install Docker

Docker can be obtained here. Once the installation is complete, log into your Docker account > Preferences > Advanced and configure the amount of resources Docker may use:

We recommend using the maximum amount allowed by your system's hardware, in order to speed up the build time.

Step 2. Confirm which version you have installed on your Android device

You can find the version/build number at the bottom of the Settings page. Note that Telegram supports reproducible builds starting with version 5.13.

The commit tag to checkout source code for the example above will be release-5.13.0_1821.

Please make sure that you're using the correct version and build number of the version you want to check (and not the one from this example ).

The part after the version number will help you know in which folder to look for the correct APK when you've finished building the app (Step 4):

• “Direct” after version number means that the APK will be inside the “afat/standalone” folder.
• “Universal” after version number means that the APK will be inside the “afat/release” folder.
• If you have Android Version 6.0 or greater, your APK folder will have the “_SDK23” suffix.
• “arm64-v8a” - folder name will start with “arm64”.
• “armeabi-v7” - folder name will start with “armv7”.
• “x86” - folder name will start with “x86”.
• “x86_64” - folder name will start with “x64”.

Step 3. Obtain the source code

Open Terminal, run the commands:
git clone https://github.com/DrKLO/Telegram.git $HOME/telegram-android
cd $HOME/telegram-android
git checkout release-{VERSION AND BUILD NUMBER FROM STEP 2}

For our example, the command would be:
git checkout release-5.13.0_1821

Step 4. Build the app

Open Terminal, run the commands:
cd $HOME/telegram-android
docker build -t telegram-build .

docker run --rm -v "$PWD":/home/source telegram-build

These commands will produce 9 different APKs for different target SDK versions and CPU ABIs.

These APKs can be found in:
$HOME/telegram-android/TMessagesProj/build/outputs/apk/

Use the folder name from Step 2 to find the correct folder that holds the same APK as installed on your device. For example, for non-universal Android 9.0 arm64-v8a, the path to your APK will be:
$HOME/telegram-android/TMessagesProj/build/outputs/apk/arm64_SDK23/release/app.apk
Copy this APK to the root source directory by running this command in Terminal:
cp $HOME/telegram-android/TMessagesProj/build/outputs/apk/arm64_SDK23/release/app.apk $HOME/telegram-android/telegram_built.apk

Step 5. The Telegram APK installed on your device

You will need adb for this step.

If you downloaded your APK directly from Telegram's website, use the package name org.telegram.messenger.web in this step. To verify the Google Play APK, use org.telegram.messenger.

Connect your device to the computer, open Terminal, run the commands:
adb shell pm path org.telegram.messenger

The output will look something like this:
package:/data/app/org.telegram.messenger-_zOSURFEx2GpHM8UDF_PVg==/base.apk
By using this information, pull the APK from your device to $HOME/telegram-android using command:
adb pull /data/app/org.telegram.messenger-_zOSURFEx2GpHM8UDF_PVg==/base.apk $HOME/telegram-android/telegram_store.apk

Step 6. Compare the APKs

Open Terminal, run the commands:
cd $HOME/telegram-android
python apkdiff.py telegram_store.apk telegram_built.apk
If the APKs are the same, you will see
APKs are the same!

Tada! Otherwise, something went wrong.

If your APKs don't match, please make sure that you chose the correct code version and the right SDK.

Check out the Troubleshooting section first in case you run into trouble.

---

Reproducible Builds for iOS

The verification process for iOS builds is, unfortunately, a lot more complex than for Android. The two main issues with Apple's current policies and infrastructure are as follows:

1. Apple insists on using FairPlay encryption to “protect” even free apps from “app pirates” which makes obtaining the executable code of apps impossible without a jailbroken device. To solve this issue, Apple would simply need to allow submitting unencryptable binaries to the App Store. This would not affect security since the code would still be signed – and would enable anyone to check the integrity of apps supporting reproducible builds without endangering the integrity and security of their devices.

2. Building your own reproducible binaries is difficult because macOS doesn't support containers like Docker. If Apple followed in the footsteps of Linux (and even Microsoft!) and added container support, it would eliminate the need for steps 1-3 in the guide below.

As things stand now, you'll need a jailbroken device, at least 1,5 hours and approximately 90GB of free space to properly set up a virtual machine for the verification process.

To provide a stable and easily reproducible environment, Telegram iOS builds are compiled on a virtual machine. Parallels is used to verify the builds.

Step 1. Install the Parallels virtual machine

Parallels can be obtained here, it features a fully-functional trial version.

Step 2. Install the latest version of macOS Catalina

To download an image that can be installed on the virtual machine, open the App Store, search for “Catalina” and click “View”.

This will open a system pop-up offering to download the OS:

Choose “Download” and wait for the download to finish. > If you were not using the latest version of the OS, your system may start updating instead. Please finish updating to download macOS Catalina. When done, open Parallels and choose macOS Catalina:

Before starting the installation, configure the virtual machine:

Change the name of the virtual machine to macos10_15_Xcode12_2

Hardware > Processors: 2-4
Memory > 4GB may suffice but 8GB is recommended

You will get something like this:

Parallels may request access to your microphone and camera, this is not required – just press Close.

Your Apple ID is also not required, you can choose Set Up Later.

Use “telegram” for both the account name and password.

Do not ever use the password “telegram” for anything else, it's cursed.

Now install Parallels tools from the menu bar:

After the system restarts, log in.
Open Terminal and run:
sudo visudo
Enter the password “telegram”

Find this line at the end of the file:
%admin ALL=(ALL) ALL
Press “i” on your keyboard, add “NOPASSWD:”
%admin ALL=(ALL) NOPASSWD: ALL
Press Escape.
Type in “:wq”
Press Enter

In the terminal, run:
sudo systemsetup -setcomputersleep Never

Step 3. Install SSH keys on the virtual machine

In the virtual machine, open System Settings > Sharing and enable Remote Login.

In the virtual machine, open Terminal and run:
mkdir -p .ssh; nano .ssh/authorized_keys

In your main OS, open Terminal and run:
if [ ! -e ~/.ssh/id_rsa.pub ]; then ssh-keygen -t rsa -b 4096; fi && cat ~/.ssh/id_rsa.pub | pbcopy

If you see the line “Enter file in which to save the key (/Users/…/.ssh/id_rsa):”, press Enter
In the virtual machine, press CMD+V
Then Ctrl+O, Ctrl+X

Step 4. Install Xcode version 12.2

In the virtual machine, open Safari and go to https://developer.apple.com
Sign in to your Account:

Go to Downloads > More
Enter Xcode in the search field and find the version 12.2

Once the installation is complete, open the file Xcode 12.2.xip. The system will unarchive the app into the same folder. Move it to the Applications folder using Finder.

On the virtual machine, run this command from the terminal:
sudo xcode-select -s /Applications/Xcode.app/Contents/Developer

Shut down the virtual machine.

Step 5. Obtaining the source code

git clone --recursive https://github.com/TelegramMessenger/telegram-ios.git $HOME/telegram-ios
cd $HOME/telegram-ios
git checkout release-${VERSION_NUMBER}

E.g., git checkout release-7.3. Please note that you need to check out the whole git history as the build version depends on the number of commits in the repository.

Step 6. Downloading Bazel 3.7.0 to $HOME/bazel/bazel

mkdir -p $HOME/bazel && cd $HOME/bazel
curl -O -L https://github.com/bazelbuild/bazel/releases/download/3.7.0/bazel-3.7.0-darwin-x86_64
mv bazel-3.7.0-darwin-x86_64 bazel

Check that you have downloaded the correct version:
chmod +x bazel
./bazel --version

Step 7. Building the app

Open Terminal, run the commands:
cd $HOME/telegram-ios BAZEL="$HOME/bazel/bazel" sh buildbox/build-telegram.sh verify

If the environment has been set up correctly, this will start the building process. Note that this step can easily take 30-40 minutes. The average build time on a MacBook Pro (i9 6 core) is 35 minutes.

Once the process is complete the resulting IPA file can be found in build/artifacts/Telegram.ipa
All the following steps will be made via Terminal on your main system.

Step 8. Downloading a decrypted version of the app from the App Store

This step requires a jailbroken device equipped with tools for decrypting apps. We‘d love to make this process more simple but that’s what you get for using Apple tech.

Step 9. Comparing the AppStore build and the version built in the virtual machine

Install the necessary tools:
if ! type brew > /dev/null; then /usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"; fi && brew install python3

Run
python3 tools/ipadiff.py build/artifacts/Telegram.ipa PATH-TO-THE-IPA-FILE-FROM-STEP-9

1. cd telegram-ios > Enter
2. python3 tools/ipadiff.py build/artifacts/Telegram.ipa /path/ > Enter

In case of a successful comparison, you will get a text along these lines:

IPAs are equal, except for the files that can't currently be checked:
    Excluded files that couldn't be checked due to being encrypted:
        PlugIns/SiriIntents.appex/SiriIntents
        PlugIns/Widget.appex/Widget
        PlugIns/NotificationContent.appex/NotificationContent
        PlugIns/NotificationService.appex/NotificationService
        PlugIns/Share.appex/Share
    IPAs contain Watch directory with a Watch app which can't be checked currently.
    IPAs contain .car (Asset Catalog) files that are compiled by the App Store and can't currently be checked:

        Frameworks/TelegramUI.framework/Assets.car
        Assets.car
    IPAs contain .nib (compiled Interface Builder) files that are compiled by the App Store and can't currently be checked:
        Base.lproj/LaunchScreen.nib

In case of any mismatches, you'll get a detailed report.

iOS: Notes

1. You will get a warning if the archive created in Step 7 contains encrypted files. If all these files are in the PlugIns subfolder, they represent various system extensions (e.g. external sharing, Siri, 3D touch). Decrypting such files using existing ways of receiving app archives via Jailbreak is non-trivial (but we're working on resolving this issue). If you do manage to decrypt them, e.g. on iOS 8, they will be matched.

2. You will be notified if the archive includes an Apple Watch app. The watch app will soon no longer be included in the archive.

3. Files with the .car extension are app resource archives (images, sounds) which were compiled and processed specifically for the target device. The App Store processes them in non-trivial ways, we're planning on getting rid of them in future versions.

4. The LaunchScreen.nib file is an empty file containing a description of the interface which is displayed by the system before the app is launched. It is processed by the App Store in a non-trivial way but doesn't contain any code and therefore may be ignored.

---

Troubleshooting

If you encounter any issues with obtaining the code, building and comparing the apps, please contact us at @botsupport and include the hashtag #reproducibleBuilds with your message describing the problem.

Troubleshooting: Android

1. Make sure that you checkout the correct version of the code.

2. Make sure that you build the app using the right SDK.

3. If the gradle version used in the Dockerfile is not available anymore and building of the Docker image fails, wait for a Dockerfile update or update manually to lastest available version.

…

We will update this section with information on overcoming other common issues.