Eclair Mobile

4 minute read

Published:

Wallet Logo

This app was first launched on 12th April 2018 and currently has more than 10000 downloads, a 4.1 stars rating from 330 users and the latest APK (version 0.4.10) was from 14th February 2020.

Our analysis was done on 22nd December 2019 based on data found in their Playstore description and their website and their source repository. We discuss the issue with verification with the provider here.

We found these ways of contacting the developers:

Help spread awareness for build verifiability

Please help us spread the word, asking Eclair Mobile to support verifiable builds via their Twitter!

Disclaimer

The following Analysis is not a full code review! We plan to make code reviews available in the future but even then it will never be a stamp of approval but rather a list of incidents and bad coding practice. We cannot find and tell you all the dark secrets the wallet providers might have.

Do your own research!

Try out searching for "lost bitcoins", "stole my money" or "scammers" together with the wallet's name, even if you think the wallet is generally trustworthy. For all the bigger wallets you will find accusations. Make sure you understand why they were made and if you are comfortable with the provider's reaction.

The Analysis

This wallet has a really short description. Here it is in full:

Eclair Mobile is a next generation, Lightning-ready Bitcoin wallet. It can be used as a regular Bitcoin wallet, and can also connect to the Lightning Network for cheap and instant payments.

This software is based on eclair, and follows the Lightning Network standard.

No word on custodial or not.

Their website is more informative if only for the link to their GitHub.

eclair-mobile sounds promising.

There, in the description again we find no hints at it being non-custodial.

But in the repository’s wiki finally we find:

Is Eclair Mobile a “real” Lightning Node ?

Yes it is. Eclair Mobile is a real, self-contained lightning node that runs on your phone. It does not require you to run another Lightning Node node at home or in the cloud. It is not a custodial wallet either, you are in full control of your funds.

So … can we reproduce the build?

The build instructions are not very plentiful on the repo’s description:

Developers

  1. clone this project
  2. clone eclair and checkout the android branch.

    Follow the steps here to build the eclair-core library.

  3. Open the Eclair Mobile project with Android studio. You should now be able to install it on your phone/on an emulator.

This has two immediate issues:

  • How do we know which version of “eclair” should we use? This should be resolved with a git submodule.
  • Compiling with Android Studio is not easy to automate and should not be necessary.
  • Branches are not a good way of referencing revisions of a repository. The “android branch” has 1938 revisions and if I want to check anything but the latest revision I have little to go by to find which app would match to which state of the branch.

but let’s see how compiling looks once these issues are resolved as we have little hope to verify the current apk …

$ git clone git@github.com:ACINQ/eclair-mobile.git
$ git clone git@github.com:ACINQ/eclair.git
$ cd eclair
$ git checkout android
$ docker run -it -v $PWD/eclair:/eclair -v $PWD/eclair-mobile:/eclair-mobile --workdir / electrum-android-builder-img
user@d0cf683a144a:/$ sudo su -
root@d0cf683a144a:~# apt update      
root@d0cf683a144a:~# apt install maven
root@d0cf683a144a:~# mvn install -DskipTests
...
[INFO] --- maven-compiler-plugin:3.1:testCompile (default-testCompile) @ eclair-core_2.11 ---
[INFO] Nothing to compile - all classes are up to date
[INFO]
[INFO] --- scala-maven-plugin:3.4.2:testCompile (scalac) @ eclair-core_2.11 ---
[INFO] /eclair/eclair-core/src/test/java:-1: info: compiling
[INFO] /eclair/eclair-core/src/test/scala:-1: info: compiling
[INFO] Compiling 114 source files to /eclair/eclair-core/target/test-classes at 1577007350665
[ERROR] /eclair/eclair-core/src/test/scala/fr/acinq/eclair/blockchain/bitcoind/BitcoindService.scala:74: error: value writeString is not a member of object java.nio.file.Files
[ERROR]       Files.writeString(new File(PATH_BITCOIND_DATADIR.toString, "bitcoin.conf").toPath, conf)
[ERROR]             ^
[ERROR] one error found
[INFO] ------------------------------------------------------------------------
[INFO] Reactor Summary for eclair_2.11 0.3.4-android-SNAPSHOT:
[INFO]
[INFO] eclair_2.11 ........................................ SUCCESS [  1.951 s]
[INFO] eclair-core_2.11 ................................... FAILURE [ 28.245 s]
[INFO] eclair-node ........................................ SKIPPED
[INFO] ------------------------------------------------------------------------
[INFO] BUILD FAILURE

So following the instructions we didn’t get far and for now hope for better documentation and remain with the verdict: This app is not verifiable.

Verdict Explained

Not verifiable: The provided Open Source Code could not be verified to match the app released on Google Play

This verdict means that the provider did share some source code but that we could not verify that this source code matches the released app. This might be due to the source being released later than the app or due to the provided instructions on how to compile the app not being sufficient or due to the provider excluding parts from the public source code. In any case, the result is a discrepancy between the app we can create and the app we can find on GooglePlay and any discrepancy might leak your backup to the server on purpose or by accident.

As we cannot verify that the source provided is the source the app was compiled from, this category is only slightly better than closed source but for now we have hope projects come around and fix verifiability issues.

The app cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The app might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.