Breez: Lightning Network Client & Point-of-Sale

Published:

Wallet Logo

This Android app currently has more than 1000 downloads and the latest release is version Varies with device.

Our last analysis was done on 28th December 2019 based on data found in their Google Play description and their website and their source repository. We discuss issues with the provider here.

We found these ways of contacting the developers:

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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 questionable coding practice. Nasa sends probes to space that crash due to software bugs despite a huge budget and stringent scrutiny.

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

A description to our liking. Here it is in full:

Breez is a Lightning Network client which makes paying in bitcoin a seamless experience. With Breez, anyone can send or receive small payments in bitcoin. It’s simple, fast and safe.

Ok, seamless, lightning, … nice.

Breez is a non-custodial service that uses lnd and Neutrino under the hood.

We want to hear that! Be your own bank!

For more technical information, please go to: https://github.com/breez/breezmobile.

So they are non-custodial and provide source code. More work for us :)

Warning: the app is still in beta and there is a chance your money will be lost. Use this app only if you are willing to take this risk.

That’s certainly inspiring more confidence than other apps with 2 months of track record claiming to be the best in the world. :)

Well, in terms of Build Instructions the app is lacking.

$ git clone git@github.com:breez/breezmobile.git
$ cd breezmobile/
$ git tag
0.5-openbeta
0.5.8-openbeta
0.5.9-openbeta
0.7-openbeta
0.8.improvements

As on the playstore it says “Current Version: Varies with device”, we go with what google gives us when we install it on a phone: 0.8-beta. The best match above would thus be the tag 0.8.improvements:

$ git checkout 0.8.improvements 
$ cat android/app/build.gradle | grep version
        versionCode 1
        versionName "0.8-beta"
            versionNameSuffix "-pos"

looks good so far. For now. We will not guess like this in the future.

Build breez.aar and bindings.framework as decribed in breez/breez

$ git submodule status 
$

… so … the build instructions give no clue which version of breez/breez to build and there is no submodule?

$ git clone git@github.com:breez/breez.git
$ cd breez
$ git tag
0.5-openbeta
0.5.8-openbeta

Had there been a 0.8… in the breez project, we would have had a clue where to go next but absent that, there is no hope of reproducing the app. For now our verdict is: not verifiable.

Verdict Explained

Not verifiable: The provided 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.