BLW: Bitcoin and Lightning Wallet

Published:

Wallet Logo

This Android app was first launched on 1st May 2018 and currently has more than 10000 downloads, a 4.1 stars rating from 310 users and the latest release is version 0.4.5.

Our last analysis was done on 11th May 2020 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:

Older reviews

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

So the provider contacted us and cleared many issues we had in our first review. Let’s see how far we get this time …

First thing we notice is that there are still no build instructions on the GitHub page but according to above issue it’s simple enough:

The version we got from Google Play is this:

$ sha256sum BLW.apk 
ffcffa9d3053590b98f845622ab5a4748023245fbacc48f6798ca9ff753f86c6  BLW.apk
$ apktool d -o BLW BLW.apk 
$ cat BLW/apktool.yml | grep "versionCode\|versionName"
  versionCode: '150'
  versionName: 0.4.4

So …

$ git clone https://github.com/btcontract/lnwallet.git
$ cd lnwallet
$ git tag
0.4-146
0.4.1
0.4.1-147
0.4.2
0.4.3
0.4.4
$ git checkout 0.4.4 
$ docker run -it --volume $PWD:/mnt --workdir /mnt --rm mycelium-wallet bash 
# wget https://downloads.gradle-dn.com/distributions/gradle-3.3-bin.zip
# unzip gradle-3.3-bin.zip
# /opt/android-sdk/tools/bin/sdkmanager ndk-bundle
# ./gradle-3.3/bin/gradle assembleDebug
Parallel execution is an incubating feature.
Checking the license for package CMake 3.6.4111459 in /opt/android-sdk/licenses
License for package CMake 3.6.4111459 accepted.
Preparing "Install CMake 3.6.4111459 (revision: 3.6.4111459)".
"Install CMake 3.6.4111459 (revision: 3.6.4111459)" ready.
Finishing "Install CMake 3.6.4111459 (revision: 3.6.4111459)"
Installing CMake 3.6.4111459 in /opt/android-sdk/cmake/3.6.4111459
"Install CMake 3.6.4111459 (revision: 3.6.4111459)" complete.
"Install CMake 3.6.4111459 (revision: 3.6.4111459)" finished.
Incremental java compilation is an incubating feature.

FAILURE: Build failed with an exception.

* What went wrong:
A problem occurred configuring project ':app'.
> No toolchains found in the NDK toolchains folder for ABI with prefix: mips64el-linux-android

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Which is again the known issue from last time: The gradle version is outdated. It should be 3.1 or above but is defined as

# cat build.gradle | grep "tools\.build"
        classpath 'com.android.tools.build:gradle:2.3.0'

So if there is a good reason for using an old gradle version (2.3 is from early 2015), the team should explain that.

Sadly we again fail to compile due to lack of sufficiently clear build instructions and come to the verdict 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.