This app was first launched on 30th January 2017 and currently has more than 1000 downloads, a 4.1 stars rating from 17 users and the latest APK (version 1.5.40) was from 3rd June 2019.
Our analysis was done on 7th April 2020 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:
- Website: www.melis.io
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.
Update: The provider replied to our issue so we took another look.
On Google Play we find no claims of this wallet being non-custodial or open source.
On their website they claim
With Melis you have the complete control of your bitcoins and private keys
which probably means non-custodial. And
Melis is open source, published on GitHub.
So this is a Cordova app. The build instructions are there … promising so far. Time to get more hands-on …
$ git clone https://github.com/melis-wallet/melis-cm-client $ cd melis-cm-client/ $ git log commit 61246945952eb3c50ef8c7800eba84bea1142836 (HEAD -> release, origin/release, origin/HEAD) Author: lele <firstname.lastname@example.org> Date: Thu Jan 2 14:33:58 2020 +0100 - synced to upstrem 1.5.41 commit 287994f4bcfb08f6ca975ccfb1d12f13c664be3c Author: lele <email@example.com> Date: Fri Jan 5 16:29:58 2018 +0100 - v1.1.0 commit 4dff0ed0b3f75579c7b98f983d87601225324c54 (tag: v1.3.9) Author: lele <firstname.lastname@example.org> Date: Fri Jan 5 15:35:25 2018 +0100 - v1.3.9 commit 653ba15a279b9df2e35c7ce85758b11bc04d0afc Author: Lele <email@example.com> Date: Thu Jul 27 16:42:11 2017 +0200 Provided links to the melis website commit 11b778e6f8f45d1e4c23c580b8cdc3f7e5ca025f (tag: 0.20.30) Author: lele <firstname.lastname@example.org> Date: Thu May 11 09:34:24 2017 +0200 - public release $ rgrep "1\.5\.40" . $ rgrep "1\.5\.41" . ./package.json: "version": "1.5.41",
So this repository has a total of 5 commits with the latest being ahead of what we would like to reproduce (1.5.40) and the prior one being much behind (1.1.0).
Lets see if the build instructions are helpful:
$ docker run --rm -v $PWD:/mnt --workdir /mnt -it beevelop/cordova bash root@696ffb01eee2:/mnt# apt update root@696ffb01eee2:/mnt# apt install -y phantomjs phantomjs is already the newest version (2.1.1+dfsg-1). root@696ffb01eee2:/mnt# npm install -g npm bower ember-cli yarn ... + email@example.com + firstname.lastname@example.org + email@example.com + firstname.lastname@example.org root@696ffb01eee2:/mnt# git --version git version 2.7.4 root@696ffb01eee2:/mnt# node --version v10.16.3 root@696ffb01eee2:/mnt# wget https://github.com/melis-wallet/melis-cm-client/releases/download/1.5.1/ember-leaf-theme-basic-master-9601b6f57e468dd0ccc4bbcdb01ae1aebfb0153c.zip root@696ffb01eee2:/mnt# unzip ember-leaf-theme-basic-master-9601b6f57e468dd0ccc4bbcdb01ae1aebfb0153c.zip root@8797b57b1bb3:/mnt# mv ember-leaf-theme-basic-master-9601b6f57e468dd0ccc4bbcdb01ae1aebfb0153c ../ember-leaf-theme-basic root@696ffb01eee2:/mnt# yarn root@696ffb01eee2:/mnt# bower install --allow-root root@696ffb01eee2:/mnt# node i18n/generate-melis-i18n.js root@696ffb01eee2:/mnt# build/cordova-setup.sh Usage: config <platform> <target> root@696ffb01eee2:/mnt# build/build-android.sh Usage: build <target> <version> <keystorepassword>
So with the provider’s help we get a bit further but we still did not manage to
get to a compiled app. For build reproduction we would need an unsigned apk. The
keystorepassword therefore should not be needed.
Also the zip file being downloaded from the provider’s GitHub is certainly kind of closed source as is and would require investigation apart from how it is cumbersome to use. It would probably be more convenient to provide that folder as a git submodule.
We are looking forward to finally reproducing a build but for now remain with the verdict: not verifiable.
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.