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 ¶
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 <email@example.com> Date: Thu Jan 2 14:33:58 2020 +0100 - synced to upstrem 1.5.41 commit 287994f4bcfb08f6ca975ccfb1d12f13c664be3c Author: lele <firstname.lastname@example.org> Date: Fri Jan 5 16:29:58 2018 +0100 - v1.1.0 commit 4dff0ed0b3f75579c7b98f983d87601225324c54 (tag: v1.3.9) Author: lele <email@example.com> Date: Fri Jan 5 15:35:25 2018 +0100 - v1.3.9 commit 653ba15a279b9df2e35c7ce85758b11bc04d0afc Author: Lele <firstname.lastname@example.org> Date: Thu Jul 27 16:42:11 2017 +0200 Provided links to the melis website commit 11b778e6f8f45d1e4c23c580b8cdc3f7e5ca025f (tag: 0.20.30) Author: lele <email@example.com> 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 ... + firstname.lastname@example.org + email@example.com + firstname.lastname@example.org + email@example.com 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.
We could not verify that the provided code matches the binary!
As part of our Methodology, we ask:Is the published binary matching the published source code? If not, we tag it
Published code doesn’t help much if it is not what the published app was built from. That is why we try to reproduce the binary. We
- obtain the binary from the provider
- compile the published source code using the published build instructions into a binary
- compare the two binaries
- we might spend some time working around issues that are easy to work around
If this fails, we might search if other revisions match or if we can deduct the source of the mismatch but generally consider it on the provider to provide the correct source code and build instructions to reproduce the build, so we usually open a ticket in their code repository.
In any case, the result is a discrepancy between the app we can create and the app we can find on the app store 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.
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