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BTC.com - Bitcoin Wallet

latest release: 4.4.7 last analysed  3rd March 2021 Not reproducible from source provided  
3.4 ★★★★★
8172 ratings
500thousand
9th September 2015

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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.

If you find something we should include, you can create an issue or edit this analysis yourself and create a merge request for your changes.

The Analysis 

This app claims:

  • Bitcoin (BTC) & Bitcoin Cash (BCH) support
  • 100% control of your private keys

so it’s a self-custodial BTC wallet. And it’s also open source:

This wallet is a free and open source software. You can view the code on GitHub at http://github.com/blocktrail/blocktrail-wallet.

That’s great but can we reproduce the app?

On Google Play the “current version” is 4.4.7 and on GitHub we find a tag for that.

The Readme.md also contains compile instructions. Let’s do this:

$ git clone https://github.com/blocktrail/blocktrail-wallet
$ cd blocktrail-wallet/
$ git checkout v4.4.7 
$ docker run -it --volume $PWD:/mnt --workdir /mnt --rm beevelop/cordova bash
root@f74eea3c3d23:/mnt# npm install -g npm # make sure npm is latest version
root@f74eea3c3d23:/mnt# npm_config_engine_strict=false npm install -g ionic@4.3.1 cordova@8.1.2 gulp
root@f74eea3c3d23:/mnt# npm install
(node:39) ExperimentalWarning: The fs.promises API is experimental
npm ERR! code 1
npm ERR! path /mnt/node_modules/@sentry/cli
npm ERR! command failed
npm ERR! command sh -c node scripts/install.js
npm ERR! Error: Command failed: /mnt/node_modules/@sentry/cli/sentry-cli --version
npm ERR! error: Failed to load .sentryclirc file from the home folder.
npm ERR!   caused by: Permission denied (os error 13)

npm ERR! A complete log of this run can be found in:
npm ERR!     /root/.npm/_logs/2021-03-05T02_14_24_795Z-debug.log

so as .sentryclirc apparently is a file that has to be in the home folder with some sort of credentials, we probably can’t build the project without this further step and conclude the app is not verifiable.

Apart from there being source code it is worth mentioning that the app was not updated since July 2019 and many 1* ratings complain about financial loss!

Verdict Explained

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 Unreproducible!  

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

  1. obtain the binary from the provider
  2. compile the published source code using the published build instructions into a binary
  3. compare the two binaries
  4. 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.

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.