Help spread awareness for build reproducibility
Please help us spread the word, asking Bitcoin Wallet Hexa to support reproducible builds via their Twitter!
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 ¶
The page footer on their website answers most of our questions:
Bitcoin Only Wallet | Best Android Bitcoin Wallet | IOS Bitcoin Wallet | Non Custodial Bitcoin Wallet | Simple Bitcoin Wallet | Multisig wallet | Stack Sats | Donate Bitcoin | Bitcoin Donation | Buy bitcoin in UK | Crypto wallet | Send bitcoin | Beginners bitcoin wallet | Shamir Secret Sharing Bitcoin Wallet
So it’s “Non Custodial Bitcoin Wallet”. There is also a link to their Github and while not equipped with a FOSS license, it is public source code of a wallet.
So the build instructions looked lacking from the start as there is no word about building the apk but only about running the app, we tried it nevertheless:
$ git clone https://github.com/bithyve/hexa $ cd hexa/ $ git checkout v1.4.1 $ docker run --rm -v$PWD:/mnt --workdir=/mnt -it walletscrutiny/android bash root@af2c99dc5b57:/mnt# apt update root@af2c99dc5b57:/mnt# apt install curl npm rubygems -y root@af2c99dc5b57:/mnt# curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | apt-key add - root@af2c99dc5b57:/mnt# echo "deb https://dl.yarnpkg.com/debian/ stable main" | tee /etc/apt/sources.list.d/yarn.list root@af2c99dc5b57:/mnt# apt update root@af2c99dc5b57:/mnt# apt install yarn -y root@af2c99dc5b57:/mnt# npm install npm@latest -g root@af2c99dc5b57:/mnt# npm install -g rn-nodeify root@af2c99dc5b57:/mnt# gem install cocoapods ... Building native extensions. This could take a while... ERROR: Error installing cocoapods: ERROR: Failed to build gem native extension. ... root@7a3a4f43290e:/mnt# yarn install ... patch cocoapods ./setup.sh: 14: pod: not found Done in 132.25s.
and as the above is only the good guesses out of 35 commands typed so far, this is where we give up and consider the app not verifiable due to lacking build instructions.
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 binary 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 binary we can create and the binary we can find for download 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 binary 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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