Help spread awareness for build reproducibility
Please help us spread the word, asking COINiD Vault 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 ¶
This app is the companion app for the Bitcoin Wallet for COINiD and allows a setup with this being the actual wallet that holds the private keys without ever being online and the other app being the wallet interface that knows balance and receiving addresses but that can’t send coins without this app.
This app recently reached 1000 downloads, which is the minimum for being analyzed.
Unfortunately the GitHub repository has not much in terms of build instructions. In fact, this is their complete Readme.md:
Proper readme coming soon. If you have any questions you can contact us on our Telegram or via email.
We are currently not including the secrets.js in the repo. If you want to compile the vault to test it you need to add the following to src/config/secrets.js.
export const p2pCommonSecret = ''; export const encryptPrivateSalt = ''; export const pinSecret = '';
So the app is not only lacking build instructions but also parts of the source code (secrets.js). As such a
secrets.js can’t be kept very secret when delivering the app to users, not including it in the repository does not achieve much.
The FAQ is clear about this app being a wallet by our understanding:
Do my private key ever leave my device? No, your private key never leaves your device. You are in full control of your private key.
Unfortunately it is also clear about not being reproducible:
Do you provide deterministic builds? Since we need to distribute the app via the App Store that is not possible. The source is however available on our Github so that anyone can review and compile it.
This is the first time we hear this claim. Why would the Android app have to be non-deterministic because of Apple?
For now we consider this app not verifiable and hope to see the issues resolved soon.
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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