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Zap: Bitcoin Lightning Wallet

latest release: Varies with device last analysed  27th April 2021 Reproducible when tested  

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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 questionable coding practice. Nasa sends probes to space that crash due to software bugs despite a huge budget and stringent scrutiny.

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 

Here is the output using our test script on the binary from Google Play:

appId:          zapsolutions.zap
signer:         24a0e944a65d8cea692653e1a132a042c37be334f1b0b4200575fee6f46eca86
apkVersionName: 0.4.1-beta
apkVersionCode: 3028
appHash:        b0d049c45d3ab8bac242779795f330d47f207f44050e1b386f9488ea371feda2

Files /tmp/fromPlay_zapsolutions.zap_3028/apktool.yml and /tmp/fromBuild_zapsolutions.zap_3028/apktool.yml differ
Only in /tmp/fromPlay_zapsolutions.zap_3028/original/META-INF: CERT.RSA
Only in /tmp/fromPlay_zapsolutions.zap_3028/original/META-INF: CERT.SF
Only in /tmp/fromPlay_zapsolutions.zap_3028/original/META-INF: MANIFEST.MF

That’s how it should look like to give it the verdict: reproducible.

About the app

This app is a remote control for lnd, the lightning network daemon. As such it is not exactly a wallet in the sense of many other wallets here as the lnd connected to, also has control over the funds but in a setup where you connect to your own lnd, Zap gets into the position of being able to steal your funds. If you have strong objections with the classification as a wallet, please open an issue on our GitLab.


Verdict Explained

The binary provided was reproducible from the code provided.

As part of our Methodology, we ask:

Does the app we built differ from what we downloaded? If not, we tag it Reproducible  

If we can reproduce the app we downloaded from the public source code, with all bytes accounted for, we call the app reproducible. This does not mean we audited the code but it’s the precondition to make sure the code has relevance for the app.

If the provider puts your funds at risk on purpose or by accident, security researchers can see this if they care to look. It also means that inside the company, engineers can verify that the release manager is releasing the app based on code known to all engineers on the team. A scammer would have to work under the potential eyes of security researchers. He would have to take more effort in hiding any exploit.

“Reproducible” does not mean “verified”. There is good reason to believe that security researchers as of today would not detect very blatant backdoors in the public source code before it gets exploited, much less if the attacker takes moderate efforts to hide it. This is especially true for less popular projects.