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Zap: Bitcoin Lightning Wallet

latest release: Varies with device ( 6th December 2021 ) last analysed  15th December 2021 Reproducible when tested
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Disclaimer

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:

===== Begin Results =====
appId:          zapsolutions.zap
signer:         24a0e944a65d8cea692653e1a132a042c37be334f1b0b4200575fee6f46eca86
apkVersionName: 0.5.4-beta
apkVersionCode: 3034
verdict:        reproducible
appHash:        32bf9ee5b4e4093c2d50e2a4c3589081745526280c47887e0512f7934392bdcc
commit:         f8263917f934efa77c14ae1a057e5fdacf2d30bc

Diff:


Revision, tag (and its signature):

===== End Results =====

Empty diff? As prior versions did not have an empty diff, we double-checked if our script did something wrong but it’s just that Zap dropped the use of “JAR signing”, using only “APK Signature Scheme v2”:

$ apksigner verify --print-certs -v zapsolutions.zap_3032_f248710d319b11e37bc805fc7dbd5c27043a9a212f4359847126797d7af25757.apk | grep using
Verified using v1 scheme (JAR signing): true
Verified using v2 scheme (APK Signature Scheme v2): true
Verified using v3 scheme (APK Signature Scheme v3): false
$ apksigner verify --print-certs -v zapsolutions.zap_3033_ab73d13b45ef0f20d43030a2fb00b64b280546307dc48bf95efd2d1aebabe9b4.apk | grep using
Verified using v1 scheme (JAR signing): false
Verified using v2 scheme (APK Signature Scheme v2): true
Verified using v3 scheme (APK Signature Scheme v3): false

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.

(lw)

Verdict Explained

The binary provided was reproducible from the code provided.

As part of our Methodology, we ask:

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

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

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 product 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.