Help spread awareness for build reproducibility
Please help us spread the word discussing transparency with Lumi Crypto Bitcoin Wallet 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 ¶
Update 2021-06-16: Something weird is going on. Apparently there are three Lumi apps:on the App Store, another on the Play Store: and this one here. The first two are defunct.
Update 2020-06-15: Following a conversation on Twitter we checked again and also added statements of being Open Source and our take on those.
The description on their Play Store listing gets straight to the point:
With Lumi Wallet, you are the only one in charge of your funds. Your private keys are stored on your device, and the funds are protected with a 12-word mnemonic.
So they are not custodial but can we verify this?
On their website we find no link to the wallet’s source code although they claim:
Open-source We’re ready to prove our reliability that’s why our code is publicly available.
In their FAQ we find:
Is Lumi open-source?
Open-source is one of the major concepts in the cryptocurrency space as the whole industry basically grew up on it. Nowadays, building a crypto project without publishing at least a part of your code on GitHub is considered to be bad manners.
We are proud to say that our core wallet technology is open-source. You can view the libraries (for Android, iOS and Web) that we use to generate private keys and sign the transactions.
We use these libraries in our apps and in the web version of the wallet. You are welcome to see and review it anytime via this link.
Public source is not about good or “bad manners”. and “publishing at least a part of your code” achieves nothing at all in terms of security of the app in Google Play.
“We are proud to say that our core wallet technology is open-source.” … this in turn is indeed something to proudly announce: The code they have on GitHub is not only public but also Open Source. Their
lumi-android-core for example is released under the very permissive MIT license. Kudos to their contribution!
For peace of mind that the wallet doesn’t contain backdoors though, publishing libraries that are used by the wallet, without also publishing the wallet’s code itself is not enough and until that code is public at least under a less permissive license, we have to remain with our verdict: not verifiable
Without public source of the reviewed release available, this app cannot be verified!
As part of our Methodology, we ask:Is the source code publicly available? If not, we tag it
A wallet that claims to not give the provider the means to steal the users’ funds might actually be lying. In the spirit of “Don’t trust - verify!” you don’t want to take the provider at his word, but trust that people hunting for fame and bug bounties could actually find flaws and back-doors in the wallet so the provider doesn’t dare to put these in.
Back-doors and flaws are frequently found in closed source products but some remain hidden for years. And even in open source security software there might be catastrophic flaws undiscovered for years.
An evil wallet provider would certainly prefer not to publish the code, as hiding it makes audits orders of magnitude harder.
For your security, you thus want the code to be available for review.
If the wallet provider doesn’t share up to date code, our analysis stops there as the wallet could steal your funds at any time, and there is no protection except the provider’s word.
“Up to date” strictly means that any instance of the app being updated without the source code being updated counts as closed source. This puts the burden on the provider to always first release the source code before releasing the app’s update. This paragraph is a clarification to our rules following a little poll.
We are not concerned about the license as long as it allows us to perform our analysis. For a security audit, it is not necessary that the provider allows others to use their code for a competing wallet.
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