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Tangem - Crypto wallet

Latest release: 4.0 ( 30th December 2022 ) 🔍 Last analysed 10th April 2021 . No source for current release found
4.8 ★★★★★
71 ratings
28th April 2018

Without public source of the reviewed release available, this product cannot be verified!

As part of our Methodology, we ask:

Is the source code publicly available?

If the answer is "no", we mark it as "No source for current release found".

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 product 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 product’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. You should still prefer actual open source licenses as a competing wallet won’t use the code without giving it careful scrutiny.

The product cannot be independently verified. If the provider puts your funds at risk on purpose or by accident, you will probably not know about the issue before people start losing money. If the provider is more criminally inclined he might have collected all the backups of all the wallets, ready to be emptied at the press of a button. The product might have a formidable track record but out of distress or change in management turns out to be evil from some point on, with nobody outside ever knowing before it is too late.

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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 

This app is the companion app to an NFC card that is promoted as something like a hardware wallet but without a screen or a button it can only do what the companion app - this app - tells it to do. As such, this app is very crucial if you use these cards as your Bitcoin wallet. It has to be trustworthy and thus we consider it a Bitcoin wallet. Our mission is to look for the potential of all the users of an app lose all their funds at once which arguably cannot happen in the given configuration. The app could not collect the private keys from the cards if the cards do what they claim which cannot be publicly verified neither but even if the card does as advertised, the app could still steal a lot of funds of a lot of users if it would switch to evil-mode for all users at once. It would still require users’ interaction but the window of opportunity could easily be days to weeks before Google would remote-wipe the app or the app would get stopped from emptying wallets of unsuspecting users upon their next use.

The description on the App Store is not explaining much and neither does their website explain in clear words what this app is but I found this demo video and it clearly shows that the app is crucial for the security of your funds.

The next question would be: “Is the code public?” … but as far as I can see there is no source code available that one could inspect. That leaves us with the verdict not verifiable.