Wallet Logo

Cyclebit Tangem Card

🔍 Last analysed 29th April 2022 . Bad Interface

Jump to verdict 

Help spread awareness for build reproducibility

Please help us spread the word discussing build reproducibility with Cyclebit Tangem Card  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.

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.

What is a bearer token?

Bearer tokens are meant to be passed on from one user to another similar to cash or a banking check. Unlike hardware wallets, this comes with an enormous "supply chain" risk if the token gets handed from user to user anonymously - all bearer past and present have plausible deniability if the funds move. We used to categorize bearer tokens as hardware wallets, but decided that they deserved an altogether different category. Generally, bearer tokens have these attributes:

  • secure initial setup
  • tamper evidence
  • balance check without revealing private keys
  • small size
  • low unit price
  • either of ...
    • somebody has a backup and needs to be trusted
    • nobody has a backup and funds are destroyed if the token is lost/damaged

The Analysis 

Product Description

Cycle Card is a ‘cold storage’ wallet with high-grade hardware protection, developed by Tangem. Non-retrievable private keys prohibit the replication of the card and assets stored on it

The product was developed in tandem with Tangem, which offers similar devices:

Each Cycle Card is bound to a one-off depersonalized wallet address on the blockchain without any personal accounts or private servers. Backed by 100% uptime and an unblockable P2P network of all blockchain nodes.

It can be paired with the Cycle Wallet which is available in Android and iOS

Analysis

This is a Tangem branded offering which can be used by retailers together with Cyclebit’s point of sale solution. Just like other Tangem products listed above, the card does not have a display or an interface.

(dg)

Verdict Explained

The design of the device does not allow to verify what is being signed!

As part of our Methodology, we ask:

Can the user verify and approve transactions on the device? If not, we tag it Bad Interface!

These are devices that might generate secure private key material, outside the reach of the provider but that do not have the means to let the user verify transactions on the device itself. This verdict includes screen-less smart cards or USB-dongles.

The wallet lacks either an output device such as a screen, an input device such as touch or physical buttons or both. In consequence, crucial elements of approving transactions is being delegated to other hardware such as a general purpose PC or phone which defeats the purpose of a hardware wallet.

Another consquence of a missing screen is that the user is faced with the dilemma of either not making a backup or having to pass the backup through an insecure device for display or storage.

The software of the device might be perfect but this device cannot be recommended due to this fundamental flaw.

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.