Sugi🔍 Last analysed 23rd March 2022 . Bad Interface
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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.
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 ¶
The Sugi card is very similar to. It has NFC, has a secure element for authentication and has a companion app. Although it is marketed primarily as a “NFC wallet card”, it can function with the intention of passing it to another user.
Previous Review 2021-08-08
The Sugi card lacks a screen or a button, this device cannot provide basic security of hardware wallets.
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.
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