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CoolWallet S

🔍 Last analysed 8th December 2021 . Leaks Keys
1st January 2018

This product requires sharing private key material!

As part of our Methodology, we ask:

Does the device hide your keys from other devices?

If the answer is "no", we mark it as "Leaks Keys".

Some people claim their paper wallet is a hardware wallet. Others use RFID chips with the private keys on them. A very crucial drawback of those systems is that in order to send a transaction, the private key has to be brought onto a different system that doesn’t necessarily share all the desired aspects of a hardware wallet.

Paper wallets need to be printed, exposing the keys to the PC and the printer even before sending funds to it.

Simple RFID based devices can’t sign transactions - they share the keys with whoever asked to use them for whatever they please.

There are even products that are perfectly capable of working in an air-gapped fashion but they still expose the keys to connected devices.

This verdict is reserved for key leakage under normal operation and does not apply to devices where a hack is known to be possible with special hardware.

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.

Help spread awareness for build reproducibility

Please help us spread the word discussing build reproducibility with CoolWallet S  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.

The Analysis 

Update Verdict 2021-12-08

As the same provider to ECOMI’s Secure Wallet Leaks Keys! , Cool Wallet S requires pairing with a mobile app via Bluetooth. It is through the mobile app where the seed phrases are displayed and not on the hardware device itself.

Thus, in WalletScrutiny’s methodology, it fits the description of having leaky private keys:

the private key has to be brought onto a different system that doesn’t necessarily share all the desired aspects of a hardware wallet.

Previous Analysis 2021-08-28

This device, running weeks on a single charge connects to its companion app on

via Bluetooth. It features a display and a button to confirm actions.

Searching for the firmware, latest updates thereof and the source code, we find this FAQ question:

Which Operating System Is CoolWallet Using?
The core of CoolWallet is an ARM-based secure element. We developed the native card operating system with cryptocurrencies capability and enhanced security features.

which sounds like the firmware probably is closed source.d

The device uses open standards BIP 039, BIP 044 and BIP 141 for SegWit and not BIP 049.

As suspected though …

Why Is The Firmware Not Open Sourced?
We have ongoing Black-Box test teams working to perfecting our codes and we can provide source codes of the Micro-Controller-Unit code and the firmware. However, only the trusted members of the cryptocurrency communities and/or security industry are welcomed to evaluate and audit all of our code and libraries. Thus, if you are interested to see our code, please contact us at support@coolbitx.com for more details. *An NDA (Non-disclosure Agreement) will need to be signed between you and us. This is to ensure that the shared codes are used solely for personal review.

so as we do not claim or want to be the authority and keep all our analysis transparent, we have to stop here and conclude this product is not verifiable.

(ml, lw)