You may have seen photos of these Cardano-branded Tangem cards online or even received one at the IOHK Summit, so here’s a bit more information about them! Tangem cards are hardware wallets, in the form of a card, made to store your crypto funds that works with NFC-enabled phones. It is guaranteed not to ever disclose a private key. So handing a card over is by nature an off-chain payment transaction. One can sell it as a merchandise, send it as a gift or pay with it like a banknote.
We’ll be sharing more information about Tangem, and how you can get your hands on one through meetups and giveaways…but for now, here’s how to use them:
How to check validity and balance of Tangem card
Each Tangem card contains only two elements: a secure chip (which holds the funds) and an NFC antenna (which allows to check the validity). If you have ever used Apple or Google pay - you know exactly how to check the validity of Tangem cards and the funds it’s holding. You will just need to open the Tangem app (available on Google Play store here) or Tangem Lite app for iOS (available here) and tap the card to the NFC scanner inside your phone.
Scanning the card takes a second. The apps will verify that the card is genuine, ensure it possesses the correct private key, and obtain the balance from the blockchain. You can always double check it right in the blockchain explorer if needed. From this moment, you can be sure that you are the only holder of private key and funds.
How to load funds to Tangem card
Once the card is scanned and verified, the app will display the exact blockchain address linked to the card and its private key. You can use any other blockchain wallet app to transfer funds to the card from a source wallet. You can also transfer funds from another card using Tangem app.
How to transfer funds from Tangem card
Please note: as the functionality of the NFC in the iOS is limited to read-only, sending data is not allowed. Which means that you can check the validity of the card and the funds it’s holding, but you cannot load or extract them using iPhones. We expect that iOS development will unlock sending data via NFC in the near future. Tangem will update the app to work the same as Android version as soon as this happens.
To extract funds from Tangem card you will need a Tangem card and the Tangem app on an NFC-enabled Android device (available here).
Scan and verify the card as explained above, then tap ‘Extract’ button and prepare the outgoing transaction: define target wallet address, amount, fee. You will be asked to tap and hold the card while it signs the transaction. In the end, the signed transaction will be broadcasted to blockchain. That’s all!
Worried about security? Not to worry - nobody will be able to transfer funds from your card just by scanning it. Though checking of funds only takes seconds, transferring them will require you to hold the card against your phone for about one minute. This is a security measure that can be overridden by enabling a PIN-code on the card.