Cardano 911 — Tangem wallet or NFC-powered hardware cryptobill

When I first saw a Tangem note, I did not appreciate this product. All I thought about:

“There is no seed phrase for wallet backup. It’s not cool.”

But after a while, I realized that backup is not needed. After all, when you use fiat money (banknotes and coins), you don’t think about backup, do you? So if you lost or physically damage Tangem, then you irrevocably lost all ADA that was there — the same way as fiat money.

However, one undeniable advantage makes this card very special — Tangem makes it easy to enter the cryptocurrency world for those who are not tech-savvy.

What’s inside?

There are two components inside: an NFC antenna and a tiny Samsung EAL6+ chip with a proprietary Operating System. That’s all. The chip keeps some math for seeding a private key and then generating a public key using elliptic curve cryptography (ECC) based on Edwards curve.

Tangem Notes are highly secure smart cards carrying cryptocurrencies on a recently developed EAL6+ SecurCore microchip from Samsung Semiconductor. The value can be extracted at any time by signing a transaction from the Tangem Note to an arbitrary Cardano wallet. This requires a compatible NFC–enabled Android phone or iPhone and is protected by a security delay. Faraday wallet is recommended for additional security.Faraday wallet by Output

If the chip is damaged, the private key cannot be restored (there’s no seed phrase, remember?), hence all your funds will be lost. If the antenna is damaged, you can solder it, so all your funds are in safety. Easy.

*Having bought a Tangem card, you have to trust the chip manufacturer because algorithms for generating keys are recorded at a factory in China.

In fact, a chip is considerably smaller because at this image we see not a chip but rather its socket

How does it work?

I tried it on iPhone 12 (on Android, it’s also possible). It sounds strange, but you don’t even need to know the name of the Tangem app in the App Store. You just bring the card to the phone, power will be transferred via NFC, OS will start, and iPhone, using the App Clips feature for iOS, displays the application you need to download on the lower part of a screen. Definitely, it’s an excellent protection against scamming and phishing. So you never download a scam app.

Tip: The app will notify the user if the card has already been used.

To generate a key pair and then create a receiving address, based on public key, you need to marry Tangem card and iPhone (it takes some time to apply a math). Then you can charge your wallet’s balance with ADA. After that, you can only spend money if you have a phone with the installed app and Tangem card.

Your private key is never broadcast to the Cardano network. To send ADA to someone, you just need to sign the transaction. To do this, you have to choose an amount to send, bring the Tangem card to activate the chip, and generate a signature based on your private key.

Tangem for Cardano (Android version)

How many ADA should I store on Tangem?

I think that the amount of stored coins must not be greater than the equivalent of €500. Do not store large amounts of ADA on Tangem. Like in real life, there’s no €14,532 fiat banknote.

Present Tangem to your friend

For those who are not tech-savvy, Tangem is an ideal tool to buy goods using cryptocurrency. It has no password, no mnemonic phrase, no advanced user interface in app. All you can worry about is:

your card is not stolenyour card is not damagedthe attacker does not lean his phone against your card

Specifications

Dimensions: 85.6 x 45 x 0.6 mm
Weight: 3 grams
Processor: Arm SecurCore SC000
Fabrication: 65 nm
Antenna: copper coil, energy harvesting
Interface: NFC ISO 14443 A/B, 13.56 MHz
Cryptography: 3DES, AES, RSA, ECC
Elliptic Curve: edwards25519
Certifications: CCRA EAL6+, EMVCo, IP68, Kudelski Group
Compatibility: Android or iPhone (NFC)

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That’s all for now.

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Cardano 911 — Tangem wallet or NFC-powered hardware cryptobill was originally published in The Capital on Medium, where people are continuing the conversation by highlighting and responding to this story.