Frequently Asked Questions about Census Note

Frequently Asked Questions about Census Note

What is a Census Note ?

A Census card is a branded, highly secure hardware cold wallet made to store Bitcoin. With an NFC-enabled phone, you can verify your balance and send your Bitcoin if you want to move them to another wallet.

What makes a Census Card different?

It is guaranteed to never disclose the private key. Handing a card over, is by nature, an off-chain payment transaction. One can sell it as merchandise, send it as a gift, or use it to make a payment. Essentially, it's a secure, smart banknote for Bitcoins

What’s a Census Card like?

A Census Card is a durable plastic card with only one element. This element is a secure chip that holds the funds and the private key. The chip has the NFC antenna that allows you to check the balance and transfer your funds with an NFC-enabled phone. 

  • Contains $0 in BTC value upon delivery
  • 85.60 mm x 45.00 mm x 0.80 mm
  • Embedded EAL6+ SecurCore microchip from Samsung
  • Uses 3DES, AES, RSA, & ECC cryptography
  • Arm SecureCore SC000 Processor
  • Compatible with Android 5.1+ or iPhone with NFC (iPhone7 and above)
  • Firmware audited by Kudelski Security to ensure your protection
  • Original Census design
  • Maintain complete custody & security of your Bitcoin (BTC)
  • Store bitcoin in a convenient, easy-to-use card
  • Tap card to phone using NFC to easily manage assets with the Census App
  • Fully reusable

What cryptocurrencies can a Census Note hold?

At the moment, Census card supports only bitcoin.

How do you buy a Census Note?

Online: order unloaded cards at

We accept all major credit cards and cryptocurrencies.

Security and Technical info

Who knows the private key?

Each Census card holds a secure chip that allows you to store and carry digital assets. The private key is generated by and permanently embedded into the chip. Nobody has access to it either during or after the manufacturing process. This means that nobody can import, export or make a copy of this key.

How can I backup the private key?

You can neither import the private key into a Census Note nor export the private key -- so it’s completely impossible to have a copy. The architecture of each Tangem Note guarantees the chip inside is the only place in the universe where the unique key is located.

How can I be sure that Tangem is secure?

The security of Tangem is audited by the Kudelski Group, a listed Swiss security company. The full report is available here.

After the audit, the chip firmware cannot be modified even by Census. Its intactness in each Note can be verified by an end-user right in the mobile application. The latter exists in open source together with the NFC communication protocol of the Note.

What if somebody scans my Note and transfers the funds from it?

Not to worry - nobody will be able to transfer funds from your Note just by scanning it. Although checking the funds takes seconds, transferring them requires you to hold the Note against your phone for about one minute.

This is a security measure that can be overridden by enabling a PIN-code on the Note (available on demand).

What if I lose a Census Note or somebody steals it?

As with traditional banknotes, a Census Note has to be kept physically secure at all times. The whole cryptocurrency value is always on the chip inside and cannot be accessed without the Note.

If you lose a Census Note, you lose the value. That’s why we don’t recommend loading a large amount (less than USD500) of funds to the Note.

What if a Census Note stops working?

The electronics inside Census Notes are designed to have incredible resilience against attacks and wear. On top of that, every single Note undergoes comprehensive testing during and after manufacturing.

Every time you validate a Census Note, it checks the internal consistency. It will ask you to extract its value at the slightest suspicion of something going wrong.

Tangem’s internal standard has less than one failure case per billion Notes. Independent lab test results are available publicly and upon request.

While Census makes no further warranties, you can mail your Census Note to our offices around the world. If our labs are able to extract the value or determine that there was a loss of value due to an unknown manufacturing defect, we’ll work with you directly on a case by case basis.