TangemTangem backup cards
Backup cards hold copies of the same private key for one Tangem Hardware Wallet. A remaining linked device can preserve access when another card is lost or stolen.
- Set Size
- Two or three Tangem devices in total, using cards, a ring, or both.
- Device Roles
- Every linked device provides equal access to the wallet. One device can sign without the other cards present.
- Backup Window
- The private key can be copied to the chosen backup devices only during the one-time backup process. Include the full set before finalization.
Encrypted Key Transfer
Hardware backup starts with mutual authentication between the Tangem devices. They establish a secure communication channel using Diffie-Hellman key exchange and 256-bit encryption. The private key passes between devices through this encrypted channel, and the app cannot decrypt it.
Each device operates independently of Tangem’s servers and the other devices after backup. The one-time copying restriction limits additional copies beyond the chosen set. Allowing repeated backups would make extra copies possible without the owner’s knowledge.
Transaction signing uses a different exchange. The phone sends an unsigned transaction to a linked device over NFC. The device signs internally and returns only the signed transaction.
Offline Setup Prerequisites
For second-generation Tangem Wallets or later, every device needs an initial online scan before offline setup and backup. During that scan, the app downloads the device certificate to verify Tangem manufacture and firmware. The certificate also supports authenticated communication between devices during backup. Scanning one card does not satisfy this prerequisite for the other devices in the set.
Access With a Remaining Card
Hardware wallet access on a replacement phone requires the Tangem app, a linked device, and the wallet’s access code. The phone must support NFC. The surviving card already holds the wallet’s key, so it provides access without a separate primary card. A lost device cannot be blocked. Losing every linked device makes a seedless wallet unrecoverable; a wallet set up with a seed phrase can be restored using that phrase.
Card-based backup applies to Tangem Hardware Wallets. Tangem’s phone-only Mobile Wallet has separate backup methods.
Backup Finalization
A finalized two-device wallet cannot accept a third device through another backup operation. Using three devices requires a new wallet with all three. Move all cryptocurrencies to another wallet or exchange before resetting any linked device. Every device in the existing backup requires its own factory reset.
A Third Card After Finalization
This hypothetical case assumes a funded wallet, a completed two-card backup, and an unused third card from the same set. The owner expects three key copies, but the wallet’s Details screen lists two linked devices.
- Keep the Existing Wallet
- The two linked cards retain access to the existing wallet. The unused third card does not hold its private key.
- Create a Three-Device Wallet
- Move all crypto elsewhere first. Reset both linked devices, then create a new wallet using all three cards. The three devices now hold copies of the new wallet’s key. The moved assets remain at the other destination until transferred again.
Check the new wallet’s Details screen for three linked devices. Merely possessing three cards does not establish three copies of its key. If the initial backup is unfinished, the third device can join before finalization without resetting the wallet.
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