Bitkey
Bitkey is a bitcoin-only wallet system from Block, Inc. that replaces the seed phrase with a 2-of-3 multisig split between a phone app, a hardware device and a Block server.
What Is Bitkey?
Bitkey is a bitcoin-only hardware wallet system made by Block, Inc. It combines a phone app, a small hardware device and a server run by Block. The current device has an OLED touchscreen and a fingerprint sensor and talks to the phone only over NFC; its USB-C port is for charging.
There is no seed phrase. Every Bitkey wallet is a fixed 2-of-3 multisig: an App Key on the phone, a Hardware Key that is generated on the device and never exported, and a Server Key held by Block. Any two keys can sign, and Block states that it cannot move funds without one of the customer's keys.
Recovery tools take the place of a written backup. The App Key is stored, encrypted, in iCloud or Google Drive. A lost key is replaced after a waiting period called Delay & Notify, Recovery Contacts can help decrypt the backup, and an Emergency Exit Kit is designed to move funds if Block is unavailable.
The trade-offs follow from that design. Ordinary recovery and inheritance depend on Block's server and on one cloud account. The app handles on-chain bitcoin only, in English, with no desktop version, and its analytics cannot be switched off. Firmware, app and server code are published under the MIT licence, but outside parties cannot yet reproduce the firmware builds.
A Bitcoin-only wallet is a cryptocurrency wallet that supports only Bitcoin (BTC), excluding other cryptocurrencies like Ethereum or altcoins.
Read full definition: Bitcoin-Only WalletA hardware wallet is a dedicated device that keeps private keys offline and signs transactions internally, so the keys never reach an internet-connected computer or phone.
A touchscreen display is a screen that allows users to interact with a device by touching the surface, commonly used in hardware wallets for easy navigation and transaction confirmation.
Read full definition: Touchscreen DisplayBiometric authentication unlocks a wallet with a fingerprint or face instead of, or alongside, a PIN.
Read full definition: Biometric AuthenticationNFC Connectivity in cryptocurrency enables contactless transactions using near-field communication, allowing users to sign or authorize actions by tapping their device to a reader.
Read full definition: NFC ConnectivityUSB-C connectivity means a hardware wallet has a USB Type-C port for a wired connection to a computer or phone, and on many models for power or charging.
Read full definition: USB-C ConnectivityA mnemonic phrase is a set of words that stores a cryptocurrency wallet's private keys, allowing users to recover access if lost.
Read full definition: Mnemonic PhraseMultisig (multi-signature) is a security feature that requires multiple private keys to authorize a transaction, enhancing protection against unauthorized access in blockchain networks.
Read full definition: MultisigRecovery is the process of restoring access to a cryptocurrency wallet using its seed phrase or mnemonic backup if the original wallet is lost or inaccessible.
Read full definition: RecoveryA backup in cryptocurrency is a secure copy of a wallet's seed phrase or private keys. It enables recovery of funds if the original wallet is lost or damaged.
Read full definition: BackupBitcoin (BTC) is the first decentralized cryptocurrency, launched in 2009. It uses blockchain technology for secure, peer-to-peer digital transactions without intermediaries.
Read full definition: BitcoinFirmware is the software that runs on a hardware wallet itself: it generates keys, shows transaction details on the screen and signs.
Read full definition: FirmwareReal-World Examples
Example 1: A Bitkey owner's phone is stolen. On a new phone she restores the encrypted App Key backup from her cloud account and unlocks it with the hardware device, so two of the three keys are available again.
Example 2: The hardware device is lost. The owner starts a recovery in the app, and after the Delay & Notify waiting period Block's server co-signs the move to a new set of keys.
Example 3: Someone who also wants to hold Ethereum needs a second wallet for it, because Bitkey handles on-chain bitcoin only.
A backup in cryptocurrency is a secure copy of a wallet's seed phrase or private keys. It enables recovery of funds if the original wallet is lost or damaged.
Read full definition: BackupRecovery is the process of restoring access to a cryptocurrency wallet using its seed phrase or mnemonic backup if the original wallet is lost or inaccessible.
Read full definition: RecoveryEthereum is a decentralized blockchain platform that enables smart contracts and decentralized applications (dApps). Its native cryptocurrency is Ether (ETH).
Read full definition: EthereumBitcoin (BTC) is the first decentralized cryptocurrency, launched in 2009. It uses blockchain technology for secure, peer-to-peer digital transactions without intermediaries.
Read full definition: BitcoinBitkey hardware wallets
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Frequently Asked Questions
What happens if I lose my phone or the Bitkey device?
Two of the three keys are still enough. If the phone is lost, the encrypted App Key backup is restored from the cloud account onto a new phone and unlocked with the hardware device. If the device is lost, a recovery is started in the app, and after the Delay & Notify waiting period Block's server co-signs the move to a new set of keys.
Can Block move my funds?
Block holds only one of the three keys, and any transaction needs two. Block states that it cannot move funds without one of the customer's keys. Ordinary recovery and inheritance do depend on Block's server, and the Emergency Exit Kit is designed to move funds if Block is unavailable.
Can I back up a Bitkey with a seed phrase instead?
No. Bitkey has no seed phrase; every wallet is a fixed 2-of-3 multisig. Recovery tools take the place of a written backup: an encrypted App Key backup in iCloud or Google Drive, the Delay & Notify process for replacing a lost key, Recovery Contacts and the Emergency Exit Kit. That makes the cloud account an important part of the setup.
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