Is a hardware security key similar to multisig?

Not exactly. Multisig technology is used to sign blockchain transactions. In that scenario, a transaction may require multiple signatures from different private keys before being broadcast to the blockchain.

On the other hand, hardware security keys are part of a strong multi-factor authentication system. They are not directly related to blockchain technology and can be used across various services as a secure form of authentication.

At Xapo Bank, these security keys provide an extra layer of protection by requiring a dedicated physical device to authorise withdrawals from your BTC Vault. Without this technology configured in the account, members can still authorise transactions using biometrics, PINs, and other forms of authentication. However, security keys are widely regarded as the strongest method of authentication available.