First off, the device can be used as a hot or cold wallet system by locking in a single address the tag is allowed to sign transactions to and from.It also can function as a debit card when paired with NFC-enabled devices. Once compatible POS terminals crop up – software updates for this compatibility are also forthcoming – the tag would provide the functionality of a debit card.If HTML5 browsers incorporate NFC, users could even carry out e-payments with the touch of the key tag.Key tag owners can lay down a variety of transaction rules. Among them, users can require a password, establish a maximum transaction amount, or feed it any number of whitelisted spending addresses.Some Inside DetailsAn ECDSA signature takes approximately 0.2 to 0.6 seconds to sign. The tag wakes up when the presence of a NFC-supported device enters its field. A green LED flashes if the transaction is authorized, if not, it transmits an error to the host and flashes red.Over the course of the device’s life, it could sign approximately 80,000 transactions.The tag can function without a battery, but it includes a battery and clock to enable time-dependent transactions. It could potentially support advanced features like multi-signature wallets and hierarchical deterministic wallets.The white paper warns of potential attack vectors like side-channel attacks, electron microscopes, and NSA backdoors.“Beyond Bitcoin”Peter designed the signing tag with deeper goals in mind. He said:“I want people to think about it less like a bitcoin wallet and more like a general-purpose key. […] I think there is a big future for ECDSA signing tags, far beyond bitcoin. A single Sigsafe tag could unlock the doors to your home, authenticate you to your Gmail account, act as a loyalty card at a grocery store.”Although storage and easy transactions are the short-term uses, the key tag could build intuition for something more disruptive.Sigsafe transaction images via Sigsafe.NFCsecure storagesigsafetransactionsOriginal author: Alyssa Hertig