A portable token device is described, the token device useable to request transactions performed over an interchange system. The token device authenticates a user through the use of biometric data such as a fingerprint. When in proximity to a point of sale (POS) terminal, the token device communicates with the POS terminal over a wireless network to authorize a transaction involving the user. The interchange system employs blockchain elements that can be used in a payment apparatus for managing payments or other types of transactions, and for managing user accounts. The interchange system enables users to enroll in the system, and enables the various users' computing devices to be used as confirmation centers for new transactions and/or funds transfers between users.