Systems 100; devices 110, 120, 130, 150, 160; methods 2400, 2500; and machine-executable programming structures stored in persistent (i.e., non-transitory), computer-readable media 604, 606, 618, 126, 139 for the rapid and secure negotiation, authorization, execution, and confirmation of multi-party data processes, including payment transactions conducted between purchasers 190 having electronic access to bank accounts and other sources of payment, merchants operating e- and/or m-commerce transaction systems 132, 134, 136, and banks and other financial institutions 120 capable of electronically communicating with both.