TAPI: Transactions for Accessing Public Infrastructure
This paper describes TAPI, an offline scheme intended for general Internet-based micropayments. TAPI, which extends and combines concepts from the KeyNote Microchecks and OTPCoins architectures, encodes risk management rules in bank-issued users' credentials which are in turn used to acquire small valued payment tokens. The scheme has very low transaction overhead and can be tuned to use different risk strategies for different environments and clients. Traditional electronic payment systems impose a low bound on the value of each transaction due to the associated processing and clearing overhead. For small-value transactions, this overhead dominates the value of the transaction itself, making the use of such a system uneconomical.