US Patent 8090654 Techniques for transaction adjustment

Techniques are provided for transaction adjustment. A payment device, having an offline balance, is presented to an offline terminal in connection with a putative transaction. If an irregularity with the putative transaction is detected, the offline balance is adjusted responsive to the detection. In one aspect of the invention, such adjustment can be carried out, via offline-terminal interaction, substantially without the use of a security module and cryptographic keys in the offline terminal.