The present invention provides a payment system that allows a mobile communications device (MCD) to interact with a merchant processing device (MPD) and a payment engine. A communications component associated with the payment engine can send requested barcodes to the MPD, receive barcodes or alphanumeric Universal Product Codes from customer MCDs, and handle payment authorizations and settlements. A barcode management component can generate and interpret barcodes based upon merchant offerings and client requests. A security algorithms component can employ an offset pair algorithm to convert each digit from a payment card information into an offset pair of digits to facilitate security in accordance with one embodiment of the present invention.