Abstract: A method of securely processing a transaction includes storing a plurality of encrypted financial transaction instrument identifiers in a memory wherein there is no decryption key for these stored in the memory and further wherein the encrypted financial transaction instrument identifiers are each associated with a mobile communications device. Receiving at a server a request to process a transaction, the request including an identification of a mobile communications device. Retrieving from the memory the encrypted financial transaction instrument identifier associated with the mobile communications device identified in the request. Transmitting the retrieved encrypted financial transaction instrument identifier to the mobile communications device. Receiving from the mobile communications device transaction data and using the received transaction data to effect a financial transaction.