Method for performing a secure cash-free payment transaction and a cash-free payment system

摘要

A method for performing a cash-free payment transaction that comprises: a) a provider (PPPP) receives a pre-authorization message (2′) for a payment to be made by a buyer (B), the pre-authorization message being authenticated for example by a personal identification number; b) the provider (PPPP) generates a payment nonce in response to this pre-authorization message; c) the provider (PPPP) forwards this payment nonce (3′) to the buyer (B) and the provider (PPPP) approves the payment when asked or when being debited by a seller (S′) interface. The method further comprises that the above mentioned steps are performed by a private pre-authorization and payment provider (PPPP) and that the provider (PPPP) accepts a pre-authorization message being sent by a buyer's personal trusted device (PTD) being independent of the seller's interface and that the provider (PPPP) generates the payment nonce in a form which can be read by the seller's interface. This method using a personal trusted device (PTD) to obtain a nonce that protects privacy and prevents fraud being at the same time flexible enough to be used in different kinds of transactions, even in off-line transactions and not requiring downloads, special hardware, certificates, or pre-registration by the buyer.