A METHOD OF GENERATING AND VALIDATING A VOUCHER THAT IS USED TO ENABLE AN END-USER TO OBTAIN GOODS OR SERVICES

摘要

A method of generating and validating a voucher that is used to enable an end-user to obtain goods or services is disclosed. It comprising the steps of: (a) generating or acquiring contextual data that describes the goods or services and then encrypting that contextual data at a server or other device; (b) generating a time code corresponding to or representing a span of time during which the voucher is valid and including or concatenating that time code with the contextual data, either before or after that contextual data has been encrypted; (c) signing the contextual data and time code cryptographically using either a symmetric or asymmetric secret key or keys to generate a signature, in order to prove the origin issuer and time code at the point of generation; (d) providing the contextual data and time code and/or the signature on a voucher, such as a printed voucher or as a virtual voucher shown on or provided using a computing device, such as a smartphone; (e) validating the voucher offline at a validating system, without having on-line access to the server or other device that cryptographically signed the contextual data by means of comparing the signature in a process using a locally stored key shared with the server or other device that encrypted the contextual data.