Method and system for authorizing a transaction

System for authenticating a transaction, wherein a first transaction party uses a first electronic device for performing said transaction and a second transaction party uses a second, portable, electronic device for performing said transaction, which first device comprises a screen display and which second device is a general-purpose programmable device comprising a digital camera, which system comprises a first transaction software function arranged to be executed on or from the first device or a control device arranged to control the screen display;

• a second transaction software function arranged to be executed on or from the second device;
• and a central server in communication with said first and second software functions, wherein the central server is arranged to associate the transaction with the first device;
• and wherein the first software function is arranged to display, on the screen display, visually coded information identifying the transaction, wherein characterised in that in that the second software function is arranged to capture, using the digital camera, an image of the screen display, which image comprises said visually coded information as well as at least a portion of the first device which portion lies outside of the screen display;
• wherein that the second software function and/or the central server is arranged to decode and interpret said visually coded information, based on the captured image, and further to identify, using image analysis, a geometric shape or metric of a piece of hardware pertaining to the first device also based upon the same captured imaged;
• and wherein the central server is arranged to verify that the transaction identified by the visually coded information is associated with the first device, based upon the identified piece of hardware.