Abstract: A method of controlling access to a resource (140) using a verifying device (130). A watermarking device (110) embeds an authorization code in a signal (120) using watermarking technology. The watermarked signal (120) is then transmitted to a verifying device (130), e.g. as a television or radio program or as a commercial related to the resource (140). In the verifying device (130), the authorization code is extracted from the watermarked signal (120) and an operation to be performed on the resource (140) is authorized in dependence on the extracted authorization code. Preferably the authorization comprises permission for executing a program (231), rendering and/or copying a multimedia object (213) or for activating a cheat function in an electronic game (220).