A method for a first software application on a computing device to access a DRM client on the computing device, the computing device comprising an input device for receiving a user input, the first software application not being configured to interface directly with the DRM client, the computing device including a media player application configured to directly interface with the DRM client, wherein the DRM client is only directly accessible via one or more predetermined access applications, the one or more predetermined access applications including the media player application but not including the first software application, the method comprising steps of: (a) the first software application sending DRM-protected content to the media player application to thereby cause the media player application to access the DRM client for decrypting the DRM-protected content so as to enable rendering of the DRM-protected content by the media player, wherein the DRM-protected content is received by the first software application from a server connected to the computing device by means of a network, wherein the DRM client is executing in a secured module configured to prevent and/or restrict other software applications not belonging to the one or more predetermined access applications executing on the computing device from accessing the DRM-protected content, and wherein the DRM-protected content comprises audio and/or video challenge content comprising a challenge having an associated predetermined response; (b) receiving, by the server, a user input from the input device in response to the rendering of the challenge content on the computing device; (c) comparing, by the server, the received user input with the associated predetermined response so as to verify whether the first software application is interacting with a human end user; (d) sending, by the server, a verification message indicating the result of the comparison to the first software application; and (e) based on the verification message, determining, by the first software application, whether to continue execution of the first software application. (a) the first software application sending DRM-protected content to the media player application to thereby cause the media player application to access the DRM client for decrypting the DRM-protected content so as to enable rendering of the DRM-protected content by the media player, wherein the DRM-protected content is received by the first software application from a server connected to the computing device by means of a network, wherein the DRM client is executing in a secured module configured to prevent and/or restrict other software applications not belonging to the one or more predetermined access applications executing on the computing device from accessing the DRM-protected content, and wherein the DRM-protected content comprises audio and/or video challenge content comprising a challenge having an associated predetermined response; (b) receiving, by the server, a user input from the input device in response to the rendering of the challenge content on the computing device; (c) comparing, by the server, the received user input with the associated predetermined response so as to verify whether the first software application is interacting with a human end user; (d) sending, by the server, a verification message indicating the result of the comparison to the first software application; and (e) based on the verification message, determining, by the first software application, whether to continue execution of the first software application.