There is described a method for a first software application to access a secured software application on a computing device. The first software application is not configured to interface with the secured software application. The computing device includes an interfacing application configured to interface with the secured software application. The method comprises the first software application interfacing with the interfacing application to thereby cause the interfacing application to access the secured software application. The first software application is configured to interface with the interfacing application. There is also described a method of generating an encrypted version of an image using a library of pre-encrypted blocks of data, the same content encryption key having been used to encrypt each of the pre-encrypted blocks of data. The method comprises forming the encrypted version of the image from an ordered sequence of pre-encrypted blocks of data from the library, wherein each pre-encrypted block of data in the ordered sequence corresponds to a respective sub-image of a plurality of sub-images making up the image. There are also described corresponding computing devices, computer programs and computer-readable media.