A method for synchronizing content pieces on a first device with a second device, characterised in that the method comprises: at the first device, receiving a request from the second device to synchronize content pieces stored on the second device with content pieces stored on the first device; from a set of structures stored on the first device, identifying a first structure (815,820) and a second structure (805, 810) associated with the second device that have not yet been transferred to the second device, the first structure (815,820) comprising a set of device-unrestricted content pieces and a set of verification parameters for authenticating said device-unrestricted content pieces, the second structure (805, 810) comprising a set of encrypted content pieces and a set of content keys for decrypting said encrypted content pieces, wherein the device-unrestricted content pieces require authentication using the verification parameters prior to at least one type of non-playback operation, and wherein the device-unrestricted content pieces do not require authentication using the verification parameters prior to a playback operation; removing at least one content piece from each of the first (815, 820) and second structures (805, 810) that are designated as content pieces that should not be transferred to the second device; for each device-unrestricted content piece removed from the first structure (815, 820), removing the verification parameter associated with the removed device-unrestricted content piece; for each encrypted content piece removed from the second structure (805, 810), removing the content key associated with the removed encrypted content piece; and after removing the designated content pieces and the associated content keys and verification parameters, transferring the first (815, 820) and second structures (805, 810) to the second device. at the first device, receiving a request from the second device to synchronize content pieces stored on the second device with content pieces stored on the first device; from a set of structures stored on the first device, identifying a first structure (815,820) and a second structure (805, 810) associated with the second device that have not yet been transferred to the second device, the first structure (815,820) comprising a set of device-unrestricted content pieces and a set of verification parameters for authenticating said device-unrestricted content pieces, the second structure (805, 810) comprising a set of encrypted content pieces and a set of content keys for decrypting said encrypted content pieces, wherein the device-unrestricted content pieces require authentication using the verification parameters prior to at least one type of non-playback operation, and wherein the device-unrestricted content pieces do not require authentication using the verification parameters prior to a playback operation; removing at least one content piece from each of the first (815, 820) and second structures (805, 810) that are designated as content pieces that should not be transferred to the second device; for each device-unrestricted content piece removed from the first structure (815, 820), removing the verification parameter associated with the removed device-unrestricted content piece; for each encrypted content piece removed from the second structure (805, 810), removing the content key associated with the removed encrypted content piece; and after removing the designated content pieces and the associated content keys and verification parameters, transferring the first (815, 820) and second structures (805, 810) to the second device.