Content Protection for Optical Media Content Protection for Optical Media A Comparison of Self-Protecting Digital Content and AACS

Our evaluation considered VM specification version 1.0b and Interface Specification 0.95a. We also examined the integration of SPDC with the Advanced Access Content System (AACS) as defined by the AACS public specification revision 0.90 (dated April 14, 2005), along with supplemental slides and materials. We first note several flaws in the current version of the AACS specification, and further examine the implications of device compromise on the security offered by AACS. We conclude that in many instances the SPDC framework offers significant advantages in content protection over AACS alone. Self-Protecting Digital Content. The focus of this report is on the use of SPDC as a core component of a secure digital content distribution system. SPDC provides content creators with a means to author title-specific " content code " for execution at the device. This content code allows for the software re-implementation of player processing logic, in the event that class of devices is compromised or is found to contain exploitable faults. This provides a means to enable renewability even where device hardware cannot be fully trusted. We compare the security offered by SPDC/AACS to the security provided by AACS alone, in scenarios involving device and device-class compromise (e.g., hardware compromise of a single player, or compromise of all players of a given model.) We note that SPDC provides immediate content protection in a variety of compromise scenarios, whereas AACS achieves protection only for future titles (via device revocation). Furthermore, even when considering protection for future titles, device revocation schemes such as AACS do not adequately address the case of device-class compromise. No device-side content protection system can withstand all attacks. We note explicitly that the protection offered by SPDC content code should be considered time-limited. The principal advantage of SPDC is the ability to recover system security, potentially with each new title released. SPDC also provides mechanisms by which content creators can overcome or repair device implementation flaws, and provides a generally more resilient level of system security than can be provided by key management and device-revocation systems alone. Self-Protecting Digital Content (SPDC) architecture. Our evaluation considered the VM Specification version 1.0b and Interface Specification 0.95a. We also examined the integration of SPDC with the Advanced Access Content System (AACS) as defined by the AACS public specification revision 0.90 (dated April 14, 2005), along with supplemental slides and materials. The focus of this report is the use of SPDC as …