Building Secure, DRM-Enabled Devices

1. Building Secure,DRM-Enabled Devices Avni Rambhia Program Manager John C. Simmons Program Manager Strategic Relations & PolicyWindows Client Division

2. Session Outline • Introduction • The importance of secure DRM implementations • Anatomy of robustness rules – content, assets and security levels • The general threat surface for DRM-enabled devices • The design of secure DRM-enabled devices • Protecting device assets • Device asset threat surface and robustness rules • Robust hardware, firmware and software best practices • Protecting controlled content • Controlled content threat surface and robustness rules • Best practices for robust protection of controlled content • Design pitfalls to be avoided • The secure development environment • Call to action • Questions and answers

3. The Importance Of Secure DRM Implementations • Secure DRM technology is required for access to valued content • Access to valued content can be denied to implementations which do not meet robustness rules • After deployment, access can be revoked for implementations which are shown to violate robustness rules • The robustness requirements for DRM-enabled devices are likely to increase with the value of deployed content

8. Robust Hardware-Firmware Best Practices • Robust hardware design • Put critical data bus traces below the surface of the board • Use a highly-integrated chip design or high-density packaging • Use on-chip RAM to secure keys during decryption • Use a CPU that supports segment-level cache locking • Support the use of a Smart or SIM card • Use chassis tamper-detecting hardware • Robustness and manufacturability • Disable all on-chip debugging resources in production • Do not run Security Functions with JTAG-enabled hardware • Cover Test Points with Epoxy • Robustness and device tamper-resistance • Establish a secure platform, based upon one strong root of trust • Extend chain of trust to the software applications running on the device • Don’t run security functions if environment does not match production specifications

9. Robust Software DesignBest Practices • Robust software design • Use high resolution performance timer to detect kernel level debuggers • Link select C runtime code directly into your binary • If keys must be held in virtual memory, lock the key in memory • Minimize the time that secrets are kept in the clear in memory • Verify compiler optimizations do not undo your buffer zeroing operations • Scrub memory which has contained secrets before passing to free() • Robustness and device key concealment • De-randomize key information when obfuscating it in storage • Ensure that the obfuscation algorithm is one-way • Obfuscate key information in a binary object at least 1 KB in size • Robustness and the product life cycle • Use a program obfuscation tool to frustrate reverse engineering attempts • Exclude private key concealment software from pre-release devices • Enforce physical access and security rights to all code during production

11. Best Practices For Robust Protection Of Controlled Content • Integrate components whenever feasible • If asset must flow over a bus • Provide cryptographic protection to the asset (not 'unprotected') • Provide structural protection to the bus (not 'accessible') • Minimize vulnerability to peripheral attacks. Examples • use non-paged memory when feasible • use design with on-chip RAM whenever feasible • do not buffer structured cleartext compressed content to one memory chip • minimize time for which clear asset is in process memory • Provide layered protection for assets in storage • Layer 1: Cryptographically protect the content key • Layer 2: Obfuscate the secret which protects the license • Layer 3: Obfuscate the code which extracts this secret

12. Design Pitfalls To Be Avoided • Not verifying/tamper-protecting root public keys • Not protecting the key that protects the key • Seeding a robust pseudo-random number generator with poor entropy • Ignoring bus vulnerabilities in a System-on-Chip design • Not incorporating threat modeling as part of thedesign process • Designing to today’s industry requirements/constraints, without consideration of the future • Not incorporating security into the development and manufacturing process

13. Secure Development Environment • Enforce physical access and security rightsto security code • Access and use policy around secure code • Secure lab for Device key development • Control access to Device key design documentation • Control access to Device key source code • Build the Device key software on a secure machine • Manufacturing security • Never expose device secrets in the manufacturing environment • Make sure repair instructions do not inadvertently leakconfidential information • Ensure mechanical restrictions imposed by Robustness rules are met by post-repair devices

14. Call To Action • Understand all compliance and robustness rules requirements for your device before beginning thedesign process • For example, the compliance and robustness rules for Microsoft’s next generation Windows Media DRM for Portable and Network Devices • Anticipate future trends in robustness requirements by discussing with Microsoft, content providers, andchip manufacturers • Perform threat modeling at all stages of the design process – make asset protection and content protection integral to your design process • Audit your development environment and manufacturing process for vulnerabilities

15. Additional Resources • Email • Secdrm @ microsoft.com • Web Resources: • WM DRM Web Site: http://www.microsoft.com/windows/windowsmedia/drm.aspx • WM DRM Partners • http://www.microsoft.com/windows/windowsmedia/drm/9series/providers.aspx • Windows Media Community • http://www.microsoft.com/windows/windowsmedia/community.aspx • Windows Media DRM Newsgroup • news://msnews.microsoft.com/microsoft.public.windowsmedia.drm • Related Sessions • Business Opportunities with WM DRM (SW04004) • Designing Portable Media Players for Windows (TW04050) • Media Transfer Protocol (TW04083) • Windows Media Connect (TW04081) • Certified Output Protection Protocol (TW04066) • Next Generation Windows Media DRM for Consumer Electronics Devices (TW04014)

16. Community Resources • Community Sites • http://www.microsoft.com/communities/default.mspx • List of Newsgroups • http://communities2.microsoft.com/communities/newsgroups/en-us/default.aspx • Attend a free chat or webcast • http://www.microsoft.com/communities/chats/default.mspx • http://www.microsoft.com/seminar/events/webcasts/default.mspx • Locate a local user group(s) • http://www.microsoft.com/communities/usergroups/default.mspx • Non-Microsoft Community Sites • http://www.microsoft.com/communities/related/default.mspx