USC CSci599 Trusted Computing Lecture Three – Software Basis for TC January 26, 2007

1. USC CSci599Trusted ComputingLecture Three – Software Basis for TCJanuary 26, 2007 Dr. Clifford Neuman University of Southern California Information Sciences Institute

2. Prelim Project 1A • Pick an application that could benefit from the use of trusted computing. • Prepare 5-15 slides explaining the benefits for the application to use trusted computing and describing how trusted computing provides those benefits. OR

3. Prelim Project 1B OR • Pick an function critical for trusted computing. • Prepare 5-15 slides explaining the purpose of the function and how it is implemented or would be implemented within an operating system or hardware platform. OR

4. Prelim Project 1B OR • Pick an OS that has support for Trusted Computing. • Prepare 5-15 slides explaining how the OS provides important TC functions. What is the underlying basis for the trust, and how do applications use the functionality.

5. Software Basis for Trusted Computing • Last week we discussed the hardware base – the TPM. • This week we look at the requirements within an operating system for Trusted Computing.

6. OS Concepts • Trusted computing base • Trusted path • Separation of processes

7. The Trusted Computing Bases (TCB) • That part of the system which is critical for security. • Vulnerability of the TCB affects the core security of the system. • Trusted Computing Extends the TCB across physical system boundaries. • Allows remote components to be part of the TCB for a particular function.

8. Trusted Path • Provides attestation of the system to the user. • Requires confidence in the hardware by the user. • Requires training of the user on how to invoke trusted path.

9. Separation of Processes • Allows process that are trusted to run without interference from other processes. • Requires isolation that is provided by lower level trusted modules. • Include hardware support, much of which is already standard in chips, but some which is not.

10. Vista Security Technologies • Summary of some of the support for trusted computing in Vista (on the following slides)

11. Trusted Platform Module (TPM)? Smartcard-like module on the motherboard that: • Performs cryptographic functions • RSA, SHA-1, RNG • Meets encryption export requirements • Can create, store and manage keys • Provides a unique Endorsement Key (EK) • Provides a unique Storage Root Key (SRK) • Performs digital signature operations • Holds Platform Measurements (hashes) • Anchors chain of trust for keys and credentials • Protects itself against attacks TPM 1.2 spec: www.trustedcomputinggroup.org Slide From Steve Lamb at Microsoft

12. Why Use A TPM? • Trusted Platforms use Roots-of-Trust • A TPM is an implementation of a Root-of-Trust • A hardware Root-of-Trust has distinct advantages • Software can be hacked by Software • Difficult to root trust in software that has to validate itself • Hardware can be made to be robust against attacks • Certified to be tamper resistant • Hardware and software combined can protect root secretsbetter than software alone • A TPM can ensure that keys and secrets are only available for use when the environment is appropriate • Security can be tied to specific hardware and software configurations Slide From Steve Lamb at Microsoft

13. VEK Disk Layout & Key Storage Windows Partition Contains • Encrypted OS • Encrypted Page File • Encrypted Temp Files • Encrypted Data • Encrypted Hibernation File • Where’s the Encryption Key? • SRK (Storage Root Key) contained in TPM • SRK encrypts VEK (Volume Encryption Key) protected by TPM/PIN/Dongle • VEK stored (encrypted by SRK) on hard drive in Boot Partition SRK 2 1 Windows Slide From Steve Lamb at Microsoft 3 Boot Boot Partition Contains: MBR, Loader, Boot Utilities (Unencrypted, small)

14. BitLocker™ ArchitectureStatic Root of Trust Measurement of early boot components Slide From Steve Lamb at Microsoft

15. Vista co-existence BitLocker encrypts Windows partition only You won’t be able to dual-boot another OS on the same partition OSes on other partitions will work fine Attempts to modify the protected Windows partition will render it unbootable Replacing MBR Modifying even a single bit Slide From Steve Lamb at Microsoft

16. More on Vista signatures Don’t confuse hash validation with signatures Slide From Steve Lamb at Microsoft

17. Code integrity non-goals Protecting from attackers with physical access Verifying the integrity of NTLDR Requires secure startup on TPM-enabled machines Requires read-only fixed media otherwise Supporting rebinding or hotpatching These change the on-disk image CI will work if patch includes updated hash Boot-time checks for revocation lists Slide From Steve Lamb at Microsoft

18. More on Vista Loading New Super-Secret feature in 64 bit version of Vista (not TC related, but useful to know) System files load at random locations in memory. Uses no-execute feature in 64 bit chipsets.

19. Linux and Trusted Computing An IBM research project based Foundations are TPM and Linux Security Modules Provides TPM based trusted boot Authenticated File Metadata Also supports mandatory access controls

20. Linux and Trusted Computing Future plans include Integration with SELinux Integration with Xen Integration with encrypted file systems.