Class 9Physical Security and DRM

CIS 755: Advanced Computer SecuritySpring 2014

Eugene Vasserman

http://www.cis.ksu.edu/~eyv/CIS755_S14/

Administrative stuff

• Project proposal due today (2 pages)

• Quiz II and Exam I pushed back slightly–Quiz II next week

News! News!static OSStatus SSLVerifySignedServerKeyExchange(SSLContext *ctx, bool isRsa, SSLBuffer signedParams, uint8_t *signature, UInt16 signatureLen) { OSStatus err; ... if ((err = SSLHashSHA1.update(&hashCtx, &serverRandom)) != 0) goto fail; if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail; if ((err = SSLHashSHA1.final(&hashCtx, &hashOut)) != 0) goto fail; ...fail: SSLFreeBuffer(&signedHashes); SSLFreeBuffer(&hashCtx); return err;}

Trusted computing base (TCB)

• Software-level TCB• Hardware-enforced software constraints• Hardware-level TCB• TPM:

Physical security

• Why use physical security?–Do Kerckhoffs’ principle or Shannon’s maxim

apply?

• Tamper evidence• Tamper resistance• Properties? Differences?• Assumptions? Trade-offs?• Real-world examples

Blu-Ray DRM References

• “Broadcast encryption”• An Overview of the Advanced Access Content

System (AACS). Henry, Sui, and Zhong. Technical report, 2007.

http://cacr.uwaterloo.ca/techreports/2007/cacr2007-25.pdf

• Revocation and Tracing Schemes for Stateless Receivers. Naor, Naor, and Lotspeich. Crypto, 2001.

http://www.iacr.org/archive/crypto2001/21390040.pdf

Decryption

Figure from the Overview tech report

Efficient keying and revocation

Figures from the Overview tech report

Questions?

Reading discussion