Information Security Conference (ISC 2008) Day 1

The 11th Information Security Confernce (ISC 2008) was held in Teipei, Taiwan. This is a short summary of some presentations I attended.

Marcel Winandy: Property-Based TPM Virtualization

This was actually my presentation. See my older post and my slides

Endre Bangerter: A Demonstrative Ad Hoc Attestation System

The proposal is to use a trusted device for ad hoc attestation of computing platforms, i.e., showing to the user "PC is ok" or "PC is not ok". It is a server-based approach, where the server sends remote procedure call (RPC) to the PC, and the PC displays flickering barcods on the screen. The trusted device is hold in front of the screen and receives the RPC, i.e., decodes the barcode. Finally, the device displays whether PC is OK nor not.

The decision the device displays is actually based on a remote attestation done between the server and the PC. The trusted device is just used as local "trusted display" of the remote server. For each attestation, the flickering barcode will be different (i.e., includes a counter value) to prevent simple replay attacks. (slides)

Hans Löhr: Property-Based Attestation without a Trusted Third Party

This is an improved protocol for property-based attestation. Instead of having a Trusted Third Party (TTP) issuing certificates for properties, the verifier has a-priori a list of configurations. The attestee creates a proof that its configuration is within a defined list of configurations, without revealing which exact configuration it has. The proof is based on group signatures (ring signature scheme) without revealing the secret key used to sign the commitment. (slides)

Xuhua Ding: An Efficient PIR Construction Using Trusted Hardware

Paper about private information retrieval. Improves reshuffeling of database form O(n) to O(sqrt(n)). Records are colored black and white. On each query, they fetch two records of different colors. Retrieved records are colored black. Shuffeling is done only on black ("touched") records. (slides)

Charalampos Papamanthou: Athos - Efficient Authentication of Outsourced File Systems

Outsourced filesystems means they are stored on a server. The server is completely untrusted (i.e., there is no trusted hardware on the server side). Accessing the files are queries to the server, and accompanied by a "proof" of authenticity, both for file system content and hierarchy. This proof is based on cryptographic hashing, and uses authenticated skip lists and authenticated dynamic trees. It is an efficient scheme (similar to Merkle hash trees), the client only has to maintain a O(1) trusted storage. Query operations have O(k log n) time. (slides)