Secrecy Preserving Signatures Filtering Packets without Learning the Filtering Rules

2 Preventing Attacks with Filtering Inbound Traffic Filtered Traffic Blocked Traffic Commodity FW Threat Signatures

3 Problem: Protecting IP Inbound Traffic Filtered Traffic Blocked Traffic Commodity FW Threat Signatures Valuable/Sensitive Information

4 Solutions Inbound Traffic Filtered Traffic Blocked Traffic Commodity FW Threat Signatures Valuable/Sensitive Information Option #1: “Lock the Door” The signature owner performs all filtering. The third-party network operators improve their physical security. We encase the hardware in tamper-resistant cases.

5 Solutions Option #2: Distribute the Signature Information No single machine knows the signatures or can, by itself, determine whether a packet would be filtered. Compromising all machines would still not yield the full signature list, though it would allow for an attacker to test packets to see if they would be filtered. Filtered Traffic Third Party Signature Owner Garbler Third Party

6 Solutions Option #2: Distribute the Signature Information System should be capable of deep packet inspection. Performance must be practical. (If possible, make use of commodity FW technology.) Filtered Traffic Third Party Signature Owner Garbler Third Party

7 Project Goals To formally model our system and adversary and understand fundamental limits of what is possible. To seek new algorithms with provable correctness, performance, and security guarantees. (The ability to perform regular expression string matching in a secrecy preserving, and reasonably efficient manner, will likely require new crypto.) To use prototype-driven performance evaluation to validate the practicality of our most efficient solutions.

8 Project Schedule & Budget Phase 1 (formal model & fundamental limits): 4 months, $134,000 Phase 2 (algorithms & proofs): 5 months, $152,000 Phase 3 (system designs & prototypes): 6 months, $221,000 Total Budget: $507,000

9 Thank You