1. Architectural issues for network-layer identifiers Stefan Savage Dept of Computer Science & Engineering UC San Diego

2. Historical context I I n the beginning... it was amazing the net worked at all. Everyone was a good actor.

3. Existing Internet design Focused on universal connectivity IP address Identifiers purely for the purpose of connectivity Dst address for routing, Src to identify destination for replies Strictly voluntary Actively trying to introduce homogeneous substrate Unbound usage model Security not a significant consideration in the network layer; trust everyone equally Cryptography expensive relative to transport Cryptographic abstractions limited True when IPSec designed also

4. What has changed? Many users/providers dont want homogeneity Most src addresses today are NATed We want to limit who can talk to whom Huge growth in criminal activity 10s of millions of compromised machines Sophisticated abuse of network layer

5. Problems Network architecture provides how Security questions are mainly about who and what Ad hoc, brittle mappings between two Firewalls (address, port) Ingress/egress filtering DDoS filtering (ttl hack, blackholing, etc) Key issue Cant count on src address being correct or global Even if it is correct only represents existence of endpoint

6. Worth rethinking… How might we design packet identifiers to provide useful attribution? Attribution – working definition: The act of linking identity with action Uses Authentication: who wants to do that? Access control Situational awareness: who is doing that now? Operational response (e.g. filtering DDoS, BotNet C&C) Forensics: who did that in the past? Investigatory, evidentiary

7. Design options Meaning of identifier Network attribute IP address: topological endpoint Path: topological route (StackPI) Physical attribute Location: place packet sent from (used today in payment sys) Originator: machine packet sent from User attribute Capability: right to access something Principal: evidence of individual Scope of identifier (local, global, in-between) Who can interpret (anyone, trusted party, hybrid)

8. New opportunity Crypto has advanced significantly Many operations are comparatively cheap now 10s of microseconds Line-rate hardware implementations feasible Completely new kinds of cryptography Groups, aggregates, append-only, IBE, Attribute- based crypto, homomorphic crypto, broadcast systems, etc Its not just encrypt, hash and sign anymore… New tools provide new design opportunities

9. Remaining agenda Revisiting the Cryptographic toolbox (Boneh) Local identifiers for access control (Casado) Global identifiers for forensics (Savage)

10. Attribution To whom