1 Is an Internet PKI the Right Approach? Eric Osterweil Join work with: Dan Massey and Lixia Zhang

2 Life in the Internet The Internet is a uniquely challenging environment to deploy systems because: It is immense It is has a highly diverse makeup Its constituent components are constantly in flux and are administered by independent authorities As a result, systems must be designed to tolerate: Constant configuration errors, incremental deployments (which may take years), and diverse opinions on who is trustworthy

3 Problems The Internet’s heterogeneity makes it difficult for systems to rely on being fully deployed Systems must function while being incrementally deployed, broken, etc. Internet parties are notorious for not agreeing whom to trust Choosing “trusted authorities” often sparks debate Successful Internet Systems tend to be very tolerant of misconfigurations and multiple independent opinions Like DNS and BGP

4 DNS has tried Crypto The DNS Security Extensions (DNSSEC) RFCs Approach: a PKI following DNS’ hierarchy A single “island of security” rooted at DNS’ root zone Everyone trusts the root DNSSEC uses public key cryptography Each zone signs all of its own data, and the keys for its children zones too By bootstrapping with a single key (trust-anchor) from the root, all keys can be recursively learned

5 DNSSEC Status Today Only 10,459 secure zones have deployed Only about 900 seem to be production Root zone has not signed Rather than a single island there are % are singleton (isolated) zones This means 662 trust-anchors would be needed How can the keys for this many independent zones by globally verified? Operational management of cryptography has reduced its effectiveness Monitoring has shown that rapid re-signing leaves roughly 19.8% of data vulnerable to replays

6 A New Concept: Public-Space Trust doesn’t have to be predicated on the status of deployments Track public actions instead Public actions can be subjected to scrutiny Anyone may publish data Who has published data, its consistency, and its history can let each individual judge its veracity Misbehavior like Man-in-the-Middle (MITM) attacks cannot be denied when done in the Public-Space Global consistency can be evaluated by polling from multiple locations Local MITM attacks can be globally refuted in public

7 Public-Space Systems We record what is done rather than mandate what operators must do / who they must trust SecSpider DNSSEC key learning Because DNSSEC’s PKI has not evolved BGP-Origins BGP prefix attestation system Because BGP does not have a PKI

8 SecSpider Learns keys from many global pollers Keys are tracked over time Serves globally consistent keys Anyone can verify keys they have looked up Adversaries must compromise all pollers to subvert the Public-Space Results are not provably correct but practically effective Data owners check the Public-Space for correctness SecSpider is not a data authority We are formalizing this approach to achieve security through publicity

9 BGP-Origins BGP allows any Autonomous System (AS) to announce that it hosts any IP addresses (prefixes) ASes send out false announcements sometimes Pakistan hijacked YouTube by announcing its prefixes BGP-Origins uses global monitors (RouteViews) and tracks which ASes have announced which prefixes Also, any user can attest to a prefix-AS binding Operators could have attested to the proper binding of YouTube’s prefixes to avoid the hijack Users decide whom to trust and discard attestations from unknown parties

10 Ongoing Work Are conventional PKIs a good fit for the Internet? Operational groups disagree on many “trust” issues Public-Space applications are maturing Increasing usage is coming with ongoing publicity at operational meetings Public-Space can be a substitute for the missing PKI in DNSSEC’s partially deployed state Users can verify data against what is in the Public-Space With no PKI for BGP, the Public-Space uses real- world trust that already exists between operators Addresses attacks and misconfigurations

11 Thank You Questions?