Chris Lesniewski-Laas

A Sybil-proof one-hop DHT

Decentralized systems, such as structured overlays, are subject to the Sybil attack, in which an adversary creates many false identities to increase its influence. This paper describes a one-hop distributed hash table which uses the social links between users to strongly resist the Sybil attack. The social network is assumed to be fast mixing, meaning that a random walk in the honest part of the network quickly approaches the uniform distribution. As in the related SybilLimit system [25], with a social network of n honest nodes and m honest edges, the protocol can tolerate up to o(n/ log n) attack edges (social links from honest nodes to compromised nodes). The routing tables contain O(√m log m) entries per node and are constructed efficiently by a distributed protocol. This is the first sublinear solution to this problem. Preliminary simulation results are presented to demonstrate the approachs effectiveness.

SSL splitting: securely serving data from untrusted caches

A popular technique for reducing the bandwidth load on Web servers is to serve the content from proxies. Typically these hosts are trusted by the clients and server not to modify the data that they proxy. SSL splitting is a new technique for guaranteeing the integrity of data served from proxies without requiring changes to Web clients. Instead of relaying an insecure HTTP connection, an SSL splitting proxy simulates a normal Secure Sockets Layer (SSL) connection with the client by merging authentication records from the server with data records from a cache. This technique reduces the bandwidth load on the server, while allowing an unmodified Web browser to verify that the data served from proxies is endorsed by the originating server.SSL splitting is implemented as a patch to the industry-standard OpenSSL library, with which the server is linked. In experiments replaying two-hour access.log traces taken from LCS Web sites over an ADSL link, SSL splitting reduces bandwidth consumption of the server by between 25% and 90% depending on the warmth of the cache and the redundancy of the trace. Uncached requests forwarded through the proxy exhibit latencies within approximately 5% of those of an unmodified SSL server.

UIA: a user information architecture for personal devices

We are heading for a device information disaster. Many people already store information on dozens of devices, but are unable to organize and find their scattered information effectively. A given picture might be on a digital camera, a home PC, a laptop, an iPod Photo, or a cell phone. Even knowing a files location is often not enough, because the relevant device may be on the far side of a firewall or not currently plugged into a PCs USB port. Sharing pictures, documents, or multimedia with family, friends, and colleagues today requires one to upload the information from a portable device to a personal computer and then E-mail it, or copy files via a physical medium such as a USB key.