DEPARTMENT SEMINAR

Randal Burns
Johns Hopkins University

Department of Computer Science

October 11, 2007
Computer Science Building, Room 151
4:00 PM

Faculty Host:Gerome Miklau

"Auditing Long-Term Archives Built on Untrusted Storage Systems"

Verifying the authenticity of data has emerged as a critical issue when storing data on untrusted servers. In general, such systems prevent storage servers from misrepresenting or modifying data by providing authenticity checks when accessing data. However, archival storage requires guarantees about the authenticity of data on storage, i.e. that a repository possesses and can reproduce the correct data. It is insufficient to detect that data have been modified or deleted when accessing the data, because it may be too late to recover lost or damaged data.

This talk presents provable data possession (PDP), which establishes that a server possesses data without returning the data to the client (verifier). PDP generates probabilistic proofs of possession by sampling random sets of blocks from the server, which drastically reduces I/O costs. It also uses a constant amount of metadata at the client to verify the proof and transmits a small, constant amount of data over the network. Thus, PDP supports large data sets in widely-distributed storage systems. The talk will also address practical issues in the implementation of PDP in archival stores, such as using PDP in conjunction with replication and erasure coding.