Certification and Authentication of Data Structures

We study query authentication schemes, algorithmic and cryptographic constructions that provideefficient and secure protocols for verifying the results of queries over structured data in untrusted oradversarial data distribution environments. We formally define the problem in a new data query and au-thentication setting that involves general query types answered in the RAM model of computation, andput forward a new approach for designing secure query authentication schemes that, through the newconcept of query certification, aims to authenticate the validity of the answer, rather than the entire pro-cess that generates the answer. Our main results state that this new authentication framework achievesgenerality, namely any query type admits a secure query authentication scheme, and also supports animportant type of modularity, namely the authentication of general queries based on the evaluation ofrelations over the data elements is reduced to the authentication of set-membership queries. Thus, in ad-dition to general possibility results under general assumptions and characterization results using existingcryptographic techniques, we contribute a clear separation between algorithmics and cryptography indata-authentication protocol design, and sufficient conditions for achieving super-efficient answer veri-fication in time asymptotically less than the time needed to answer the query.