Abstract. The paper extends the idea of negative representations of information for enhancing privacy. Simply put, a set DB of data elements can be represented in terms of its complement set. That is, all the elements not in DB are depicted and DB itself is not explicitly stored. We review the negative database (NDB) representation scheme for storing a negative image compactly and propose a design for depicting a multiple record DB using a collection of NDBs—in contrast to the single NDB approach of previous work. Finally, we present a method for creating negative databases that are hard to reverse in practice, i.e., from which it is hard to obtain DB, by adapting a technique for generating 3-SAT formulas. 1

The Netlib repository, maintained by the University of Tennessee and Oak Ridge National Laboratory, contains freely available software, documents, and databases of interest to the numerical, scientific computing, and other communities. This report includes both the Netlib User's Guide and the Netlib System Manager's Guide, and contains information about Netlib's databases, interfaces, and system implementation. The Netlib repository's databases include the Performance Database, the Conferences Database, and the NA-NET mail forwarding and Whitepages databases. A variety of user interfaces enable users to access the Netlib repository in the manner most convenient and compatible with their networking capabilities. These interfaces include the Netlib email interface, the Xnetlib X Windows client, the netlibget command-line TCP/IP client, anonymous ftp, anonymous rcp, and gopher. Work on Netlib is supported by National Science Foundation under Grant. No. ASC9103853. Work on Xnetlib is sup...

The paper introduces the concept of a negative database, in which a set of records DB is represented by its complement set. That is, all the records not in DB are represented, and DB itself is not explicitly stored. After introducing the concept, several results are given regarding the feasibility of such a scheme and its potential for enhancing privacy. It is shown that a database consisting of n, l-bit records can be represented negatively using only O(ln) records. It is also shown that membership queries for DB can be processed against the negative representation in time no worse than linear in its size and that reconstructing the database DB represented by a negative database NDB given as input is an NP-hard problem when time complexity is measured as a function of the size of NDB.

This paper introduces and describes new protocols for proving knowledge of secrets without giving them away: if the verifier does not know the secret, he does not learn it. Three role configurations exist for this type of protocols: (1) the prover may want to pro-actively prove knowledge of a secret, (2) a verifier may ask someone to prove knowledge of a secret, or (3) two players may mutually prove knowledge of a secret. Protocols for all three cases are shown in this paper. This can all be done while only using one-way hash functions. If also the use of encryption is allowed, these goals can be reached in a more efficient way, giving a total of six protocols (three without encryption and three with).