Carlisle M. Adams
Pair-wise Cryptographic Models for Secure Data Exchange in P2P Database Management Systems
A peer-to-peer database management system(P2PDBMS) is a collection of autonomous data sources, called peers. In this system each peer augments a conventional database management system with an inter-operability layer (i.e. mappings/policies) for sharing data and services. Peers exchange data in a pair-wise fashion on-the-fly in response to a query without any centralized control. Generally, the communication link between two peers is insecure and peers create a temporary session while exchanging data. When peers exchange highly confidential data between them over an insecure communication network, such as the Internet, the data might be trapped and disclosed by the intruders. In a P2PDBMS there is no centralized control for data exchange, hence we cannot assume any central third party security infrastructure (e.g. PKI) to protect confidential data. So far, there is currently no available/existing security protocol for secured data exchange in P2PDBMS. In this paper we propose three models for secure data exchange in P2PDBMSs and the corresponding security protocols. The proposed protocol allows the peers to compute their secret session keys dynamically during data exchange based on the policies between them. Our proposed protocol is robust against the man-in-the middle attack, the masquerade attack, and the reply attack.
Designing Against the `Overdefined System of Equations' Attack
Recently, Courtois and Pieprzyk proposed an attack on symmetric ciphers that takes advantage of a previously-unexploited property of substitution boxes, or s-boxes, in the round function. This paper gives a brief overview of this ``overdefined system of equations'' attack and shows how the attack may be avoided through the use of round functions that contain a variety of protection mechanisms, including combinations of operators from different algebraic groups, a circular rotation step, and substitution boxes (s-boxes) of large dimension.