Design And Implementation Of P2P Database Content Authentication Scheme

In recent years, the technology of resource sharing based on P2P network has been developed quickly, P2P database is an important research direction in this field. Content authentication judging whether database content has been juggled, is one key constructing step of P2P database. Database content authentication insures that the homonymy databases on system have the same relation structure and stored data. So parallel query can be provided, and the query speed of P2P database can be improved much.Because database is a structured data set and the data sharing granularity is smaller, content authentication has much difficulty. Character distilling and data watermark, which have successful application on image and text content authentication, have obvious deficiency on database content authentication when using one of them only.Based on above consideration, using the technology advantage of character distilling and data watermark, regard data watermark as one level character vector, a new P2P database content authentication scheme is designed.The notion of four level character vectors is introduced. The former three character vectors reflects the structure character of database and the whole data character of key attributes, the fourth level character vector is the data watermark embedded into database when the database appears in system for the first time. The fourth level character vector using sensitivity of brittle data watermark sufficiently, which judges whether the database has been juggled through watermark distilling and comparing, is a good complement to the former three character vectors.The scheme of database content authentication and algorithms of watermark embedding and distilling are proposed. When a database appears in system for the first time, its distilled character vector is saved into character database in center server. When database content should be authenticated, character vector will be distilled again.The prototype system is developed on .NET platform with SQL Server2000 database, in which the key implement technology and design of character database are introduced.