Abstract:
The increasing model of e-commerce infrastructure opens the door for secure
transaction of information over Internet, keeping some records private as users'
choice within a few seconds. A user while frequently retrieves his records seldom
wish to hide the identity of the record to the database server. Private Information
Retrieval (PIR) protocols are such protocols that allow users to retrieve information
from a database while keeping their query private.
In many e-commerce applications, such as e-commerce, patent database,
pharmaceuticals database, media database, ethical hacking, bioinformatics and digital
library are vastly used fields of PIR protocol.
The performance of existing protocols depends on communication and computational
complexities. In some PIRs the computational complexity is reduced to 0(1), and
optimal, but still holds high communication complexity O(NJ. Where N; is the total
number of records in the database server.
This research introduces a new PIR protocol namely PIR with p-cache based on the
concept of database caching technology. A client is assigned a private account called
P-cache account protected by his private key, holding the recently accessed query
records. The P-cache is hash indexed and updated using the Least Recently Used
(LRU) algorithm. In average case, whenever a client requests a query in the system,
there is high probability to satisfy it from the p-cache instead to access in the main
database server that contains huge amounts of records. As the cache is hash indexed
the complexity is significantly reduced from O(Ns) tQ 0(1) in average.
The protocol has been evaluated by using randomly generated three schemas (Stdlnfo
joined with Books in Digital Library System, CustInfo joined with Products in PIR
based Electronic Payment System and Voterlnfo schema in the PIR based voting
system) and compared with the existing protocols. Experimental results show that the
proposed protocol is more realistic and faster then the previous protocols in terms on
computational and communication complexity.
