Cloud Data Placing and private information retrieval algorithms

The authors consider the problem of ensuring secure queries to the database PIR (Private Information Retrieval) problem. Previously, the authors considered the problem for a database hosted in the cloud in the presence of an active adversary who does not interfere with the execution of the protocol, but can carry out an attack with known open queries. In algorithms, bit number i is represented as the l-ary number with a number of digits d. An algorithm for placing a database in the cloud and an algorithm for querying the required bit using permutations in the digits of the bit number, using the specification of the bit number i in the base l numerical system, were proposed. Permutations are treated as secret encryption keys. Communication complexity and probability of guessing the bit number for a one-time attack with a known open request for bit number i and for an attack with unlimited number of known open requests were estimated.