  A Private Information Retrieval (PIR) protocol based on coding theory for a
single server is proposed. It provides computational security against linear
algebra attacks, addressing the main drawback of previous PIR proposals based
on coding theory. The approach involves two types of codes each one over a
different ring, an inner non-free linear code that will be used as a
distinguisher of some elements added to the query matrix, and an outer code
that will be used for generating the query matrix. Moreover, it only uses
modular arithmetic at the server level and the recovering stage if the base
ring chosen for the inner code is $\mathbb Z_m$.
