UNI-MB - logo
UMNIK - logo
 
E-resources
Peer reviewed Open access
  • Private Information Retriev...
    Tajeddine, Razane; Gnilke, Oliver W.; El Rouayheb, Salim

    IEEE transactions on information theory, 11/2018, Volume: 64, Issue: 11
    Journal Article

    The problem of providing privacy, in the private information retrieval (PIR) sense, to users requesting data from a distributed storage system (DSS), is considered. The DSS is coded by an <inline-formula> <tex-math notation="LaTeX">(n,k,d) </tex-math></inline-formula> maximum distance separable code to store the data reliably on unreliable storage nodes. Some of these nodes can be spies which report to a third party, such as an oppressive regime, which data is being requested by the user. An information theoretic PIR scheme ensures that a user can satisfy its request while revealing no information on which data is being requested to the nodes. A user can trivially achieve PIR by downloading all the data in the DSS. However, this is not a feasible solution due to its high communication cost. We construct PIR schemes with low download communication cost. When there is <inline-formula> <tex-math notation="LaTeX">b=1 </tex-math></inline-formula> spy node in the DSS, in other words, no collusion between the nodes, we construct PIR schemes with download cost <inline-formula> <tex-math notation="LaTeX">\frac {1}{1-R} </tex-math></inline-formula> per unit of requested data (<inline-formula> <tex-math notation="LaTeX">R=k/n </tex-math></inline-formula> is the code rate), achieving the information theoretic limit for linear schemes. The proposed schemes are universal since they depend on the code rate, but not on the generator matrix of the code. Also, if <inline-formula> <tex-math notation="LaTeX">b\leq n-\delta k </tex-math></inline-formula> nodes collude, with <inline-formula> <tex-math notation="LaTeX">\delta =\lfloor {\frac {n-b}{k}}\rfloor </tex-math></inline-formula>, we construct linear PIR schemes with download cost <inline-formula> <tex-math notation="LaTeX">\frac {b+\delta k}{\delta } </tex-math></inline-formula>.