# Secure and Private Cloud Storage Systems with Random Linear Fountain Codes

## TL;DR

This paper introduces SAPIR, an information-theoretic framework for secure and private data retrieval in distributed cloud storage using Random Linear Fountain codes, ensuring secrecy and privacy even with server collusion.

## Contribution

It presents a novel coding scheme combining RLF codes with a PIR protocol that guarantees asymptotic perfect secrecy and privacy against colluding servers.

## Key findings

- Achieves asymptotic perfect secrecy with at least one uncorrupted server.
- Provides a PIR scheme that protects user privacy against multiple colluding servers.
- Demonstrates the effectiveness of the approach in distributed storage systems.

## Abstract

An information theoretic approach to security and privacy called Secure And Private Information Retrieval (SAPIR) is introduced. SAPIR is applied to distributed data storage systems. In this approach, random combinations of all contents are stored across the network. Our coding approach is based on Random Linear Fountain (RLF) codes. To retrieve a content, a group of servers collaborate with each other to form a Reconstruction Group (RG). SAPIR achieves asymptotic perfect secrecy if at least one of the servers within an RG is not compromised. Further, a Private Information Retrieval (PIR) scheme based on random queries is proposed. The PIR approach ensures the users privately download their desired contents without the servers knowing about the requested contents indices. The proposed scheme is adaptive and can provide privacy against a significant number of colluding servers.