Fault tolerant and secure data retrieval from wireless sensor networks

An erasure encoding based on arithmetic residue codes with non-pairwise-prime moduli is introduced. Data are encoded with n residue digits, and can be reconstructed exactly from any subset of at least n-z available digits not bearing errors. Data can also be reconstructed within a small ? from at least n-z available digits bearing small errors, or from at least n-z-2 available digits bearing a single unrestricted error combined with small errors. Integers z and ? are depending on the actual moduli and redundancy, and small errors are those of magnitude not exceeding ?. Encoding and decoding of data requires simple arithmetic computation. The proposed encoding is suitable for application to wireless sensor networks, when data robustness and confidentiality are critical issues. To this purpose, data are independently collected by n replicated sensing nodes, each replica storing a different digit of the encoded data. This produces data dispersal without requiring wireless communication between nodes. Data retrieval tolerates failure of multiple sensor, as well as small errors arising from independent data collection, and unrestricted errors due to failures or intrusions. The proposed encoding reduces memory and energy requirements of nodes, and contributes to strengthened data security and confidentiality.