Convergent Dispersal: Toward Storage-Efficient Security in a Cloud-of-Clouds.

Cloud-of-clouds storage exploits diversity of cloud storage vendors to provide fault tolerance and avoid vendor lock-ins. Its inherent diversity property also enables us to offer keyless data security via dispersal algorithms. However, the keyless security of existing dispersal algorithms relies on the embedded random information, which breaks data deduplication of the dispersed data. To simultaneously enable keyless security and deduplication, we propose a novel dispersal approach called convergent dispersal, which replaces original random information with deterministic cryptographic hash information that is derived from the original data but cannot be inferred by attackers without knowing the whole data. We develop two convergent dispersal algorithms, namely CRSSS and CAONT-RS. Our evaluation shows that CRSSS and CAONT-RS provide complementary performance advantages for different parameter settings.