deduplication-side-channel · research · also duplicate-presence oracle

Deduplication side channel

A deduplication side channel leaks information about stored content through observable behavior caused by duplicate detection.

Related Observatory article: Deduplication side channel on hesela.com

In the source-side, cross-user setting studied by Harnik and colleagues, upload suppression can reveal prior content presence without identifying its owner. Server-side matching after a complete upload removes that particular signal, not every possible side channel. Their observations concern historical service versions, not present-day provider behavior. [1]

Relations

related
deduplication, convergent-encryption, content-defined-chunking

Citations

  1. Harnik, Pinkas and Shulman-Peleg. Side channels in cloud services, the case of deduplication in cloud storage (2010), sections 2-3. (accessed 2026-10-18)

Further reading

  1. Hesela: Encrypted deduplication: who can test a file guess? (accessed 2026-10-18)

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Hesela team. Deduplication side channel. Hesela. 2026-10-18. https://hesela.dev/terms/deduplication-side-channel/