Paper 2008/489

HAIL: A High-Availability and Integrity Layer for Cloud Storage

Kevin D. Bowers, Ari Juels, and Alina Oprea


We introduce HAIL (High-Availability and Integrity Layer), a distributed cryptographic system that permits a set of servers to prove to a client that a stored file is intact and retrievable. HAIL strengthens, formally unifies, and streamlines distinct approaches from the cryptographic and distributed-systems communities. Proofs in HAIL are efficiently computable by servers and highly compact---typically tens or hundreds of bytes, irrespective of file size. HAIL cryptographically verifies and reactively reallocates file shares. It is robust against an active, mobile adversary, i.e., one that may progressively corrupt the full set of servers. We propose a strong, formal adversarial model for HAIL, and rigorous analysis and parameter choices. We show how HAIL improves on the security and efficiency of existing tools, like Proofs of Retrievability (PORs) deployed on individual servers. We also report on a prototype implementation.

Available format(s)
Cryptographic protocols
Publication info
Published elsewhere. Unknown where it was published
storage securityproofs of retrievabilityerasure coding
Contact author(s)
aoprea @ rsa com
2009-04-20: last of 4 revisions
2008-11-21: received
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Creative Commons Attribution


      author = {Kevin D.  Bowers and Ari Juels and Alina Oprea},
      title = {HAIL: A High-Availability and Integrity Layer for Cloud Storage},
      howpublished = {Cryptology ePrint Archive, Paper 2008/489},
      year = {2008},
      note = {\url{}},
      url = {}
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