Chapter

Transactions on Large-Scale Data- and Knowledge-Centered Systems IX

Volume 7980 of the series Lecture Notes in Computer Science pp 42-64

Recoverable Encryption through a Noised Secret over a Large Cloud

  • Sushil JajodiaAffiliated withGeorge Mason University
  • , Witold LitwinAffiliated withLAMSADE, Université Paris Dauphine
  • , Thomas Schwarz SJAffiliated withUniversidad Católica del Uruguay

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Abstract

The safety of keys is the Achilles’ heel of cryptography. A key backup at an escrow service lowers the risk of loosing the key, but increases the danger of key disclosure. We propose Recoverable Encryption (RE) schemes that alleviate the dilemma. RE encrypts a backup of the key in a manner that restricts practical recovery by an escrow service to one using a large cloud. For example, a cloud with ten thousand nodes could recover a key in at most 10 minutes with an average recovery time of five minutes. A recovery attempt at the escrow agency, using a small cluster, would require seventy days with an average of thirty five days. Large clouds have become available even to private persons, but their pay-for-use structure makes their use for illegal purposes too dangerous. We show the feaibility of two RE schemes and give conditions for their deployment.

Keywords

Cloud Computing Recoverable Encryption Key Escrow Privacy