SEMINAR ANNOUNCEMENT
             CENTER FOR SECURE INFORMATION SYSTEMS
                    GEORGE MASON UNIVERSITY
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             Date :  Thursday, April 19, 2012
             Time :  11:00 - 12:00
         Location :  Research Hall, Room 401
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Recoverable Encryption through Noised Secret over Large Cloud 

Professor Witold Litwin
Université Paris Dauphine, Lamsade

Encryption key safety is the Achilles' heel of modern cryptography. Simple backup copies offset the risk of key loss, but increase the danger of disclosure, including at the escrow's site. Recoverable Encryption (RE) alleviates the dilemma. The backup is specifically encrypted so that recovery by brute force, i.e., without any hint from the key owner remains intentionally cumbersome but feasible. We propose RE using so-called noised secret. To dissuade indelicate attempts, the owner sets up the decryption complexity so that recovery at the escrow's facility, a computer or perhaps a cluster, becomes inhibitive. The actual recovery fits the time desired by the requestor, provided the use of a large cloud. A 10K-node cloud may suffice to recover the key in ten minutes, for the dissuasive set up of seventy days at an escrow's a computer.  Large public clouds are now available with acceptable price tags. An illegal use of such a huge resource is unlikely.  We show feasibility of our schemes and their practical potential.

**Point of contact:  Prof Sushil Jajodia jajodia@gmu.edu
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