Cryptology ePrint Archive: Report 2010/369

Double Ciphertext Mode : A Proposal for Secure Backup

Debrup Chakraborty and Cuauhtemoc Mancillas-Lopez

Abstract: Security of data stored in bulk storage devices like the hard disk has gained a lot of importance in the current days. Among the variety of paradigms which are available for disk encryption, low level disk encryption is well accepted because of the high security guarantees it provides. In this paper we view the problem of disk encryption from a different direction. We explore the possibility of how one can maintain secure backups of the data, such that loss of a physical device will mean neither loss of the data nor the fact that the data gets revealed to the adversary. We propose an efficient solution to this problem through a new cryptographic scheme which we call as the double ciphertext mode (DCM). In this paper we describe the syntax of DCM, define security for it and give some efficient constructions. Moreover we argue regarding the suitability of DCM for the secure backup application and also explore other application areas where a DCM can be useful.

Category / Keywords: secret-key cryptography /

Date: received 25 Jun 2010

Contact author: debrup at cs cinvestav mx

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Version: 20100628:181754 (All versions of this report)

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