## Cryptology ePrint Archive: Report 2004/331

Code-Based Game-Playing Proofs and the Security of Triple Encryption

Mihir Bellare and Phillip Rogaway

Abstract: The game-playing technique is a powerful tool for analyzing cryptographic constructions. We illustrate this by using games as the central tool for proving security of three-key triple-encryption, a long-standing open problem. Our result, which is in the ideal-cipher model, demonstrates that for DES parameters (56-bit keys and 64-bit plaintexts) an adversary's maximal advantage is small until it asks about $2^{78}$ queries. Beyond this application, we develop the foundations for game playing, formalizing a general framework for game-playing proofs and discussing techniques used within such proofs. To further exercise the game-playing framework we show how to use games to get simple proofs for the PRP/PRF Switching Lemma, the security of the basic CBC~MAC, and the chosen-plaintext-attack security of OAEP.

Category / Keywords: Cryptographic analysis techniques,

Date: received 30 Nov 2004, last revised 28 Nov 2008

Contact author: mihir at cs ucsd edu

Available format(s): PDF | BibTeX Citation

Note: An earlier version of this paper was entitled "The Game-Playing Technique." The current version is substantially different.

Short URL: ia.cr/2004/331

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