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Erschienen in:
2007 | OriginalPaper | Buchkapitel
Rerandomizable RCCA Encryption
verfasst von : Manoj Prabhakaran, Mike Rosulek
Erschienen in: Advances in Cryptology - CRYPTO 2007
Verlag: Springer Berlin Heidelberg
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We give the first perfectly rerandomizable, Replayable-CCA (RCCA) secure encryption scheme, positively answering an open problem of Canetti et al. (
CRYPTO
2003). Our encryption scheme, which we call the
Double-strand Cramer-Shoup scheme
, is a non-trivial extension of the popular Cramer-Shoup encryption. Its security is based on the standard DDH assumption. To justify our definitions, we define a powerful “Replayable Message Posting” functionality in the Universally Composable (UC) framework, and show that any encryption scheme that satisfies our definitions of rerandomizability and RCCA security is a UC-secure implementation of this functionality. Finally, we enhance the notion of rerandomizable RCCA security by adding a receiver-anonymity (or key-privacy) requirement, and show that it results in a correspondingly enhanced UC functionality. We leave open the problem of constructing a scheme achieving this enhancement.