DMCA
Fully Secure Self-Updatable Encryption in Prime Order Bilinear Groups∗
BibTeX
@MISC{Datta_fullysecure,
author = {Pratish Datta and Ratna Dutta and Sourav Mukhopadhyay},
title = {Fully Secure Self-Updatable Encryption in Prime Order Bilinear Groups∗},
year = {}
}
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Abstract
Abstract. In CRYPTO 2012, Sahai et al. raised the concern that in a cloud control system revo-cation of past keys should also be accompanied by updation of previously generated ciphertexts in order to prevent unread ciphertexts from being read by revoked users. Self-updatable encryption (SUE), introduced by Lee et al. in ASIACRYPT 2013, is a newly developed cryptographic primitive that realizes ciphertext update as an inbuilt functionality and thus improves the efficiency of key revocation and time evolution in cloud management. In SUE, a user can decrypt a ciphertext asso-ciated with a specific time if and only if the user possesses a private key corresponding to either the same time as that of the ciphertext or some future time. Furthermore, a ciphertext attached to a certain time can be updated to a new one attached to a future time using only public information. The SUE schemes available in the literature are either (a) fully secure but developed in a composite order bilinear group setting under highly non-standard assumptions or (b) designed in prime order bilinear groups but only selectively secure. This paper presents the first fully secure SUE scheme in prime order bilinear groups under standard assumptions, namely, the Decisional Linear and the Decisional Bilinear Diffie-Hellman assumptions. As pointed out by Freeman (EUROCRYPT 2010) and Lewko (EUROCRYPT 2012), the communication and storage, as well as, computational effi-ciency of prime order bilinear groups are much higher compared to that of composite order bilinear groups with an equivalent level of security. Consequently, our SUE scheme is highly cost-effective than the existing fully secure SUE.
Keyphrases
prime order bilinear group secure self-updatable encryption future time composite order bilinear group unread ciphertexts cryptographic primitive cloud control system revo-cation certain time inbuilt functionality computational effi-ciency prime order sue scheme self-updatable encryption decisional linear public information key revocation past key standard assumption cloud management decisional bilinear diffie-hellman assumption equivalent level specific time secure sue scheme revoked user non-standard assumption secure sue ciphertext update private key time evolution
