Cryptology ePrint Archive: Report 2019/418

Sharing of Encrypted files in Blockchain Made Simpler

S. Sharmila Deva Selvi and Arinjita Paul and Siva Dirisala and Saswata Basu and C. Pandu Rangan

Abstract: Recently, blockchain technology has attracted much attention of the research community in several domains requiring transparency of data accountability, due to the removal of intermediate trust assumptions from third parties. One such application is enabling file sharing in blockchain enabled distributed cloud storage. Proxy re-encryption is a cryptographic primitive that allows such file sharing by re-encrypting ciphertexts towards legitimate users via semi-trusted proxies, without them learning any information about the underlying message. To facilitate secure data sharing in the distributed cloud, it is essential to construct efficient proxy re-encryption protocols. In this paper, we introduce the notion of proxy self re-encryption (SE-PRE) that is highly efficient, as compared to the existing PRE schemes in the literature. We show that our self encryption scheme is provably CCA secure based on the DLP assumption and our proxy re-encryption scheme with self encryption is CCA secure under the hardness of the Computational Diffie Hellman (CDH) and Discrete Logarithm (DLP) assumption. Our novel encryption scheme, called self encryption, has no exponentiation or costly pairing operation. Even the re-encryption in SE-PRE does not have such operations and this facilitates the service provider with efficiency gain.

Category / Keywords: public-key cryptography / blockchain, proxy re-encryption, self-encryption, CCA, cloud storage

Original Publication (with major differences): The 1st International Conference on Mathematical Research for Blockchain Economy (Marble 2019)

Date: received 22 Apr 2019

Contact author: arinjita paul at gmail com, sharmioshin@gmail com, prangan55@gmail com

Available format(s): PDF | BibTeX Citation

Version: 20190424:132834 (All versions of this report)

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