Cryptology ePrint Archive: Report 2019/1135

A Provably Secure Conditional Proxy Re-Encryption Scheme without Pairing

Arinjita Paul and S. Sharmila Deva Selvi and C. Pandu Rangan

Abstract: Blaze, Bleumer and Strauss introduced the notion of proxy re-encryption (PRE), which enables a semi-trusted proxy to transform ciphertexts under Alice's public key into ciphertexts under Bob's public key. The important property to note here is, the proxy should not learn anything about the plaintext encrypted. In 2009, Weng et al. introduced the concept of conditional proxy re-encryption (CPRE), which permits the proxy to re-encrypt only ciphertexts satisfying a condition specified by Alice into a ciphertext for Bob. CPRE enables fine-grained delegation of decryption rights useful in many practical scenarios, such as blockchain-enabled distributed cloud storage and encrypted email forwarding. Several CPRE schemes exist in the literature based on costly bilinear pairing operation in the random oracle model. We propose the first construction of an efficient CPRE scheme without pairing, satisfying chosen ciphertext security under the computational Diffie Hellman (CDH) assumption and its variant in the random oracle model.

Category / Keywords: public-key cryptography / Proxy Re-Encryption, Public Key, Conditional, Pairing-less, Unidirectional, Single hop, CCA-secure

Date: received 2 Oct 2019, last revised 2 Oct 2019

Contact author: arinjita paul at gmail com

Available format(s): PDF | BibTeX Citation

Version: 20191003:064300 (All versions of this report)

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