Cryptology ePrint Archive: Report 2018/834

Identity-based Encryption Tightly Secure under Chosen-ciphertext Attacks

Dennis Hofheinz and Dingding Jia and Jiaxin Pan

Abstract: We propose the first identity-based encryption (IBE) scheme that is (almost) tightly secure against chosen-ciphertext attacks. Our scheme is efficient, in the sense that its ciphertext overhead is only seven group elements, three group elements more than that of the state-of-the-art passively (almost) tightly secure IBE scheme. Our scheme is secure in a multi-challenge setting, i.e., in face of an arbitrary number of challenge ciphertexts. The security of our scheme is based upon the standard symmetric external Diffie-Hellman assumption in pairing-friendly groups, but we also consider (less efficient) generalizations under weaker assumptions.

Category / Keywords: identity-based encryption, chosen-ciphertext security, tight security reductions

Original Publication (in the same form): IACR-ASIACRYPT-2018

Date: received 5 Sep 2018, last revised 29 Nov 2018

Contact author: dennis hofheinz at kit edu, jiadingding@iie ac cn, jiaxin pan@kit edu

Available format(s): PDF | BibTeX Citation

Note: add the omitted proofs in appendix, we aslo give two instatiations of the construction

Version: 20181130:014735 (All versions of this report)

Short URL: ia.cr/2018/834


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