Cryptology ePrint Archive: Report 2020/1475

Delegate and Verify the Update Keys of Revocable Identity-Based Encryption

Kwangsu Lee

Abstract: Revocable identity-based encryption (RIBE) is an extension of identity-based encryption (IBE) and it supports efficient revocation of private keys. In the past, many efficient RIBE schemes have been proposed, but research on efficiently delegating the generation of update keys to a cloud server is somewhat insufficient. In this paper, we newly introduce the concept of delegated RIBE (DRIBE) that can delegate the generation of update keys to the cloud server and define the security models of DRIBE. Next, we propose a DRIBE scheme by generically combining a hierarchical IBE (HIBE) scheme, an identity-based broadcast encryption (IBBE) scheme, and a collision-resistant hash function. In addition, we propose a DRIBE-INC scheme that generates an occasional base update key and a periodic incremental update key to reduce the size of the update key in our DRIBE scheme.

Category / Keywords: public-key cryptography / Identity-based encryption, Key revocation, Update key delegation, Public Verifiability

Date: received 23 Nov 2020

Contact author: kwangsu at sejong ac kr

Available format(s): PDF | BibTeX Citation

Version: 20201124:113408 (All versions of this report)

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