Cryptology ePrint Archive: Report 2004/338

Identity-Based Hierarchical Strongly Key-Insulated Encryption and Its Application

Yumiko Hanaoka and Goichiro Hanaoka and Junji Shikata and Hideki Imai

Abstract: In this paper, we discuss non-interactive updating of decryption keys in identity-based encryption (IBE). IBE is a public key cryptosystem where a public key is an arbitrary string. In practice, key revocation is a necessary and inevitable process and IBE is no exception when it comes to having to manage revocation of decryption keys without losing its merits in efficiency. Our main contribution of this paper is to propose novel constructions of IBE where the decryption key can be renewed without having to make changes to its public key, i.e. user's identity. We achieve this by tactfully extending the hierarchical IBE (HIBE). Regarding security, we address semantic security against adaptive chosen cipher-text attack for a very strong attack environment that models all possible types of key exposures in the random oracle model. Straightforward extension of the HIBE, however, does not achieve our goal and such scheme is completely insecure under our attack model. In addition to this, we show method of constructing (partially collusion resistant) HIBE from arbitrary IBE in the random oracle model. By combining these results, we can construct an IBE with non-interactive key update from only an arbitrary IBE.

Category / Keywords: public-key cryptography /

Date: received 2 Dec 2004, last revised 12 Dec 2005

Contact author: hanaoka-goichiro at aist go jp

Available format(s): Postscript (PS) | Compressed Postscript (PS.GZ) | PDF | BibTeX Citation

Note: This paper supersedes a previous version which is entitled as "Identity-Based Encryption with Non-Interactive Key Update".

Version: 20051212:081237 (All versions of this report)

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