Cryptology ePrint Archive: Report 2002/064

Protecting against Key Exposure: Strongly Key-Insulated Encryption with Optimal Threshold

Mihir Bellare and Adriana Palacio

Abstract: A new framework for protection against key exposure was recently suggested by Dodis et. al.. We take its realization further towards practice by presenting simple new schemes that provide benefits over previous ones in terms of scalability, performance and security. Our first contribution is a simple, practical, scalable scheme called SKIE-OT that achieves the best possible security in their framework. SKIE-OT is based on the Boneh-Franklin identity-based encryption (IBE) scheme and exploits algebraic properties of the latter. We also show that the role of identity-based encryption is not coincidental by proving that IBE is equivalent to (not strongly) key-insulated encryption with optimal threshold and allowing random-access key updates.

Category / Keywords: public-key cryptography / Encryption, identity-based encryption, key-insulated encryption, key-exposure

Date: received 25 May 2002, last revised 26 Jun 2002

Contact author: mihir at cs ucsd edu

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Version: 20020627:034339 (All versions of this report)

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