Cryptology ePrint Archive: Report 2007/368

Reducing Trust in the PKG in Identity Based Cryptosystems

Vipul Goyal

Abstract: One day, you suddenly find that a private key corresponding to your Identity is up for sale at e-Bay. Since you do not suspect a key compromise, perhaps it must be the PKG who is acting dishonestly and trying to make money by selling your key. How do you find out for sure and even prove it in a court of law?

This paper introduces the concept of Accountable Authority Identity based Encryption (A-IBE). A-IBE is a new approach to mitigate the (inherent) key escrow problem in identity based encryption schemes. Our main goal is to restrict the ways in which the PKG can misbehave. In our system, if the PKG ever maliciously generates and distributes a decryption key for an Identity, it runs the risk of being caught and prosecuted.

In contrast to other mitigation approaches, our approach does not require multiple key generation authorities.

Category / Keywords: public-key cryptography / Identity based Encryption

Publication Info: Revised and extended version of a paper appearing at CRYPTO 2007

Date: received 13 Sep 2007, last revised 7 Dec 2007

Contact author: vipul at cs ucla edu

Available format(s): PDF | BibTeX Citation

Version: 20071207:093304 (All versions of this report)

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