Cryptology ePrint Archive: Report 2004/258
Escrow-Free Encryption Supporting Cryptographic Workflow
S.S. Al-Riyami and J. Malone-Lee and N.P. Smart
Abstract: Since Boneh and Franklin published their seminal paper on identity
based encryption (IBE) using the Weil pairing , there has been a great
deal of interest in cryptographic primitives based on elliptic-curve pairings.
One particularly interesting application has been to control access to
data, via possibly complex policies.
In this paper we continue the research in this vein. We present an
encryption scheme such that the receiver of an encrypted message can
only decrypt if it satisfies a particular policy chosen by
the sender at the time of encryption.
Unlike standard IBE, our encryption scheme is escrow free in that no
key-issuing authority (or colluding set of key-issuing authorities) is
able to decrypt ciphertexts itself.
In addition we describe a security model for the scenario in question
and provide proofs of security for our scheme (in the random oracle model).
Category / Keywords: cryptographic protocols / pairings
Date: received 7 Oct 2004, last revised 5 May 2005
Contact author: nigel at cs bris ac uk
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Version: 20050505:081520 (All versions of this report)
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