Cryptology ePrint Archive: Report 2003/096

Secure Proxy Signature Schemes for Delegation of Signing Rights

Alexandra Boldyreva and Adriana Palacio and Bogdan Warinschi

Abstract: A proxy signature scheme permits an entity to delegate its signing rights to another entity. These schemes have been suggested for use in numerous applications, particularly in distributed computing. But to date, no proxy signature schemes with guaranteed security have been proposed; no precise definitions or proofs of security have been provided for such schemes. In this paper, we formalize a notion of security for proxy signature schemes and present provably-secure schemes. We analyze the security of the well-known delegation-by-certificate scheme and show that after some slight but important modifications, the resulting scheme is secure, assuming the underlying standard signature scheme is secure. We then show that employment of the recently introduced aggregate signature schemes permits bandwidth and computational savings. Finally, we analyze the proxy signature scheme of Kim, Park and Won, which offers important performance benefits. We propose modifications to this scheme that preserve its efficiency, and yield a proxy signature scheme that is provably secure in the random-oracle model, under the discrete-logarithm assumption.

Category / Keywords: cryptographic protocols / Applied cryptography, digital signature schemes, proxy signature schemes, aggregate signature

Date: received 20 May 2003, last revised 3 Feb 2008

Contact author: sasha at gatech edu

Available format(s): PDF | BibTeX Citation

Note: A few recent references are added.

Version: 20080203:233933 (All versions of this report)

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