Delegation Chains Secure up to Constant Length

Masayuki ABE  Tatsuaki OKAMOTO  

IEICE TRANSACTIONS on Fundamentals of Electronics, Communications and Computer Sciences   Vol.E85-A   No.1   pp.110-116
Publication Date: 2002/01/01
Online ISSN: 
Print ISSN: 0916-8508
Type of Manuscript: Special Section PAPER (Special Section on Cryptography and Information Security)
proxy signature,  delegation chains,  ID-based signatures,  random oracles,  

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In this paper we discuss how one can delegate his power to authenticate or sign documents to others who, again, can delegate the power to someone else. A practical cryptographic solution would be to issue a certificate that consists of one's signature. The final verifier checks verifies the chain of these certificates. This paper provides an efficient and provably secure scheme that is suitable for such a delegation chain. We prove the security of our scheme against an adaptive chosen message attack in the random oracle model. Though our primary application would be agent systems where some agents work on behalf of a user, some other applications and variants will be discussed as well. One of the variants enjoys a threshold feature whereby one can delegate his power to a group so that they have less chance to abuse their power. Another application is an identity-based signature scheme that provides faster verification capability and less communication complexity compared to those provided by existing certificate-based public key infrastructure.