158 research outputs found
Security Analysis of the Unrestricted Identity-Based Aggregate Signature Scheme
Aggregate signatures allow anyone to combine different signatures signed by
different signers on different messages into a single short signature. An ideal
aggregate signature scheme is an identity-based aggregate signature (IBAS)
scheme that supports full aggregation since it can reduce the total transmitted
data by using an identity string as a public key and anyone can freely
aggregate different signatures. Constructing a secure IBAS scheme that supports
full aggregation in bilinear maps is an important open problem. Recently, Yuan
{\it et al.} proposed an IBAS scheme with full aggregation in bilinear maps and
claimed its security in the random oracle model under the computational
Diffie-Hellman assumption. In this paper, we show that there exists an
efficient forgery attacker on their IBAS scheme and their security proof has a
serious flaw.Comment: 9 page
Practical Certificateless Aggregate Signatures From Bilinear Maps
Aggregate signature is a digital signature with a striking property that anyone can aggregate n individual signatures on n different messages which are signed by n distinct signers, into a single compact signature to reduce computational and storage costs. In this work, two practical certificateless aggregate signature schemes are proposed from bilinear maps. The first scheme CAS-1 reduces the costs of communication and signer-side computation but trades off the storage, while CAS-2 minimizes the storage but sacrifices the communication costs. One can choose either of the schemes by consideration of the application requirement. Compare with ID-based schemes, our schemes do not entail public key certificates as well and achieve the trust level 3, which imply the frauds of the authority are detectable. Both of the schemes are proven secure in the random oracle model by assuming the intractability of the computational Diffie-Hellman problem over the groups with bilinear maps, where the forking lemma technique is avoided
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