Certificateless Ordered Sequential Aggregate Signature Scheme

Ordered sequential aggregate signature scheme is a signature scheme in which each signer for a group signs an individual document, and guarantees both of the validity of the document and the signing order. Many ordered sequential aggregate signature schemes are ID-based scheme and inherit an intrinsic insider problem, called key escrow problem, of the ID-based scheme. In this paper, we propose an ordered sequential aggregate signature scheme with certificate less property which solves the key escrow problem. Our proposed scheme can be regarded as a hybrid scheme of PKI and ID-based scheme and has the advantages of both of PKI and ID-based scheme. To the best of our knowledge, certificate less ordered sequential aggregate signature scheme has never been proposed. The proposed scheme is a pairing-based scheme and has a fixed signature size with respect to the number of signers. Also, the security of the proposed scheme is analyzed in the random oracle model.