Compact Signature Aggregation from Module-Lattices

An aggregate signature scheme allows multiple signatures generated by different people for different messages to be aggregated into a compact aggregate signature. We propose the first signature aggregation scheme that (1) grows the size of the aggregate signature only logarithmically in the number of signatures to be aggregated, (2) is many-time, (3) supports non-interactive aggregation, (4) its security is based on the standard lattice assumption in the random oracle model. To obtain the result, we construct a new compact non-interactive batch argument (BARG) for NP. Our BARG has a very compact proof and its security is based on the standard module lattice assumptions in the random oracle model

Tight reduction for generic construction of certificateless signature and its instantiation from DDH assumption

Certificateless signature was proposed by Al-Riyami and Paterson to eliminate the certificate management in the public-key infrastructures and solve the key escrow problem in the identity-based signature. In 2007, Hu et al. proposed a generic construction of certificateless signature. They construct certificateless signature scheme from any standard identity-based signature and signature scheme.However, their security reduction is loose; the security of the constructed scheme depends on the number of users. In this paper, we give the tight reduction for their construction and instantiate a tightly-secure certificateless signature scheme without pairing from DDH assumption. Best of our knowledge, this scheme is the first tightly-secure certificateless signature scheme