Certificateless universal designated multi-verifiers sequential multi-signature scheme
Sequential multi-signature schemes were based on discrete logarithm problem or identity,and existed certificate management and key escrow problems.Universal designated multi-verifiers signature scheme allowed a signature holder to designate a set of signature verifiers,in such a way that only designated verifiers could verify the efficiency of the signature.Combining certificateless signature with universal designated multi-verifiers signature,certificateless universal designated multi-verifiers sequential multi-signature scheme and its safety requirement were proposed.Security proofs based on the random oracle model indicate that this scheme can resist the adaptively select of message attack,and its security relies on the BDH assumption.
We continue the study of bottom-up unranked tree automata with equality and ::: disequality constraints between direct subtrees. In particular, we show that ::: the emptiness problem for the nondeterministic automata is decidable. In ::: addition, we show that the universality problem, in contrast, is undecidable.