A Study On Linearly Homomorphic Signatures With Designated Entities

Linearly homomorphic signatures allow any entity,without the knowledge of the signer's private key,to linearly combine the signed messages and derive a valid signature on the combined-message.It aims at providing authenticity,integrity and non-repudiation of the signed messages in areas such,as network coding,proofs of storage and verifiable computa.tion mechanisms.At present,linearly homomorphic signatures usually enjoy public combinability and public verifiability.However,in applications such as verifiable computation mechanisms,the signer hopes that only the cloud server can obtain the power of combining signatures,and other entities only have the ability to verify signatures.Based on this,two kinds of linearly homomorphic signatures with special properties are proposed,and the main contents of this paper include the following two aspects:1.Motivated by Professor Ronald L.Rivest,a Turing Prize winner,this paper introduces the concept of the designated combiner into linearly homomorphic signatures,and proposes linearly homomorphic signatures with designated com-biner(LHSDC).In LHSDC,the power of combining the authenticated data is given to only one entity.As a result,the signer need not use a secure channel to send the signatures,and other entities cannot recombine the signatures gen-erated by the combiner.In our scheme,the signer can distribute multiple files and designate multiple entities as the combiners without updating the public key.2.Another work of this paper is to introduce the concept of the designated verifier into LHSDC,and propose linearly homomorphic signatures with designated en-tities(LHSDE).In LHSDE,only one entity can be convinced by the validity of the signatures.On one hand,the privacy of the signer is well protected;on the other hand,the verifier is prevented from propagating the signatures generated by the combiner.In our scheme,the combiner can designated multiple entities as verifiers without updating the public key.