Research On Delegation Based Digital Signature

With the rapid development of computer network and information technology, digitalsignature technology is widely used. Many domestic and foreign experts and scholars carriedout deep research on the theory, technology and applications of digital signature. Accordingto the needs of application background actually, a lot of special digital signature primitiveshave been proposed, among them, proxy signature and designated verifier signature are im-portant two kinds. These two kind of signatures have some kind of authorized function.The proxy signature generally studies the problem of authorization in digital signature. Inthe designated verifier signature scheme, the signer can designate the signature to any de-sired designated verifier, such that only the designated verifier can verify the validity of thissignature. In order to adapt the application environment, many extended proxy signatureand designated verifier signature primitives have been proposed. In this thesis, we do someresearch on proxy signature, proxy multi-signature, multi-proxy signature and universal des-ignated verifier signature. Our main achievements are as follows:1. We do research on identity based proxy signature scheme. In 2005, Gu and Zhu [36]showed how to construct an identity-based proxy signature scheme from any secureidentity-based signature scheme. However, the scheme constructed from any secureidentity-based signature scheme need PKG to extract the secret proxy signing keys. Inpractice, the proxy signer may want to generate the secret proxy signing key by him-self. Thus, we give the first direct construction of an identity based proxy signaturescheme that is provably secure in the standard model. Our scheme is based on an iden-tity based signature scheme in [74], and we prove our identity based proxy signaturescheme to be secure under the computational Diffie-Hellman assumption.2. We do research on proxy multi-signature.Proxy multi-signature is an important extended application of proxy signature. Al-though some research work has been done and many schemes have been presented, tillnow, all of the previous schemes weren't been proved secure formally.Cryptanalysis of an existing proxy multi-signature scheme is presented. Main aws and insecurity of this signature are pointed out. We formalize a notion of security for proxy multi-signature scheme. Based onthe BLS short signature scheme, we put forward a new proxy multi-signaturescheme. Unlike the previously proposed schemes, our new schemes have beenproved secure formally assuming the hardness of computable Diffie-Hellmanproblem under random oracle model.Based on the Waters'signature scheme, we put forward a new proxy multi-signature scheme and provide provable security proof in the standard model.Weproposeanewidentitybasedproxymulti-signatureschemeandprovideprov-able security proof under random oracle model for it.3. We do research on multi-proxy signature.Based on the Waters'signature scheme, we give the first construction of a multi-proxy signature scheme that is provably secure in the standard model.We do research on identity based multi-proxy signature, we propose the securitymodel of identity based multi-proxy signature scheme, and give the first identitybased multi-proxy signature scheme with provable security in the random oracle.4. In the end, we do research on identity based universal designated verifier signaturescheme. To our best knowledge, the security of the existing identity based universaldesignated verifier signature schemes are based on the random oracle model. How-ever, it has been shown that when random oracles are instantiated with concrete hashfunctions, the resulting scheme may not be secure. To solve this problem, we proposethe first identity based universal designated verifier signature scheme whose securitycan be proven in the standard model based on the CDH problem.