Provably Secure Short Proxy Signature Scheme from Bilinear Maps

An enhanced formal model of security for proxy signature schemes is presented and a provably secure short proxy signature scheme is proposed from bilinear maps. The proposed proxy signature scheme is based on two short secure signature schemes. One is used for delegating the signing rights and computing the standard signature; the other is used for computing proxy signature. Finally, a security proof of the proposed proxy signature scheme is showed by reducing tightly the security of the proposed proxy signature scheme to the security of the two basic signature schemes. The proposed proxy signature scheme has the shortest ordinary signatures and proxy signatures. Moreover, the proxy signature generation needs no pairing operation and verification needs just two pairing operation.

Ciphertext-Policy Attribute-Based Encryption for General Circuits from Bilinear Maps

In this paper, we present the first ciphertext-policy attribute-based encryption （CP-ABE） scheme for polynomial-size general circuits based on bilinear maps which is more suitable for practical use and more efficient than multilinear maps. Our scheme uses a top-down secret sharing and FANOUT gate to resist the ＂backtracking attack＂ which is the main barrier expending access tree to general circuit. In the standard model, selective security of our scheme is proved. Comparing with current scheme for general circuits from bilinear maps, our work is more efficient.

A New Process and Framework for Direct Anonymous Attestation Based on Symmetric Bilinear Maps

For the problem of the original direct anonymous attestation （DAA） scheme＇s complexity and great time consumption, a new DAA scheme based on symmetric bilinear pairings is presented, which gives a practical solution to ECC-based TPM in protecting the privacy of the TPM. The scheme still includes five procedures or algorithms： Setup, Join, Sign, Verify and Rogue tagging, but gets rid of zero-knowledge proof and takes on a new process and framework, of which the main operations are addition, scalar multiplication and bilinear maps on supersingular elliptic curve systems. Moreover, the scheme adequately utilizes the properties of bilinear maps as well as the signature and verification of the ecliptic curve system itself. Compared with other schemes, the new DAA scheme not only satis- fies the same properties, and shows better simplicity and high effi- ciency. This paper gives not only a detailed security proof of the proposed scheme, but also a careful performance analysis by comparing with the existing DAA schemes.

Practical Identity-Based Aggregate Signature from Bilinear Maps

A new identity-based （ID-based） aggregate signature scheme which does not need any kind of interaction among the signers was proposed to provide partial aggregation. Compared with the existing ID-based aggregate signatures, the scheme is more efficient in terms of computational cost, Security in the random oracle model based on a variant of the computation Diflle-Hellman （CDH） problem is captured.

An Improved Traitor Tracing Scheme Based on Bilinear Map

T6 et al presented a bilinear-map-based traitor tracing scheme（TSZ scheme） with revocation, but it is a symmetric scheme because it does not provide non-repudiation. In this paper, an improved TSZ scheme was proposed by using oblivious polynomial evaluation （OPE） protocol and service parameters. Under the recondition of general sameness capabilities of both TSZ and improved TSZ scheme, the new scheme adds some advantages such as providing multi-service capability, user＇s non-repudiation and data provider＇s no-framing innocent users. Furthermore, it is also proved to be semantically secure under the decisional bilinear Diffie-Hellman （DBDH problem） assumption.

Implementing Broadcast Encryption Scheme Using Bilinear Map and Group Characteristic

This paper introduced a novel method for implementing broadcast encryption. Our scheme takes advantages of bilinear map and group characteristic, and shifts most of the storage overhead to the public device instead of storing in the tamper-proof device which is a major problem on current implementation. Furthermore, the broadcast keys in our scheme could be reused periodically resulting in more operational efficiency.

PATTERN MAPPING ON BETA-SPLINE SURFACES——BILINEAR MAPPING METHOD

Texture pattern mapping is one of the most important techniques for high quality image syn- thesis. It can largely enhance the visual richness of raster-scan images. In this paper is presented a new method of mapping planar texture pattern onto beta-spline curved surfaces——bilinear mapping method which can map planar texture pattern onto curved surfaces with less distortion, and also can fulfill the geometric transformation of the texture pattern on the curved surfaces by operating the pattern win- dow. It is valuable to both CAD/CAM in artistic field and computer graphics.

Alliance-Authentication Protocol in Clouds Computing Environment

Security has been regarded as one of the hardest problems in the development of cloud computing. This paper proposes an AllianceAuthentication protocol among Hybrid Clouds that include multiple private clouds and/or public clouds. Mu tual authentication protocol among entities in the IntraCloud and InterCloud is proposed. Blind signature and bilinear mapping of automorphism groups are adopted to achieve the InterCloud Alli anceAuthentication, which overcome the complexi ty of certificate transmission and the problem of communication bottlenecks that happen in tradi tional certificatebased scheme. Blind key, instead of private key, is adopted for register, which avoids

Forward-Secure Digital Signature Scheme with Tamper Evidence

Based on the definition of tamper evidence, the authors define a new notion of tamper evidence forward secure signature scheme （TE-FSig）, and propose a general method to build a TE-FSig scheme. Based on this method, they also give out a concrete instance. A TE-FSig scheme is constructed by the standard signature scheme, forward secures signature scheme and the aggregate signature scheme. It has an additional property of tamper evidence besides the property of forward secure, which can detect the time period when the key is exposed. In the standard model, the scheme constructed in the paper is proved to satisfy the prop- erties of forward secure, strong forward tamper-evidence secure, and strongly unforgeable under the chosen-message attack.

A Practical Group Key Management Algorithm for Cloud Data Sharing with Dynamic Group

Cloud data sharing service, which allows a group of people to work together to access and modify the shared data, is one of the most popular and efficient working styles in the enterprises. However, the cloud server is not completely trusted, and its security could be compromised by monetary reasons or caused by hacking and hardware errors. Therefore, despite of having advantages of scalability and flexibility, cloud storage service comes with privacy and the security concerns. A straightforward method to protect the user's privacy is to encrypt the data stored at the cloud. To enable the authenticated users to access the encrypted cloud data, a practical group key management algorithm for the cloud data sharing application is highly desired. The existing group key management mechanisms presume that the server is trusted. But, the cloud data service mode does not always meet this condition. How to manage the group keys to support the scenario of the cloud storage with a semi-trusted cloud server is still a challenging task. Moreover, the cloud storage system is a large-scale and open application, in which the user group is dynamic. To address this problem, we propose a practical group key management algorithm based on a proxy re-encryption mechanism in this paper. We use the cloud server to act as a proxy tore-encrypt the group key to allow authorized users to decrypt and get the group key by their private key. To achieve the hierarchical access control policy, our scheme enables the cloud server to convert the encrypted group key of the lower group to the upper group. The numerical analysis and experimental results further validate the high efficiency and security of the proposed scheme.

An Efficient Certificateless Aggregate Signature Scheme

Aggregate signature can aggregate n signatures on n messages from n signers into a single signature that convinces any verifier that n signers sign the n messages, respectively. In this paper, by combining certificateless public key cryptography and aggregate signatures, we propose an efficient certificateless aggregate signature scheme and prove its security. The new scheme is proved secure against the two representative types adversaries in certificateless aggregate signature under the assumption that computational Diffie-Hellman problem is hard. Furthermore, from the comparison of the computation cost of the new scheme with some existing certificateless aggregate signature schemes in group sum computation, scalar multiplication computation, Hash computation and abilinear pairings computation, it concludes that the new scheme reduces the computation cost in scalar multiplication computation in half and maintains the same in the other computation costs.

A New Certificateless Public Key Encryption Scheme

Certificateless public key cryptography （CL-PKC） enjoys the advantage of identity based cryptography without suffering from its inherent key escrow problem. In this paper, a new efficient certificateless public key encryption scheme is proposed and its security can reach chosen-ciphertext （CCA2） secure in the random oracle model assuming the CDH and p-BDHI problem are difficult. A comparison shows that the efficiency of the proposed scheme is better than all known paring-based certificateless public key encryption schemes in the random oracle model.

Certificateless key-insulated signature without random oracles

Leakage of the private key has become a serious problem of menacing the cryptosystem security. To reduce the underlying danger induced by private key leakage, Dodis et al.(2003) proposed the first key-insulated signature scheme. To handle issues concerning the private key leakage in certificateless signature schemes, we devise the first certificateless key-insulated signature scheme. Our scheme applies the key-insulated mechanism to certificateless cryptography, one with neither certificate nor key escrow. We incorporate Waters (2005)’s signature scheme, Paterson and Schuldt (2006)’s identity-based signature scheme, and Liu et al.(2007)’s certificateless signature scheme to obtain a certificateless key-insulated signature scheme. Our scheme has two desirable properties. First, its security can be proved under the non-pairing-based generalized bilinear Diffie-Hellman (NGBDH) conjecture, without utilizing the random oracle model; second, it solves the key escrow problem in identity-based key-insulated signatures.

Improved certificateless multi-proxy signature

Multi-proxy signature is a scheme that an original signer delegates his or her signing capability to a proxy group. In the scheme, only the cooperation of all proxy signers in the proxy group can create a signature on behalf of the original signer. Jin and Wen firstly defined the formal security model of certificateless multi-proxy signature （CLMPS） and proposed a concrete CLMPS scheme. However, their construction model is inaccurate, the concrete signature scheme has has three problems： the definition of the strengthened security a security flaw, and the proof of the security is imperfect. With further consideration, a remedial strengthened security model is redefined, and an improved scheme is also proposed, which is existentially unforgeable against adaptively chosen-warrant, chosen-message and chosen-identity attacks in the random oracles. In this condition, the computational Diffie-Hellman （CDH） assumption is used to prove full security for our CLMPS scheme.

A Hierarchical Attribute-Based Encryption Scheme

According to the relation of an attribute set and its subset,the author presents a hierarchical attribute-based encryption scheme in which a secret key is associated with an attribute set.A user can delegate the private key corresponding to any subset of an attribute set while he has the private key corresponding to the attribute set.Moreover,the size of the ciphertext is constant,but the size of private key is linear with the order of the attribute set in the hierarchical attribute-based encryption scheme.Lastly,we can also prove that this encryption scheme meets the security of IND-sSETCPA in the standard model.

ID-Based Public Auditing Protocol for Cloud Storage Data Integrity Checking with Strengthened Authentication and Security

Cloud storage service reduces the burden of data users by storing users＇ data files in the cloud. But, the files might be modified in the cloud. So, data users hope to check data files integrity periodically. In a public auditing protocol, there is a trusted auditor who has certain ability to help users to check the integrity of data files. With the advantages of no public key management and verification, researchers focus on public auditing protocol in ID-based cryptography recently. However, some existing protocols are vulnerable to forgery attack. In this paper, based on ID-based signature technology, by strengthening information authentication and the computing power of the auditor, we propose an ID-based public auditing protocol for cloud data integrity checking. We also prove that the proposed protocol is secure in the random oracle model under the assumption that the Diffie-Hellman problem is hard. Furthermore, we compare the proposed protocol with other two ID-based auditing protocols in security features, communication efficiency and computation cost. The comparisons show that the proposed protocol satisfies more security features with lower computation cost.

An Introduction to the Computational Complexity of Matrix Multiplication

This article introduces the approach on studying the computational complexity of matrix multiplication by ranks of the matrix multiplication tensors.Basic results and recent developments in this area are reviewed.