Multi-signature is useful in the case that plural signers generate a signature for a single message.Most previous multi-signature schemes based on RSA only support signing in a serial order.To meet the need of signing in more complex order,we proposed a structured multi-signature scheme based on RSA.The size of the multi-signature and the multi-signature verification computational cost of are the same as that of single RSA signature scheme and the computational cost of signing is proportion to the increase of signers.The security of the proposed scheme is reduced the complexity of inverting RSA.

The scheme,called SDSA（selectively disclosing sensitive attributes）,was proposed to keep confidentiality of sensitive attributes in credential,which had the following characteristics,such as selectively disclosing sensitive attributes in credential,simple key management,no need of the secure third party.The security of SDSA is proved.The application and implementation of SDSA is illuminated through a typical example.

Ji-Yang's signcryption scheme was analyzed and its flaw was pointed out. An improved publicly verifiable signcryption scheme was proposed. Being different from existing schemes, this scheme introduced a strong anti-collision hash function to enhance the coupling of encryption and signature. In addition, hashed messages were signed using digital signature technology in proposed scheme. The proposed scheme is strong existentially unforgeable under active chosen message attack and is of strong confidentiality against outer adversary and the third party. The proposed scheme is almost as efficient as the Ji-Yang's one on both computational cost and spatial cost, also has strong confidentiality, the arbiter of anti-attack and publicity verifiable characteristics.

Signcryption is a new crypto primitive to model a process achieving privacy and authenticity. Besides privacy and authenticity, non-repudiation is also a pre-requisite property a signcryption for a signcryption scheme. We proposed a publicly verifiable short signcryption scheme which is strong existentially unforgeable under active chosen message attack and is of strong confidentiality under the active chosen cipher-text attack in the flexible unsigncryption oracle. All the security proofs is given standard model without using random oracles.

The group key management is one of the most crucial problems in group communication. In dynamic and large-scale groups, the overhead of key generating and key updating is usually relevant to the group size, which becomes a performance bottleneck in achieving scalability. Therefore, scalable group key management protocol, which is independent from group size, is the basis for wide applications of group communication. The paper proposes a novel group key management protocol, which designates un-trusted routers over Internet as transmitting nodes to organize a key material transmitting tree for transmitting key material. Members in group that are partitioned into subgroups attach to different transmitting nodes, and compute SEK using received key material and own secret parameter. The overhead of key management can be shared by the transmitting nodes which can not reveal the data of group communications, and the overhead for key management of each transmitting node is independent of the group size. In addition, the new protocol conduces to constant computation and communication overhead during key updating.

By analysing the electronic commerce protocol based on credit,the paper proposes an optimistic fair e-commerce protocol with electronic wallets.By applying the Cross Validation for encryption algorithms,the atomicity of the electronic commerce protocol can be really achieved.Towards the e-commerce protocol based on an improved DSA signature algorithm,the paper analyzes the condition of the customers’ vicious overdraft.The introduction of electronic wallet as the security control terminal effectively avoids the customers’ vicious overdraft. The whole process of the protocol is elaborated. The atomicity and security of the protocol is validated informally.

Threshold-multisignature schemes combine the properties of threshold group-oriented signature schemes and multisignature schemes.This kind of signature scheme allows a threshold t or more group members to collaboratively sign on a message and the signers’ identifications can be traced and verified.A fully distributed threshold-multisignature scheme is proposed in this paper.The scheme is developed from a proved secure single signature scheme and has the same security of its basic version.In the progress of the protocols one secure signature scheme and one secure signcryption scheme are incorporated to ensure that the protocols are secure and verifiable.The security and efficiency of the scheme and the protocols make the scheme practical.

Method for text information hiding based on part of speech (PoS) grammar is proposed. A context free PoS grammar generates PoS strings, which are patterns of natural language sentences. Taking PoS strings as a transform domain of natural language, the method maps both secret message and cover text to the domain, then maps each PoS string to a number where sentence appears in the cover text by string matching, and sequence of the numbers is the secret key. Using the secret key, receiver extracts the secret message by syntactic analysis. Further more, a formula computing the capacity of hidden information is given. This method does not require any modification of text, meanwhile, it is a sound solution of the problem cover text is syntactic but not semantic that Wayner 's scheme encountered.

This paper analysed the abstract action in automated trust negotiation and defined pattern of negotiation.Then proposed the abstract model of trust negotiation based on the first-order temporal logic.Presented the syntax and semantic meaning,which provided effective tool for realizing the automated trust negotiation systems.

The subliminal channel is used to send a secret message to an authorized receiver; the message cannot be discovered by any unauthorized receivers. Designated verifier signature(DVS) provide authentication of a message, we design a DVS scheme with message recovery mechanism and use it as a subliminal channel. In order to share a message among n users securely and allows t or more users can reconstruct the secret in dynamic groups, we combine both subliminal channel and (t, n) threshold cryptography. Then we proposed a threshold subliminal channel which can convey a subliminal message to a group of users based on message-recovery designated verifier signatures. Reconstructing the subliminal message relies on the cooperation oft or more users in the group and they can verify the validity of the subliminal message. Security and performance analysis show that the proposed scheme is secure and efficient.

Electronic voting costs less and can solve the problem of participation rate that occurs in traditional elections. Traditional E-voting schemes are designed using blind signature or anonymous communication channel; it is hard for them to solve the new problems like vacant ballot, cheating, vote collision and so on. List signature is the expansion of group signature, in which adds public detection. We proposed an E-voting scheme based on it, the proposed scheme can satisfy the properties of E-voting and can solve the new problems conveniently. Compared with the traditional schemes, it is more convenient to detect the members who issue more than one ballots in the proposed scheme. Security and performance analysis shows that the proposed scheme is secure and efficient.

In large and dense mobile Ad Hoc networks,position-based routing protocols can offer significant performance improvement over topology-based routing protocols by using location information to make forwarding decisions.Though many papers are about secure routing protocol in Ad Hoc now,few consider the security of the protocol based on location.This paper proposes the SGRP(Secure Grid Routing Protocol) which enhances the original GLS protocol.To adapt the high mobility of Ad Hoc network,SGRP completes the TESLA by adding the authentication process as new node entering networks.It uses DFA(Deterministic Finite Automaton) to explain the receiving packet process.On the other side,BAN is used to analyze the protocol's security.SGRP also proposes a reputation system,and limits inside nodes' vicious behavior.The simulation result shows that SGRP can isolate the spiteful node initiating interrupt attack effectively.

In multisignature schemes signers can sign either in a linear order or not in any specified order, but neither of them is adequate in some scenarios where require mixture using of orderless and ordered multisignature. Most order-specified multisignatures specified the orders as linear ones. In this paper, we proposed an order-specified multisignature scheme based on DSA secure against active insider attack. To our knowledge, it is the first order-specified multisignature shceme based on DSA signature scheme, in which signers can sign in flexible order represented by series-parallel graphs. In the multisignature scheme verification to both signers and signing order are available. The security of the scheme is proved by reduce to an identification scheme that is proved have some concrete security. The running time of verifying a signature is comparable to previous schemes while the running time of multisignature generation and the space needed is less than those schemes.

The (t, n) threshold cryptography is an important method for sharing a group secret message in dynamic groups such as ad hoc groups. Using subliminal channel, one can send a secret message to an authorized receiver and the message cannot be discovered by any unauthorized receivers; it satisfies different requirements of different kind of users. We discussed the security of HCW scheme and proposed a secure anonymous threshold subliminal channel. The proposed scheme has not any setup phase and allows mixture use of discrete-logarithm-type keys and RSA-type keys. Furthermore, the proposed scheme only has a simple initialization phase, thus, it is flexible and suitable for ad hoc environments. The new scheme can resist forgery and conspiracy attacks; the subliminal message sender is indistinguishable to others except the authorized users. Performance analysis and experiments show that the new scheme is more efficient in general

Threshold signature schemes are useful in MANET because of the mobility and weak connectivity. Meanwhile, order-specified multi-signature schemes are valuable in some multi-level security systems. To meet such kind of requirements, we proposed a secure threshold order-specified multi-signature scheme based on RSA in this paper. The scheme is designed based on a modified threshold RSA signature scheme and an order-specified. It has a certain extent exact security. Proof is given in the random oracle model and the computational and spatial complexity are presented at the end.

Strong security in public key cryptography is not enough; the encryption has to be achieved in an efficient way. OAEP or SAEP is only suitable for special applications (e. g. key transport), and securely transporting message of any length is a challenge. Motivated by the hybrid encryption, we present a practical approach to achieve the (adaptively) chosen ciphertext security. The time cost of encryption/decryption of proposed scheme is similar to OAEP and the bandwidth of message recovery is 92% for standard security parameter, while RSA-OAEP is 84%. The scheme is also provably secure against adaptively chosen ciphertext attacks in the random oracle model. We conclude that the approach is practical in more extensive application.

An efficient two party RSA secret key sharing generation scheme based on a homomorphic encryption, which is semantically secure under the prime residuosity assumption, is proposed in this paper. At the stage of computing RSA moduloN, an initial distributed primality test protocol is used to reduce the computation complexity and increase the probability ofN being a two-prime product. On the other aspect, the homomorphic encryption based sharing conversion protocols is devised and adopted in multi-party computing modulusN and secret keyd. Comparing to any sharing conversion protocols based on oblivious transfer protocol, the homomorphic encryption based sharing conversion protocols are of high performance. Our scheme resists the passive attack and since a method of verifying the sharing was introduced in, the scheme can resists any cheating behaviors too. Security proof, computation complexity and communication complexity analysis are given at last.

The paper analyses the security solutions to WLAN. Because the calculation capability of the mobile equipment in WLAN is relatively weak, the paper presents the scheme of the third party authentication based on the symmetric cryptosystem to solve the identity authentication and key exchange between STA and AP in IPSec. The plan has small calculation quantity, and can satisfy the characteristics of WLAN.

软件测试过程中的一个重要任务是生成测试用例,但目前有些测试用例生成方法存在的一些问题限制了它们的使用,如利用动态测试用例生成方法获取合适的测试用例需要进行大量的迭代.提出了一种在面向路径的测试用例生成中使用熟知的二分搜索策略生成测试用例的形式化体制,同时设计了一种测试用例二分搜索算法.该算法确定一个测试用例的迭代次数被限制在O(mnlog|D|)内.

Contrast with current WLAN (wireless local area network) security mechanism worked in data link layer. IPSec worked in IP layer is applied in WLAN as a security technology which is used in wired network has his superiorities. But IPSec uses Internet key exchange protocol (IKE) as default that need to a large number of computations is not fit for mobile devices of WLAN. This paper puts forward that using the third party authentication of symmetric algorithms to replace the major mode of the IKE first phase and maintain IKE original process of second phase basically. Doing so not only satisfy the WLAN application background but also maintain the original basic functions of IKE. We rename the improvement IKE to WKE (wireless key exchange). Theory analysis and experiment represent WKE has low calculation. It can improve the execution efficiency of the identity authentication and key negotiation between wireless station and IPSec security gateway.