In key agreementprotocols, two or more entities agree on a session key to be used later to assure the confidentiality of the communication between them. The first protocol was proposed in 1976 by W. Diffie and M. Hellman . This protocol does not authenticate the entities, and thus suffers from man-in-the-middle attack. Different approaches have been developed to address this problem [2,3]. The use of authenticated key agreementprotocols, which provide implicit authentication, solves the problem of man-in-the middle attack. This implicit authentication is achieved by using a public key infrastructure (PKI). A PKI enables users of a basically insecure public network such as the Internet to securely and privately exchange data and money through the use of a pair of cryptographic keys that is maintained through a trusted certifying authority. One of the two keys is
Key agreementprotocols are used to exchange keys between two or multiple entities. The exchanged key can be later used to assure confidentiality through encryption. Additionally authenticated key agreementprotocols offer implicit authentication. In this paper we conduct a security and efficiency comparison of tri- partite authenticated identity-based key agreementprotocols and review all of the protocols from the group. From the security perspective the protocols are compared with respect to the level to which they comply with defined security properties for authenticated key agreementprotocols and the number of known at- tacks, whereas from the efficiency perspective the protocols are compared regarding computational effort. The comparative study enables in-depth analysis of existing protocols and the development of new ones. Povzetek: Podana je primerjava protokolov za izmenjavo kljuˇcev.
Recently, some two-party Authenticated Key Agreementprotocols over elliptic curve based algebraic groups, in the context of Identity-Based cryptography have been proposed. The main contribution of this category of protocols is to reduce the complexity of performing algebraic operations through eliminating the need to using Bilinear Pairings. In this paper, we proposed two novel Identity-Based Authenticated Key Agreementprotocols over non-symmetric role participants without using Bilinear Pairings. The results show that our proposed schemes beside of supporting security requirements of Key Agreementprotocols, require a subset of operations with low complexity in compare with related protocols in this scientific area.
In this study, we examine three tripartite authenticated key agreementprotocols. We show that these protocols do not possess the desirable security attributes. We remark that the purpose of this paper is not to investigate the design of the protocols neither to repair the security ﬂaws, but simply to show by example how diﬃcult is to design a secure cryptographic protocol.
Abstract. The group key agreement protocol enables to derive a shared session key for the remote members to communicate securely. Recently, several attempts are made to utilize group key agreementprotocols for s ecure multicasting in Internet of Things. This paper contributes to identify the security vulnerabilities in the existing protocols, to avoid them in future constructions. The protocols presented by Gupta and Biswas have been found insecure to ephemeral secret key leakage (ESL) attack and also, malicious insiders can impersonate an honest participant. Additionally, the protocol presented by Tan is also ESL-insecure. We also present a fix to the Tan’s protocol to make it secure.
Key agreementprotocols are usually designed under public key cryptography (PKC). The first practical solution to the key agreement problem is the Diffle-Hellman key exchage protocol . However, the Diffle-Hellman protocol does not provide authentication to the participants and hence subjects to the man-in-the-middle (MITM) attack. Hence, the research in this area has been focusing on the design of AKA protocols, as they offer the assurance that only the participating parties of a protocol can compute the agreed key. Over the years, a number of AKA protocols under traditional PKC have been proposed [2-4]. However, the need for PKI-supported public-key certificates is considered the main difficulty in the deployment of traditional PKC.
We've got conferred 2 completely different economical protocols, A-DTGKA and A-BD to supply echt secure communications in unexpected networks. the primary pro-tocol A-DTGKA is appropriate for networks wherever a partial structure exists or may be shaped. This additionally with the planned clump theme will give for an economical. a bunch of nodes and a controller which will have not met before and share no pre-shared secrets, type a bunch firmly to
This survey is presented to give a brief review; clear understanding about KAP which has important role in cryptography and it is a part of data security in any system. KAP is one of the hardest protocols to design, the reason for that as long as many attacks are discovered, protocols need to be verified again and there is a need to develop new one that can defend against the new attacks. The method that will be used in surveying is literature study and the most KAP topics that the survey discusses are present in Figure 1. The next section will examine what does a KAP mean and give a brief history. Security requirements of KAP are presented in second section. The third section introduces attacks that exposed to the system. The fourth section discusses the knowledge needed to design a new protocol that meets the security requirements respectively.
Since 2-party Diffie-Hellman key exchange was first proposed in 1976 , its contributory nature has attracted many cryptographers into trying to extend it to a group setting. Among those efforts, Group Diffie-Hellman (GDH) in  is thought as one of the suc- cessful extensions of Diffie-Hellman to the n-party case. There are several versions of GDH, among which GDH.2 and GDH.3 are considered as practical group protocols (see the details in ). Nevertheless, GDH cannot stand alone, as other group key distrib- ution protocols, since authentication of each peer (group member) should precede the group key sharing procedure in a practical application. Although there are useful au- thentication techniques for group communication protocols, most of them depend upon a centralized server, trusted third party. This not only increases communication costs but also deteriorates security of the protocol.
Abstract—Certificateless cryptosystems were proposed by Al-Riyami and Paterson in 2003  to solve problems of public key cryptosystems based on PKI and based on identity. Up to now, various types of certificateless cryptographic primitives as encryption functions, signature schemes, key agreementprotocols and etc, have been designed. But to the best of our knowledge, multiple-key agreementprotocols have not been proposed based on certificateless cryptosystem yet. So in this paper we propose a certificateless authenticated multiple-key agreement protocol with bilinear pairings.
Due to the high complexity of performing Pairings operation, pairing-free protocols became an attractive research area in recent years. In the scope of pairing-free Certificateless Key Agreementprotocols, several works have been proposed. In this paper, we propose a Certificateless two-party Key Agreement protocol without pairings. The significant feature of the proposed protocol is the low complexity of computations in compare with related works.
We consider several distributed collaborative key agreementprotocols for dynamic peer groups. This problem has several important characteristics which make it different from traditional secure group communication. They are distributed nature in which there is no centralized key server, collaborative nature in which the group key is contributory; i.e., each group member will collaboratively contribute its part to the global group key, and dynamic nature in which existing members can leave the group while new members may join. Instead of performing individual rekey operations, i.e., re-computing the group key after every join or leave request, we consider an interval-based approach of rekeying. In particular, we consider two distributed algorithms for updating the group key: (1) the Rebuild algorithm, (2) the Queue-batch algorithm. Performance of these distributed algorithms under different settings, such as different join and leave probabilities, is analyzed. We show that these three distributed algorithms significantly outperform the individual rekey algorithm, and that the Queue-batch algorithm performs the best among the three distributed algorithms. Moreover, the Queue-batch algorithm has the intrinsic property of balancing the computation communication workload such that the dynamic peer group can quickly begin secure group communication. This provides a fundamental understanding about establishing a collaborative group key for a distributed dynamic peer group.
Although web services aim to bring about seamless and effective communication in a wide variety of Internet applications, the interactions between them are currently limited to simple request–response exchanges. However, in the longer term we believe this is unsustainable. In particular, we believe that more complex protocols for web service conversations are necessary if the participants are to tailor their needs and offers to the prevailing context and they are to coordinate multiple services in open and realistic environments. To this end, this paper combines and extends two recent web service languages, WS-Conversation Language (WSCL) and WS-Agreement, in order to obtain a method for engineering protocols of sufﬁcient expressiveness for the next generation of ﬂexible and autonomous services. Speciﬁcally, we propose that the protocols include speech-acts as the individual messages and we show how to model such speech-acts as WS-Agreement schemas, which can, in turn, be imported into the speciﬁcation of the protocols in WSCL. To demonstrate our approach, we express a standard contracting protocol in the extended WSCL/ WS-Agreement languages. Furthermore, we use statechart notation as a visual counterpart to help developers write clients that ﬂexibly interact with a service and to help users to better understand how to interact with a service. Finally, we show that the translation between statecharts and WSCL/WS-Agreementprotocols is straightforward.
37] it is shown that information theoretic key agreement is possible without a pre- shared secret key k, but at the impractical expense of enormous storage requirements Ω( p |R|) for honest parties. The so-called Hybrid Bounded Storage Model has been considered in [5, 29]. This model suggests to use a computationally secure initial key k. Dziembowski and Maurer  showed that this approach is in general not secure, but there may exist natural initial key agreementprotocols providing everlasting security. The formalisation and security proof of such a scheme is still open. Harnik and Naor  showed that black box proofs for everlasting security in the hybrid model cannot exist. Ding  and Dodis and Smith  consider the practical problem of transmission errors, and the case of quantum adversaries has been considered in [25, 61].
A key establishment protocol allows entities to establish a common secret key to ensure secure communications over an insecure public network. This paper proposes two new two- party key agreementprotocols. Both protocols do not involve bilinear pairings. The first protocol is a certificate-based key agreement protocol that is more efficient than  due to its dependence on the elliptic curve discrete logarithm problem and the second is an extension to a certificateless key agreement protocol. Both protocols depend on the use of an authentication message to check that the shared session key is equal for both entities before using it. This authentication message prevents the key off-set attack that is valid for the Haiyan-Sun protocol . The security analysis of the second protocol is discussed. The proposed certificateless key agreement protocol is compared with other protocols in literature [2,3,4] and it requires minimal computational cost. Moreover, this protocol is implemented using the Mathematica (7) program.
There are message exchange phase and decision making phase in the consensus agreement process too. In the first round of message exchange phase, each node in the same cluster of Blevel group broadcasts the initial value obtained from inter agreement process to other nodes and receives the other node’s initial values in the same cluster. And, in the second round of message exchange phase, node i broadcasts the received values in the first round to other nodes and receives the other node’s values in the same cluster to construct a MAT Bi . In the decision making phase, a majority
This uncertainty is reflected both in the Council Decision, which fails to clarify who ex- actly are the “people concerned”, but also in the Commission’s Report on benefits for the people of Western Sahara. The latter expressly acknowledges that “the term ‘people con- cerned’ is liable to different or even divergent interpretations […] In any event, we decided to start by assessing whether the agreement helped trade between Western Sahara and the EU”. 54 By conceding this, the Commission in essence conceded that the scope of its
However, at this time, no agreement has been reached among several miRNA expression–profiling studies. Dif- ferent protocols, measurement platforms, and small sample sizes could result in incomparable expression levels. Thus, we conducted this meta-analysis to systematically evaluate the diagnostic value of miRNAs for OS diagnosis. In our study, the results showed that there were 17 unregulated and 8 downregulated miRNAs in OS patients. Additionally, we found that miRNA assays using serum specimens, with a specificity of 0.83 and DOR of 36.78, greatly improved the diagnostic accuracy compared to plasma-based assays, with a specificity of 0.91 and DOR of 86.05. Although the results are inconsistent with previous research, it was indicated that sample types might play a critical role in investigating the utility of miRNAs as biomarkers in disease diagnosis. There were some specific miRNAs that were expressed differently in different studies. Liu et al 40 reported that
For optic nerve area measurement, intra-rater differences were smaller and with less systemic error when compared to the inter-rater differences. This can likely be attributed to consistent judgement regarding segments by an individual and stems from the smaller segmentation differences. It suggests that inter-rater agreement might be improved upon by training sessions and consensus review of segmentations. For example, a training set of images of both normal and swollen eyes due to a variety of optic neuropathies could be used to calibrate raters regarding identifying the different struc- tures of the optic nerve, discerning retinal tissue from artifacts, and more confidently and consistently identify- ing BM margins. Inter-rater agreement showed less systematic error for wide angle line scans than for radial scans which might be due to better scan quality enabling easier and more consistent judgements regarding loca- tion of boundaries during segmentation.
80 The architecture is a trust-mechanism. Data is stored in isolated distributed cloud-storage centers from different cloud-providers, in this way, users can recapture the control of data originally belonging to cloud providers, and then have a higher level of centralized control of the distributed control. Combined with tolerable intrusion approaching to data protection(data-broken based on data scheme),such separate meaningless data storage lets users no longer have to worry about the security of cloud storage. In addition, the method of isolated distributed storage disperses the overall risk, with the superposition of each cloud storage service provider's own security the system has a higher security, and the simple structured distribution makes it very efficient. In the architecture, cloud computing applications in accordance with the cloud-storage service agreement (data broken protocols, data reconstruction protocols and isolated distributed agreement) can create service instances in their own cloud computing environment to call the interfaces of cloud storage services for data storage, and also can directly use the third-party services which implement the structured isolated distributed interfaces above.