Biblio

To ensure traffic safety and proper operation of vehicular networks, safety messages or beacons are periodically broadcasted in Vehicular Adhoc Networks (VANETs) to neighboring nodes and road side units (RSU). Thus, authenticity and integrity of received messages along with the trust in source nodes is crucial and highly required in applications where a failure can result in life-threatening situations. Several digital signature based approaches have been described in literature to achieve the authenticity of these messages. In these schemes, scenarios having high level of vehicle density are handled by RSU where aggregated signature verification is done. However, most of these schemes are centralized and PKI based where our goal is to develop a decentralized dynamic system. Along with authenticity and integrity, trust management plays an important role in VANETs which enables ways for secure and verified communication. A number of trust management models have been proposed but it is still an ongoing matter of interest, similarly authentication which is a vital security service to have during communication is not mostly present in the literature work related to trust management systems. This paper proposes a secure and publicly verifiable communication scheme for VANET which achieves source authentication, message authentication, non repudiation, integrity and public verifiability. All of these are achieved through digital signatures, Hash Message Authentication Code (HMAC) technique and logging mechanism which is aided by blockchain technology.

With the developing of computer technology, Convolutional Neural Network (CNN) has made big development in both application region and research field. However, CAPTCHA (one Turing Test to tell difference between computer and human) technology is also widely used in many websites verification process and it has received great attention from researchers. In this essay, we introduced the CNN based on tensorflow framework and use the MINIST data set which is used in handwritten digit recognition to analyze the parameters and the structure of the CNN model. Moreover, we use different activation functions and compares them with different epochs. We also analyze many problems during the experiment to make the original data and the result more accurate.

Digital signatures are increasingly used today. It replaces wet signature with the development of technology. Elliptic curve digital signature algorithm (ECDSA) is used in many applications thanks to its security and efficiency. However, some mathematical operations such as inversion operation in modulation slow down the speed of this algorithm. In this study, we propose a more efficient and secure ECDSA. In the proposed method, the inversion operation in modulation of signature generation and signature verification phases is removed. Thus, the efficiency and speed of the ECDSA have been increased without reducing its security. The proposed method is implemented in Python programming language using P-521 elliptic curve and SHA-512 algorithm.

Although many digital signature algorithms are available nowadays, the speed of signing and/or verifying a digital signature is crucial for different applications. Some algorithms are fast for signing but slow for verification, but others are the inverse. Research efforts for an algorithm being fast in both signing and verification is essential. The traditional GOST algorithm has the shortest signing time but longest verification time compared with other DSA algorithms. Hence an improvement in its signature verification time is sought in this work. A modified GOST digital signature algorithm variant is developed improve the signature verification speed by reducing the computation complexity as well as benefiting from its efficient signing speed. The obtained signature verification execution speed for this variant was 1.5 time faster than that for the original algorithm. Obviously, all parameters' values used, such as public and private key, random numbers, etc. for both signing and verification processes were the same. Hence, this algorithm variant will prove suitable for applications that require short time for both, signing and verification processes. Keywords— Discrete Algorithms, Authentication, Digital Signature Algorithms DSA, GOST, Data Integrity

Named Data Networking (NDN) is an emerging network architecture, which is built by keeping data as its pivotal point. The in-network cache, one of the important characteristics, makes data packets to be available from multiple locations on the Internet. Hence data access control and their enforcement mechanisms become even more critical in the NDNs. In this paper, we propose a novel encryption-based data access control scheme using Role-Based Encryption (RBE). The inheritance property of our scheme provides a natural way to achieve efficient data access control over hierarchical content. This in turn makes our scheme suitable for large scale real world content-centric applications and services such as Netflix. Further, the proposed scheme introduces an anonymous signature-based authentication mechanism to reject bogus data requests nearer to the source, thereby preventing them from entering the network. This in turn helps to mitigate better denial of service attacks. In addition, the signature mechanism supports unlinkability, which is essential to prevent leakages of individual user's access patterns. Another major feature of the proposed scheme is that it provides accountability of the Internet Service Providers (ISPs) using batch signature verification. Moreover, we have developed a transparent and secure dispute resolution and payment mechanism using smart-contract and blockchain technologies. We present a formal security analysis of our scheme to show it is provably secure against Chosen Plaintext Attacks. We also demonstrate that our scheme supports more functionalities than the existing schemes and its performance is better in terms of computation, communication and storage.

In order to solve the problem of data leakage and tampering in end-to-end power data security management, this paper proposes a Blockchain-based power terminal data security management model, which includes power terminals and Blockchain nodes. Among them, the power terminal is responsible for the collection of front-end substation data; the Blockchain node is responsible for data verification and data storage. Secondly, the data security management mechanism of power terminal based on Blockchain is proposed, including data aggregation, data encryption and transmission, signature verification for single Blockchain, aggregation signature for main Blockchain nodes, and intelligent contract storage. Finally, by applying the mechanism to the data storage process and data request process analysis, the data management mechanism proposed in this paper has a good application effect.

A strong designated verifier signature (SDVS) scheme only permits an intended verifier to validate the signature by employing his/her private key. Meanwhile, for the sake of signer anonymity, the designated verifier is also able to generate a computationally indistinguishable transcript, which prevents the designated verifier from arbitrarily transferring his conviction to any third party. To extend the applications of conventional SDVS schemes, in this paper, we propose a group-oriented strong designated verifier signature (GO-SDVS) scheme from bilinear pairings. In particular, our scheme allows a group of signers to cooperatively generate a signature for a designated verifier. A significant property of our mechanism is constant-size signatures, i.e., the signature length remains constant when the number of involved signers increases. We also prove that the proposed GO-SDVS scheme is secure against adaptive chosen-message attacks in the random oracle model and fulfills the essential properties of signer ambiguity and non-transferability.

Today, Smartphone is a necessary device for people connected to the Internet world. But user privacy and security are still playing important roles in the usage of mobile devices. The user was asked to enter related characters, numbers or drawing a simple graphic on the touch screen as passwords for unlocking the screensaver. Although it could provide the user with a simple and convenient security authentication mechanism, the process is hard to protect against the privacy information leakage under the strict security policy. Nowadays, various keypad lock screen Apps usually provides different type of schemes in unlocking the mobile device screen, such as simple-customized pattern, swipe-to-unlock with a static image and so on. But the vulnerability could provide a chance to hijacker to find out the leakage of graphic pattern information that influences in user information privacy and security.This paper proposes a new graphic pattern authentication mechanism to enhance the strength of that in the keypad lock screen Apps. It integrates random digital graphics and handwriting graphic input track recognition technologies to provide better and more diverse privacy protection and reduce the risk of vulnerability. The proposed mechanism is based on two factor identification scheme. First of all, it randomly changes digital graphic position based on unique passwords every time to increase the difficulty of the stealer's recording. Second, the input track of handwriting graphics is another identification factor for enhancing the complex strength of user authentication as well.

Forward secure proxy signature (FoSPS) solves the security drawback of private key exposure problem of generating the private key of each time interval. Directed signature scheme solves the public signature verification problem in traditional digital signature by designating the constant one as the signature verifier. Due to excellent properties, the two signature schemes have attracted the research of many experts. Recently, based on the Elliptic curve cryptography (ECC), a new FoSPS scheme and directed signature scheme were proposed. In this paper, we analyze the two schemes and present which the either of both schemes is insecure and do not satisfy the unforgeability. In other words, anyone is able to forge a valid signature but the one does not know the signer's secret key. In the same time, we give the main reasons why the enemy is able to forge the signature by analyzing the two schemes respectively. And we also present a simple improvement idea to overcome existing problems without adding extra computational cost which can make them applied in some environments such as e-medical information system.

Digital signatures are replacing paper-based work to make life easier for customers and employees in various industries. We rigorously use RSA and Elliptic Curve Cryptography (ECC) for public key cryptographic algorithms. Nowadays ECDSA (Elliptical Curve Digital Signature Algorithm) gaining more popularity than the RSA algorithm because of the better performance of ECDSA over RSA. The main advantage of ECC over RSA is ECC provides the same level of security with less key size and overhead than RSA. This paper focuses on a brief review of the performance of ECDSA and RSA in various aspects like time, security and power. This review tells us about why ECC has become the latest trend in the present cryptographic scenario.

Malware authors attempt to obfuscate and hide their code in its static and dynamic states. This paper provides a novel approach to aid analysis by intercepting and capturing malware artifacts and providing dynamic control of process flow. Capturing malware artifacts allows an analyst to more quickly and comprehensively understand malware behavior and obfuscation techniques and doing so interactively allows multiple code paths to be explored. The faster that malware can be analyzed the quicker the systems and data compromised by it can be determined and its infection stopped. This research proposes an instantiation of an interactive malware analysis and artifact capture tool.

We consider a generic model of Client-Server interactions in the presence of Sender and Relay, conceptual agents acting on behalf of Client and Server, respectively, and modeling cloud service providers in the envisaged "QoS as a Service paradigm". Client generates objects which Sender tags with demanded QoS level, whereas Relay assigns the QoS level to be provided at Server. To verify an object's right to a QoS level, Relay detects its signature that neither Client nor Sender can modify. Since signature detection is costly, Relay tends to occasionally skip it and trust an object; this prompts Sender to occasionally launch a Fake VIP attack, i.e., demand undue QoS level. In a Stackelberg game setting, Relay employs a trust strategy in the form of a double-blind reputation scheme so as to minimize the signature detection cost and undue QoS provision, anticipating a best-response Fake VIP attack strategy on the part of Sender. We ask whether the double-blind reputation scheme, previously proved resilient to a probabilistic Fake VIP attack strategy, is equally resilient to more intelligent Sender behavior. Two intelligent attack strategies are proposed and analyzed using two-dimensional Markov chains.

Completely Automated Public Turing Test to Tell Computers and Humans Apart (CAPTCHA) is an important human-machine distinction technology for website to prevent the automatic malicious program attack. CAPTCHA recognition studies can find security breaches in CAPTCHA, improve CAPTCHA technology, it can also promote the technologies of license plate recognition and handwriting recognition. This paper proposed a method based on Convolutional Neural Network (CNN) model to identify CAPTCHA and avoid the traditional image processing technology such as location and segmentation. The adaptive learning rate is introduced to accelerate the convergence rate of the model, and the problem of over-fitting and local optimal solution has been solved. The multi task joint training model is used to improve the accuracy and generalization ability of model recognition. The experimental results show that the model has a good recognition effect on CAPTCHA with background noise and character adhesion distortion.