On the Insecurity of a Server-Aided RSA Protocol

The verifiable implicit asking is to speed up a certain feasible computation (e.g., y=x d mod n) based on a secret (d) stored in a relatively powerless device (called Client) with the help of powerful device(s) (called Server(s)) in such a way that Client can check the behavior of Server(s) and that the leakage of the secret to Server(s) should be suppressed as much as possible. Possible attacks to obtain Client's secret are classified into passive and active attacks. Passive attacks can be completely nullified by dividing the target computation into two parts so that one depends on d but the other does not and then by asking Server to do only the latter part. However since such a method brings relatively low speed-up performance, we discuss a method to obtain verifiable implicit asking protocols highly secure against passive attacks by modifying some base protocols which are fast enough but not completely free from passive attacks since sending to Server some information not independent from d.KeywordsSmart CardActive AttackTarget ComputationAddition ChainPassive AttackThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Many side channels including power consumption, electromagnetic emanation, optical radiation, and even sound have been studied since the first publication of a side channel attack at the end of the 1990s. Most of these channels can be relatively easily used for an overall analysis of the cryptographic system (implementation of efficient passive attacks) or for injection of faults. Until recently, only the optical channel allowed both analysis of locally leaked information and precise injection of faults (single-bit errors). Recent works showed that the near-field electromagnetic channel enables similar results to be obtained. Like the optical channel, the near-field electromagnetic channel allows both active and passive attacks, which, in addition, can be theoretically non-invasive and contactless. However, the cost of the attack bench that is needed to exploit the near-field electromagnetic channel is less than that of an optical channel. Recently, we showed that it is possible to use the near-field electromagnetic channel to perform an efficient active attack targeting the true random number generator (TRNG) based on ring oscillators. In cryptography, TRNGs are chiefly used to generate encryption keys and other critical security parameters, so the proposed active attack could have serious consequences for the security of the whole cryptographic system. Here, we present the coupling of a passive attack and an active attack. The proposed coupled attack first uses a spectral differential analysis of the TRNG electromagnetic radiation to obtain valuable information on the position of ring oscillators and their frequency range. This information is then used to tune the electromagnetic harmonic signal to temporarily synchronize the ring oscillators. In this paper, we propose a fault model of the entropy extractor which shows that the behavior of the ring oscillators changes, and that it occurs additional and unwanted “fake rising edges” of the clock signal which disturb the flip-flops involved in such TRNGs. The effectiveness of our proposed coupled attack questions the use of ring oscillators in the design of TRNGs.

In this study, by exploiting the properties of finite‐length polar codes, the authors introduce a physical layer encryption scheme to make secure (from a computational security perspective) and efficient communication between a sender (Alice) and a legitimate receiver (Bob) against both active and passive attacks, simultaneously. To prevent active attacks, two techniques are considered: (i) a novel method is introduced to keep the generator matrix of polar code secret from an active attacker (Oscar); (ii) a proper joint polar encoding/encryption algorithm based on the hidden generator matrix is introduced. Two additional strategies are considered against passive attacks: (i) a new method is introduced to partition the bit‐channels into good and bad bit‐channels and then the scrambled information bits are transmitted over those bit‐channels that are good for Bob but bad for a passive attacker (Eve); (ii) the secret key cryptography is implemented at the physical layer, such that Eve cannot decode the eavesdropped data without the knowledge of the secret key shared between the authorised parties. Besides, this study discusses efficiency analysis results consisting key size, error performance and computational complexity of the proposed scheme.

Identification scheme is a cryptographic authentication protocol which allows a client to convince the corresponding server on the authenticity of his identity, without the need to share his secret with the server. In this paper, we cryptanalyze two identification schemes and show that they are not secure against impersonation under passive attack. We also propose a fix for one of the schemes to upgrade their security to secure against impersonation under passive, active and concurrent attacks.

In both wireless and mobile ad hoc networks, assaults can come from a variety of different sources. The terms "active attack" and "passive attack" describe these two types of attacks. In the network community, the Sybil attack is one of the most often used and deployed techniques for sniffing identities and repurposing them. Multiple identities or Sybil attacks have recently sparked a lot of interest in the research community. The algorithms and networks on which they are tested are vastly different among the many methods that have been offered. Since researchers can't evaluate these systems side by side or test their efficacy on real-world social networks with a variety of structural features, it's difficult to say whether there are any other (perhaps more efficient) methods of Sybil protection. In the event of a Sybil attack, the gatecrasher subverts the system framework's notoriety arrangement by creating a large number of pseudonymous individuals and then using them to add an enormously imbalanced influence. Three factors determine a notoriety framework's susceptibility to a Sybil attack: how quickly personalities can be generated, how much the notoriety framework accepts inputs from substances that lack a chain of trust, and if the notoriety framework handles all components equally. A large-scale Sybil ambush in Bittorrent Mainline may be accomplished in a cheap and effective manner, according to confirmation. A substance on a distributed system is a piece of software that has access to the resources of the local community. By displaying a character, a distributed system element reveals itself to the world. A single chemical can have an impact on more than one character. Numerous characters can be assigned to a single element. The personalities of substances in shared systems are used for the objectives of repetition, asset transfer, reliability, and trustworthiness, among other reasons. For remote elements to be aware of characters without necessarily being aware of the personality-to-neighborhood correlation, distributed systems make use of the character as a decision. Each different identification is normally considered to be associated with a separate local entity by convention. A single local entity may have several identities in actuality. In order to avoid and identify Sybil assaults, an empirical technique is used in this study. According to the base paper, any nodes with RSS greater than the provided threshold are regarded to be attackers under the present approach. A centralized way to monitor the mobile nodes is required to prevent this assault. As the server agent assumes full control of the ad-hoc network, malevolent nodes or selfish nodes are fully eliminated from the system.

For the intrinsic characteristics cause several vulnerabilities of MANET, anonymous routing protocol attracts much more attention in secure mobile ad hoc networks for the purposes of security and privacy concerns. Until recently, lots of anonymous routing protocols have been proposed. However, most of them are single path or use one path at a time or can not thwart both the passive attacks and active attacks simultaneously. Thus, we propose an anonymous multipath routing protocol based on secret sharing. The protocol provides identity anonymity, location anonymity, data and traffic anonymity based on cryptograph technology and secret sharing in MANET communication. Meanwhile, we also introduce hash function to detect active attacks in our data transmission process. The protocol can effectively thwart the various passive attacks and reduce the successful probability of active attacks such as intercept and physical destroy attacks. In addition, Simulation results show that our scheme provides a reasonably good level of security and performance.

Mobile Ad hoc Networks (MANET) comprises of self-organizing autonomous mobile nodes. MANETs are open and decentralized. Therefore they are vulnerable to malicious entities. MANETs are multi-hop wireless network where all nodes supportively maintain network connectivity without a centralized infrastructure. Since MANETs are infrastructure less and independent, the secure communication is the main issue. Therefore they are vulnerable to malicious entities. Here the location identity and traffic can be traced out by an outside observer. Anonymity means secure communications by hiding node identities and preventing traffic analysis attacks by outside observers. This paper proposes Position based Anonymous Routing Scheme in MANETs (PARS).Here the routing is based on Greedy Perimeter Stateless Routing Protocol. The objective is an anonymous routing protocol for the network. The proposed one is a zone based anonymous GPSR based protocol that can provide source, destination and route anonymity. Performance of the proposed system is compared with that of GPSR and AODV using Network Simulator. Index Terms: Anonymous routing, position-based routing, random forwarder, zone partition. I. Introduction Mobile Ad hoc Networks are collection of independent mobile nodes that can communicate by radio waves. It is an infrastructure less self-organizing network. The nodes that are in radio range can communicate by single hop or by multi hop with the help of intermediate nodes. The network is open and decentralized and fully distributed. So they are perfect choice for communication and information sharing. MANETs are susceptible to malicious entities that aim to alter and analyzed the traffic analysis by communication eaves dropping or attacking routing protocols. MANETs are characterized by their distributed operation, multi hop routing, dynamic topology and shared physical medium. Nodes in a MANET are independently free to move in any direction. Due to the lack of a centralized coordinator security is the major concern here. Wireless communication can endure interferences or malicious interceptions; whereas multi-hop communication assumes that each node will perform properly its functions to support network services. Further, self-organization increases the complexity of security management operations as access control, node authentication, secure routing and cryptographic key distribution. There is no fixed infrastructure and the topology is frequently changing due to node mobility or environmental changes. Therefore, it is very hard to maintain a stable and efficient end-to-end route in an ad-hoc network. Each node in MANET is energy constrained. There is verylimited physical security in MANET. The type of attacks can be Active attacks or Passive attacks. The common security issues are Passive attacks which include eaves dropping and information disclosure. Active attacks include Do Sand Data modification. There are other more specific problems with mobile ad hoc network such as vulnerability of channels and nodes, Byzantine black hole and Byzantine wormhole attack. The security issue also includes attacks that may inject erroneous routing information and diverting network traffic thus making routing inefficient. There are many methods to reduce the impact of these attacks, which include a secure routing using public and private key s to get a certification authority and use of digital signatures and prior it rust relationships. Routing is the process of communication from one node to the other host in a network. Routing is the process off or warding packet towards its destination using most efficient path. Routing efficiency is measured in terms of Number of hops, traffic, security, etc. Routing protocols in MANETs are divided as reactive proactive and hybrid. Reactive Protocol maintains the routes in on demand manner. In route discovery phase it floods the route request (RREQ) packets throughout the network. Dynamic source Routing (DSR), ad hoc on- demand distance vector routing (AODV) are some of the examples of reactive protocols. In proactive approach every node in the MANET continuously maintains the complete routing information of the entire network. This is accomplished by flooding network periodically with network status information. Global State Routing (GSR), Hierarchical State Routing (HSR) and Destination Sequenced Distance Vector Routing (DSDV) are some of the examples of proactive

Many operators of cellphone networks now offer location-based services to their customers, whereby an operator often outsources service provisioning to a third-party provider. Since a person's location could reveal sensitive information about the person, the operator must ensure that the service provider processes location information about the operator's customers in a privacy-preserving way. So far, this assurance has been based on a legal contract between the operator and the provider. However, there has been no technical mechanism that lets the operator verify whether the provider adheres to the privacy policy outlined in the contract. We propose an architecture for location-based services based on Trusted Computing and Secure Logging that provides such a technical mechanism. Trusted Computing lets an operator query the configuration of a location-based service. The operator will hand over location information to the service only if the service is configured such that the service provider cannot get access to location information using software-based attacks. This includes passive attacks, where the provider monitors information flowing into and out of its service, and active attacks, where the provider modifies or injects customer queries to the service. We introduce several requirements that must be satisfied by a location-based service to defend against passive attacks. Furthermore, we present Secure Logging, an auditing mechanism to defend against active attacks.

User authentication is necessary to secure the data and process on internet or mobile communications. Most commonly employed system for said purpose is Static alpha-numeric password based authentication system. But they are susceptible to various types of active and passive attacks. One of the promising alternatives is Graphical password based authentication systems which if implemented properly are secure but not as easy to understand or learn.In this paper we propose a varied version of inkblot authentication [1] graphical password system which is secure as well as usable. It generates pseudo random one time passwords using a set of inkblots unique to the user. Properties of one time passwords ensures the resistance towards replay, phishing, shoulder surfing, active and dictionary attacks. We also analyze the results from two experiments we have conducted to confirm that this system is easy to learn and password memorability is high, thus making it a promising authentication mechanism.KeywordsUsable securityAuthenticationOne-time passwordsCueingInterfaces

Wireless sensor networks come with some very challenging demands for security – they often call for protection against active attackers trying to disrupt a network operation, but also against passive attackers looking for (potentially) sensitive information about the location of a certain node or about the movement of a tracked object. Selective forwarding is a basic yet powerful active attack. It can be detected using several existing techniques if enough information is available to an intrusion detection system. Yet when the system lacks the information due to a location privacy measure, selective forwarding detection becomes complicated. In this paper, we propose a method for detecting selective forwarding attacks and packet modification attacks concurrently with supporting location privacy. The resulting system counters a global eavesdropper capable of some active actions, such as dropping and modification of packets. We also evaluate detection accuracy of the proposed method on a small scale real-world sensor network.

Wireless sensor networks often have to be protected not only against an active attacker who tries to disrupt a network operation, but also against a passive attacker who tries to get sensitive information about the location of a certain node or about the movement of a tracked object. To address such issues, we can use an intrusion detection system and a privacy mechanism simultaneously. However, both of these often come with contradictory aims. A privacy mechanism typically tries to hide a relation between various events while an intrusion detection system tries to link the events up. This paper explores some of the problems that might occur when these techniques are brought together and we also provide some ideas how these problems could be solved.

Security is a fundamental component of every network design. When planning, building, and operating a network, you should understand the importance of a strong security policy. Network Security is a security policy that defines what people can and can't do with network components and resources. The fundamental purpose of a network security is to protect against attacks from the Internet. There are many different ways of attacking a network such as: Hacker/Cracker attacks whereby a remote Internet user attempts to gain access to a network, usually with the intention to destroy or copy data. The major attacks to network security are passive attack, active attack, distributed attack, insider attack, close: in attack, Phishing Attack, Hijack attack, Password attack etc. However a system must be able to limit damage and recover rapidly when attacks occur. So there are various solutions when any of above attacks occurs. Some of the common solutions of these attacks are firewalls, user account access controls and cryptography, Intrusion Detection Systems (IDSs), Network Address Translation (NAT), Stateful Packet Inspection etc. It is always said that "Prevention Is Better ThanCure" some most common preventions that can be taken to be secured are to keep your operating system updated and by using a reputable antivirus program.[1

In recent years, Fischlin and Fleischhacker showed the impossibility of proving the security of specific types of FS-type signatures, the signatures constructed by the Fiat-Shamir transformation, via a single-instance reduction in the non-programmable random oracle model (NPROM, for short). In this paper, we pose a question whether or not the impossibility of proving the security of any FS-type signature can be shown in the NPROM. For this question, we show that each FS-type signature cannot be proven to be secure via a key-preserving reduction in the NPROM from the security against the impersonation of the underlying identification scheme under the passive attack, as long as the identification scheme is secure against the impersonation under the active attack. We also show the security incompatibility between the security of some FS-type signatures in the NPROM via a single-instance key-preserving reduction and the underlying cryptographic assumptions. By applying this result to the Schnorr signature, one can prove the incompatibility between the security of the Schnorr signature in this situation and the discrete logarithm assumption, whereas Fischlin and Fleischhacker showed that such an incompatibility cannot be proven via a non-key-preserving reduction.

The demanding in construction of the stand-alone networks and interconnection between convergence devices have led an increase in research on Mobile Ad-hoc Network and the application of Mobile Ad-hoc Network has been paid much attention as a Ubiquitous computing which is growing fast in the field of computer science. With performance both as hosts and routers, easy network configuration, and fast response, mobile nodes participating in Mobile Ad-hoc Network are suitable for Embedded computing but have vulnerable points, about lack of dynamic network topology due to mobility, network scalability, passive attacks, and active attacks which make it impossible to manage continuous security authentication service. In this study, hashed AODV routing is used to protect from counterfeiting messages by malicious nodes in the course of path finding and setting, and disguising misrouted messages as different mobile nodes and inputting them into the network.

Information flow controls can be used to protect both data confidentiality and data integrity. The certification of the security degree of a program that runs in untrusted environments still remains an open problem in language-based security. The notion of robustness asserts that an active attacker, who can modify program code in some fixed points (holes), is not able to disclose more private information than a passive attacker, who merely observes public data. In this paper, we extend a method recently proposed for checking declassified non-interference in presence of passive attackers only, in order to check robustness by means of the weakest precondition semantics. In particular, this semantics simulates the kind of analysis that can be performed by an attacker, i.e., from the public output towards the private input. The choice of the semantics lets us distinguish between different attacks models. In this paper, we also introduce relative robustness that is a relaxed notion of robustness for restricted classes of attacks.