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We present a generator of virtual molecules that selects valid chemistry on the basis of the octet rule. Also, we introduce a mesomer group key that allows a fast detection of duplicates in the generated structures. Compared to existing approaches, our model is simpler and faster, generates new chemistry and avoids invalid chemistry. Its versatility is illustrated by the correct generation of molecules containing third-row elements and a surprisingly adept handling of complex boron chemistry. Without any empirical parameters, our model is designed to be valid also in unexplored regions of chemical space. One first unexpected finding is the high prevalence of dipolar structures among generated molecules., 24 pages, 10 figures

The broadcast nature of communication channels in infrastructureless wireless networks poses challenges to security. In this paper, we propose a novel technique namely secure multi-channel group key generation (MuGKeG) algorithm. We utilize the available channels switching behaviour between multiple nodes to hide our key from eavesdropper. We provide descriptions for an illustrative base case of three users and one eavesdropper and expand it for the case of N users with C channels and M eavesdroppers. Repeated application of the MuGKeG algorithm on the order of $$O(\log {N})$$ allows scaling the size of the group in the order of millions. We provide an analytical closed-form solution for the entropy of the secret group key generated when eavesdroppers follow an optimal attack strategy, and verify it by ns-3 simulations. Comparison with previous state-of-the-art schemes suggests that MuGKeG can provide upto 20 kbps increase in secrecy rate with a scalable key size.

Sensitive applications are split into the IP cores of the Multi-Processors System-on-Chip (MPSoCs). In order to isolate the sensitive communication among such IP cores, security zones based on conference keys agreement can be built. However, the flexibility and dynamic nature of MPSoCs force reshaping the security zones at runtime. It is still a challenge to achieve efficient computation and distribution of new conference keys in MPSoC environments. In order to solve this problem, in this work we propose the combination of two techniques: i) high performance NoC, able to efficiently communicate data and control packets in the system; and ii) hierarchical group-key management for efficient security zone modification. We implement three hierarchical protocols and we show that by decentralizing the security management of the rekeying process and using a two-level NoC, it is possible to achieve an improvement of the performance compared to the previous flat approaches.

Group Rekeying deals with the problem about how to efficiently and securely distribute a new group key GK to remaining legitimate users when there are changes in group membership (join/leave). Given a universe U of n users, an exclusive keyKS for an arbitrary subset SU is a long-term key shared by all users in US. Hence we can distribute a new group key GK encrypted under KS such that all users in U except those in S can decrypt it during group rekeying. This method allows us to exclude S from the group with a rekey message whose length is just one single encrypted key. In this paper, we use this idea to extend the famous Subset-Cover Framework to obtain its exclusive version Exclusive Subset-Cover Framework. We provide sufficient conditions that guarantee the security of any stateless group rekeying protocol in this framework. We propose a concrete exclusive subset-cover protocol called exclusive complete subtree protocol. Compared with existing 1-resilient stateless group rekeying protocols, this protocol achieves not only constant communication overhead but also better computational efficiency as well as better collusion resistance. From this protocol, it is easy to obtain a 1-resilient stateful group rekeying protocol which also outperforms the existing 1-resilient stateful protocols. Recent researches have proved some lower bounds on the communication complexity of group rekeying protocols. These bounds suggest that it is impossible to achieve a lower communication overhead without trading off some degree of collusion resistance. However, there are application scenarios which require communication overhead below these bounds. We show that any 1-resilient stateless group rekeying protocol with constant communication overhead can be used in tandem with a Subset-Cover based protocol to construct a hybrid protocol with tunable collusion-bandwidth tradeoffs.

The incorporation of electronics by embedding the relevant sensors in the physical devices in home and office, vehicles of all types, buildings in the smart cities and in all possible spheres of life form a network of devices termed as internet of things (IoT). It is being realized that vehicular ad-hoc networks (VANETs) which are responsible for the reliable and secure communication among vehicles is a primary area of research in IoT and hence ensuring security in this area is essential. Thus, this work introduces a novel approach to improve the existing authentication support to VANETs. In this proposed framework, first an anonymous authentication approach for preserving the privacy is proposed which not only performs the vehicle user’s anonymous authentication but preserves the message integrity of the transmitting messages as well. Although many anonymous authentication schemes have been proposed in VANETs until now, the existing schemes suffer from a high computation cost during the signature and certificate verification process which leads to delayed authentication. Consequently, the vehicles and roadside units (RSUs) cannot authenticate more number of vehicles per second in VANETs. Second, an efficient anonymous group key distribution protocol is proposed in this paper for securely distributing the group key to the group of vehicles in the communication range of an RSU. The RSUs can send location based information to the group of vehicles in a secure manner using this group key. Experimental analysis portrays that the results of this new privacy preserving anonymous authentication and key management schemes are promising and efficient with regard to signature verification cost and computational cost in comparison with the existing schemes.

A new type of authentication, called group authentication, has been proposed recently which can authenticate all users belonging to the same group at once in a group communication. However, the group authentication can only detect the existence of nonmembers but cannot identify who are the nonmembers. Furthermore, in a group communication, it needs not only to authenticate memberships but also to establish a group key among all members. In this paper, we propose a novel design to provide both membership authentication and group key establishment. Our proposed membership authentication can not only detect nonmembers but also identify who are the nonmembers. We first propose a basic membership authentication and key establishment protocol which can only support one-time group communication. Then, we extend the basic protocol to support multiple group communications. Our design is unique since tokens of users issued by a group manager (GM) during registration are used for both membership authentication and group key establishment.

This paper addresses the problem of managing a cryptographic group key among a large and highly dynamic group of members, who may miss group key update (rekey) messages frequently. We propose two provably-secure and practical schemes: KeyDer-GKM and ReEnc-GKM. The rekey process in these schemes has an O(log N) rekey message and O(log N) computation and storage cost for a member, where N is the number of group members. Moreover, our schemes have the following distinct features. (1) Each member is given only one private key and O(log N) public information. The private key remains unchanged during the membership period. For the public information, a member can hold them locally and update accordingly from each rekey message, or get them from a public bulletin if needed. (2) The size of published information is O(N) no matter how many rekey processes occur. The computation cost for a member, who has missed some rekey messages, to compute the up-to-date group key is always O(log N) no matter how many rekey messages have been missed. Our KeyDer-GKM scheme is very efficient since it can be implemented by using hash and XOR functions only. Our ReEnc-GKM scheme allows a member to reduce the cost of computing the up-to-date group key to one decryption by outsourcing log N operations. Both of our schemes are shown immune to the collusion attacks. For KeyDer-GKM, a set of collusive members cannot recover an unauthorized group key. For ReEnc-GKM, a set of collusive members cannot distinguish an unauthorized group key from a random string.

Two-party password-authenticated key exchange (2PAKE) protocols provide a natural mechanism for secret key establishment in distributed applications, and they have been extensively studied in past decades. However, only a few efforts have been made so far to design password-authenticated group key exchange (GPAKE) protocols. In a 2PAKE or GPAKE protocol, it is assumed that short passwords are preshared among users. This assumption, however, would be impractical in certain applications. Motivated by this observation, this article presents a GPAKE protocol without the password sharing assumption. To obtain the passwords, wireless devices, such as smart phones, tablets, and laptops, are used to extract short secrets at the physical layer. Using the extracted secrets, users in our protocol can establish a group key at higher layers with light computation consumptions. Thus, our GPAKE protocol is a cross-layer design. Additionally, our protocol is a compiler, that is, our protocol can transform any provably secure 2PAKE protocol into a GPAKE protocol with only one more round of communications. Besides, the proposed protocol is proved secure in the standard model.

Wireless personal area network (WPAN) is small-ranged network centered at an individual for interconnecting personal devices. For such a network, the bootstrapping mechanism with which the devices establish a secure group key is of critical importance. Most existing bootstrapping mechanisms require out-of-band channels and involve human interactions for authentication. In this paper, we aim to develop a fully automated bootstrapping mechanism with only in-band channels with approvable security. Toward this end, we designed an integrity-guaranteed message (IGM) structure, a self-authenticated key agreement protocol, and a prescheduling mechanism in allusion to the IEEE 802.15.4 standard for WPANs. The IGM structure guarantees that an adversary cannot modify the IGM message without being detected, thus protects the message integrity without the requirement of shared secrets between the sender and the receiver devices. The proposed self-authenticated key agreement protocol utilizes the IGM’s integrity guaranteed property, works together with the prescheduling mechanism to achieve message self-authentication, thus protecting the secure bootstrapping process from the node impersonation attack and the man-in-the-middle attack without leveraging any out-of-band channels. We analyze the security performance of the proposed schemes, and show that they can be seamless interoperative with the existing IEEE 802.15.4 standard.

Assuming the availability of an existentially unforgeable signature scheme and an (IND- CCA secure) key encapsulation mechanism, we present a generic construction for group key establishment. The construction is designed with existing proposals for post-quantum cryptography in mind. Applied with such existing proposals and assuming their security, we obtain a quantum-safe three-round protocol for authenticated group key establishment that requires only one signature per protocol participant.

As electronic communications and information services become more sophisticated, many applications involving multiple entities become necessary. Since these applications will generally require secure communications it is necessary to design protocols that establish keys for groups of principals. There is a great variety of different practical requirements that may be appropriate in different applications, and the number of protocols is very large. In this chapter we will mainly restrict attention to ways in which the two-party protocols that have been explored in previous chapters can be generalised to the multi-party situation.

Cloud computing is said to be the service oriented computing technology, which are affordable and flexible over the internet. In past few years the cloud has become more matured and provided many services, one of the primary service is data sharing in Group, where the data can be easily shared from one member to another. However, while sharing the data security is one of the primary concern. In past several methodology has been proposed. However, these methods lacked from the feasibility. Hence, in this paper we have propose methodology is based on the selection scheme. Here General Group Key is generated and moreover General Key agreement protocol is decentralized based model where the data are controlled by the owner within the same group. Moreover, the proposed methodology is evaluated by analyzing the comparative analysis based on the various number of parameter. Result Analysis suggest that our methodology simply outperforms the existing one.

Key management (KM) can be thought of as a process which assures security in various networking scenarios. It also supports establishment, revocation, and maintenance of keys among various interacting parties. Computing or generating a common secret value and distributing it among network sensor nodes is a significant goal. This key, which is called group key or conference key (CK), serves the purpose of encrypting/decrypting messages. Numerous applications are designed and recommended of wireless sensor networks to improve the security level through KM methods. A group key management (GKMP) is a process or a protocol where a shared group key is established for multiple sessions, between the cluster head and sensor nodes in a network clustering environment. The common use of this established group key (also termed as conference key) is to permit users to encrypt and decrypt particular broadcasted message that is meant for the total user group. So, without worrying, a group member can collaborate with other members about information disclosure. In this research work, existing group key management schemes have been investigated and the researcher proposes a cluster-based dynamic group key management protocol that is based on public key cryptography. A novel, dynamic, and practically applicable group key transfer protocol is proposed to offer secure communication in the network. Security analysis and computation complexity of the proposed work have also been investigated using a discrete event network simulator NS2. The experimental results demonstrate the efficiency of GKMP in resource-constrained WSNs.

Logical Key Hierarchy is a scalable and efficient method to achieve logarithmic rekeying cost in secure group communication. In applications like pay per view, video conferencing with multiple rekeying operations, the key tree will be unbalanced and will generate worst-case rekeying cost. With each join, leave operation we change the group key as well as update all keys along the key path of join/leave user. Key aspect in secure group communication is maintaining a balanced key tree and achieving logarithmic rekeying cost. In this paper, a new Strict Binary Logical Key Hierarchy rekeying algorithm is proposed. SBLKH (Strict Binary Logical Key Hierarchy) with proposed Join user algorithm and leave user algorithm maintains the balance of tree and always achieves logarithmic rekeying cost. Our experimental result shows the achieved improvement in rekeying cost of SBLKH join and leave operations compared to original LKH (Logical Key Hierarchy) join and leave operations. Rekeying cost of LKH join/leave is O(log N) and proposed SBLKH join/leave algorithm cost is O(log d), where d is the depth of tree and N is the number of users.

Security is a critical issue for medical and health care systems. Password-based group-authenticated key agreement for wireless sensor networks (WSNs) allows a group of sensor nodes to negotiate a common session key by using password authentication and to establish a secure channel by this session key. Many group key agreement protocols use the public key infrastructure, modular exponential computations on an elliptic curve to provide high security, and thus increase sensor nodes&rsquo, overhead and require extra equipment for storing long-term secret keys. This work develops a novel group key agreement protocol using password authentication for WSNs, which is based on extended chaotic maps and does not require time-consuming modular exponential computations or scalar multiplications on an elliptic curve. Additionally, the proposed protocol is suitable for multiple independent groups and ensures that the real identities of group members cannot be revealed. The proposed protocol is not only more secure than related group key agreement protocols but also more efficient.

The group key maintenance in MANET is especially risky, because repeated node movement, link breakdown and lower capacity resources. The member movement needs key refreshment to maintain privacy among members. To survive with these characteristics variety of clustering concepts used to subdivide the network. To establish considerably stable and trustable environment fuzzy based trust clustering taken into consideration with Group key management. The nodes with highest trust and energy elected as Cluster Head and it forms cluster in its range. The proposed work analyze secure multicast transmission by implementing Polynomial-based key management in Fuzzy Trust based clustered networks (FTBCA) for secure multicast transmission that protect against both internal and external attackers and measure the performance by injecting attack models.

This paper presents an approach for a secret message communication among a client–server group. In order to increase security to distribute secret message (key), we introduce splines using these at a specific permutation. We generate the key and distribute this key. This is to maintain confidentiality. Confidentiality can be achieved through changing the key material, known as re-keying every time a new member joins the group or a existing member leaves the group. The new group key is computed guaranteeing the forward and backward secrecy. Whenever there is a membership change, group key must be changed to prevent a new use from reading past communication. In proposed work, we propose how group communication must establish registration of users, entry and exit of a user. The encryption and decryption algorithm is used between the sender and the receiver. In the process, a spline is installed in the server; the server will distribute or communicate the secret messages to client based on one-to-one mapping with the help of splines; message has been encrypted and distributed to respective clients. In the client side, the decryption batch files to be installed for the verification of secret message authentication.

The problem of controlling unauthorized access to group communication requires secure distribution and maintenance of group key. In this paper, we present, implement and analyze an efficient distributed key management scheme using ternary tree for establishing secure communication in large and dynamically updating groups. The computational overhead of proposed protocol is reduced drastically since it requires only one key to transmit and only one encryption at member join. Similarly, at member leave, it requires only one key to transmit and \( {\mathcal{O}}(log_{3} n) \) encryptions. The storage and communication costs are also minimized. The proposed protocol is implemented on ternary tree based architecture and results are compared with other reference protocols. From performance analysis it is cleared that our protocol provides much better results in comparison with related protocols.

In physical-layer Group Secret-Key (GSK) generation, multiple nodes of a wireless network synthesize symmetric keys by observing a subset of their channel realizations, referred to as the common source of randomness (CSR). Unlike the case of two-user key generation, exchanging pilot symbols within the coherence-block is not sufficient to arrive at a CSR. In addition, some nodes must act as facilitators by broadcasting linear combinations of the channel realizations within the coherence-block, thereby giving rise to low-latency requirement for sharing the CSR. To assist the latency constraint, practical radio devices are forced to quantize the linear combination of channel realizations directly to finite complex constellations before broadcasting them to the other nodes. First, we show that this direct quantization at the facilitator results in asymmetric noise levels at the nodes, which in turn impacts the overall key-rate.Identifying the above issue, we propose a practical GSK generation protocol, referred to as Algebraic Symmetrically Quantized GSK (A-SQGSK) protocol, in a network of three nodes. In the proposed protocol, due to quantization of symbols at the facilitator, the other two nodes also quantize their channel realizations, and use them appropriately over algebraic rings to generate the keys. Under special conditions, we analytically show that the A-SQGSK protocol provides higher key-rate than the baselines, and also prove that the proposed protocol incurs zero leakage to an external eavesdropper. We also use extensive simulation results to demonstrate the benefits of the proposed protocol at different regimes of signal-to-noise-ratios.

Due to its prodigious advantages, smart grid technology has received considerable attention in recent years. However, security issues are still currently challenging in smart grid. In this paper, aiming at tackle the security issue of power consumption data, we propose a new Ciphertext Policy Attribute-based Encryption (CP-ABE) scheme with revocation for the fog- based smart grid system. Specifically, in order to achieve attribute revocation without requiring users to be always online, we divide users' attributes into attribute groups, assign an attribute group key to each group, and selectively distribute group key update messages. In addition, our scheme uses the DH (Diffie- Hellman) tree to distribute the group key statelessly, which solves the problem of collusion attack. The combination of attribute revocation and user revocation has been used to improve the efficiency of the revocation mechanism. Furthermore, the proposed scheme outsources unnecessary computing operations to fog nodes, so that the computing overhead of users is independent of the number of attributes. Both security analysis and experimental results demonstrate that our proposed scheme can balance the security objectives with the actual efficiency.

We advance the state-of-the-art in automated symbolic cryptographic protocol analysis by providing the first algorithm that can handle Diffie-Hellman exponentiation, bilinear pairing, and AC-operators. Our support for AC-operators enables protocol specifications to use multisets, natural numbers, and finite maps. We implement the algorithm in the Tamarin prover and provide the first symbolic correctness proofs for group key agreement protocols that use Diffie-Hellman or bilinear pairing, loops, and recursion, while at the same time supporting advanced security properties, such as perfect forward secrecy and eCK-security. We automatically verify a set of protocols, including the STR, group Joux, and GDH protocols, thereby demonstrating the effectiveness of our approach.

Vehicular ad hoc networks (VANETs) have been growing rapidly because it can improve traffic safety and efficiency in transportation. In VANETs, messages are broadcast in wireless environment, which is vulnerable to be attacked in many ways. Accordingly, it is essential to authenticate the legitimation of vehicles to guarantee the performance of services. In this paper, we propose an anonymous conditional privacy-preserving authentication scheme based on message authentication code (MAC) for VANETs. With verifiable secret sharing (VSS), vehicles can obtain a group key for message generation and authentication after a mutual authentication phase. Security analysis and performance evaluation show that the proposed scheme satisfies basic security and privacy-preserving requirements and has a better performance compared with some existing schemes in terms of computational cost and communication overhead.

In addition to the security and privacy challenges in vehicular ad hoc network (VANET), the computational and communicational costs are huge challenges, since they increase the network latency, thus casing to reduce the network's communication efficiency, providing to the attacker with an opportunity to penetrate the network. In this paper, we propose a new scheme to eliminate the mentioned challenges in VANET systems. In the first part of this scheme, we initialize and register the On-Board Units (OBUs) and Road Side Units (RSUs). In the second part, an exchange between the RSU and OBU of mutual authentication and group key generation via Chinese remainder theorem (CRT) as well as using the bloom filter (BF) in broadcasting and verifying beacons. Whereas in the third part, there are two major stages, the first stage occurred when the vehicle leaves the group, and the other stage if the trusted vehicle starts to broadcast bogus information. The proposed scheme overcomes state-of-the-art schemes in security, privacy, and communication and computational costs. Moreover, it provides a convenient low overhead for low latency.

To facilitate the successful deployments of the Internet of Things (IoT) applications, the support of secure and efficient communication protocol and architecture is inevitable. Owing to its lightweight and easiness, the Message Queue Telemetry Transport (MQTT) has become one of the most popular communication protocols in the Internet-of-Things (IoT). However, the security supports in the MQTT are very weak: it assumes the security support from the underlying Secure Sockets Layer (SSL). The weakness incurs several key drawbacks. One is the support of SSL capacities is a pressure for those resources-constrained devices. One another and very important one is the lack of the support of secure group communication. Without efficient and secure group communication support, the MQTT-based IoT systems would suffer from deteriorated computational and communication performance, especially when there are tons of IoT devices accessing the systems. In this paper, we design a secure MQTT group communication framework in which each MQTT application would periodically updates the group key and the data communication can be efficiently and securely encrypted by the group keys. Both our prototype system and the analysis show that our design can improve the performance of security, computation, and communication.

This paper focuses on the problem of low transfer efficiency and security privacy during the transfer of a large number of tags. The physical unclonable function, Rabin, XOR, random number and other encryption schemes are adopted to protect the security of low-cost tags. A group of tags and a group key scheme are adopted to speed up the tags’ ownership transfer time. Using the anonymous RFID system and some encryption schemes to protect the location privacy of tags and the problem of information privacy during transfer. The scheme of adding missing tags detection links and simple group coding is adopted to prevent attacks and reduce the search time of missing tags. And finally the GNY logic is adopted to prove the security and privacy of the ownership transfer agreement. The simulation results show that the ownership transfer time is reduced, the speed of ownership transfer is accelerated, and the efficiency of exchange is improved.

Establishing quick and secure communication between rescue team members in the disaster field is a significant task and wireless mesh network (WMN) is the best choice for disaster management and other emergency situations. This paper presents a BEhavior based Key Agreement (BEKA). First, BEKA presents an approach that not only takes the static nature of mesh routers and resource constraint of mesh clients into considerations, but also ensures that every active member contributes equally towards the group key. Second, BEKA adapts the stay duration behavior of mesh clients and proposes interval JoLe (Join/Leave) rekeying protocols to reduce the overhead of rekey operations upon highly frequent membership dynamics. Our analysis concludes that BEKA reduces the rekeying cost effectively and efficiently comparing with the tradition rekeying methods.

This paper is part of a research which the authors are carrying out for designing a secured transmission for IoT (Internet of Things). In this scenario group key plays a major role as vehicles would be grouped according to their size. A unique group key establishment system has been proposed where High Definition images(HDRI) are taken as a group key, the images are first watermarked using DWT and then encrypted and are assigned to each group. To access a device(source) of a group the key stored for the source is transmitted to the target trying to establish a connection. The target would be having the decryption algorithm where the image would be decrypted and the watermarked image is extracted and matched with the stored image, once a match is found the connection would be established between the source and the target but to access the device of the source target would again have to establish a simple device key authentication after which a complete connectivity would be possible. The proposed system is unique as there is no decryption key and uses images for authentication. It is the future of a secured IoT and networking as a whole. To check the robustness of the system various attacks including Man in the middle have been tried and quality of the extracted watermarked images has also been checked and it has been observed that the quality remains good even after transmitting the images in a linear form over the network.

The data-sharing in cloud computing will enable many users to share the data. This helps in accessing the information easily and to share the data efficiently. The healthcare data will have to be shared amongst different healthcare centers and the medical practitioners. This involves security issues while sharing the healthcare data within a group. We provide the group model for sharing of data that is based on block based design where the group members will perform the key agreement to get the common group key that helps to shares the data securely. The fault tolerant property is provided by this design which can detect the malicious attackers during the group data sharing. The proposed group data-sharing is compared with the existing data sharing models w.r.t. the time cost of computation for group key generation and sharing of data.

Physical-layer secret key generation (PSKG) leveraging reciprocal wireless channel has been widely studied in pairwise communication scenarios as it addresses the key distribution problem in traditional security mechanisms. However, PSKG encounters the challenges of low key agreement, information leakage and high system cost when it is extended to produce a secret key for a group of users. In this paper, we propose a lightweight Group secret key generation approach leveraging Non-reconciled received Signal Strength (GNSS). Specifically, pairwise bit sequences with high similarity are firstly extracted and then a group key is securely shared with the protection of these pairwise bit sequences, which prevents the information leakage and sophisticated information reconciliation. Detailed algorithms of GNSS for star and chain networks are presented. Numerical and experimental results demonstrate that GNSS can provide high key agreement, thus enabling key generation technology to be used in a group communication scenario.

Due to tremendous development in the network technologies forms an Internet of Things (IoT) based Health Care System (HCS) is an essential application in day-today life. In HCS, constitute a group communication among doctors, patient, caretaker, ambulance, and hospital, which intern's devices transfer personal information from one to many group members. Providing security on the personal health information is the most critical issue, because malicious access on this information may leads to life threads. Concurrently, traditional cryptographic framework has unsuccessful to protection to the HCS over lightweight communications network. So, the proposed framework deals the security flaws through hyper elliptic curve based public key cryptosystem, which combines Digital Signature algorithm, Elgamal approaches that ensure the entity authentication and secure group communication. The performance of the proposed work analyzed using efficient security measures and compared with related schemes.

Secure group communication in the Internet of Things (IoT) requires the establishment and management of one or more group keys to provide group security services such as confidentiality of group messages. One of the main challenges in ensuring secure group communication in IoT is designing a group key establishment scheme that is feasible for nodes with limited computational capabilities. In this paper, we propose a lightweight group key establishment scheme based on fast symmetric-key encryption. We show a mechanism for designing a lightweight and secure IoT group key establishment and management scheme whose security is underpinned by the perfect secrecy provided by the One Time Pad. We then argue that the scheme is convenient for IoT group applications where nodes are resource-constrained. We prove that our scheme is secure under a threat model where the attacker has sufficiently large computational power. We also prove that the scheme provides desired group security properties such as confidentiality, key secrecy and independent group session keys generation.

This paper presents a new key management protocol for group-based communications in non-hierarchical wireless sensor networks (WSNs), applied on a recently proposed IP-based multicast protocol. Confidentiality, integrity, and authentication are established, using solely symmetric-key-based operations. The protocol features a cloud-based network multicast manager (NMM), which can create, control, and authenticate groups in the WSN, but is not able to derive the actual constructed group key. Three main phases are distinguished in the protocol. First, in the registration phase, the motes register to the group by sending a request to the NMM. Second, the members of the group calculate the shared group key in the key construction phase. For this phase, two different methods are tested. In the unicast approach, the key material is sent to each member individually using unicast messages, and in the multicast approach, a combination of Lagrange interpolation and a multicast packet are used. Finally, in the multicast communication phase, these keys are used to send confidential and authenticated messages. To investigate the impact of the proposed mechanisms on the WSN, the protocol was implemented in ContikiOS and simulated using COOJA, considering different group sizes and multi-hop communication. These simulations show that the multicast approach compared to the unicast approach results in significant smaller delays, is a bit more energy efficient, and requires more or less the same amount of memory for the code.

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 agreement protocols for secure 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., info:eu-repo/semantics/published

Designing fast and secure RFID private authentication with structured key management is one of the most essential components for RFID-enabled large-scale object management. Since group keys are shared by some tags in structured key-based authentication, physical tampering of tags, so called the compromise attack, may enable the adversary to obtain group keys stored in the compromised tags, which in turn can be used to distinguish other tags. All existing structured key-based protocols try to reduce the common group key effect to preserve high privacy. However, the theoretical bound of weak privacy achievable by structured key-based authentication remains unknown. In this paper, we investigate weak privacy in RFID authentication. To this end, we first formulate a mathematical model which identifies the probability of two tags being linked with respect to the number of group keys. Our model shows that the existing solutions are far from the ultimate goal in weak privacy. Then, we propose a k-neighbor graph-based RFID authentication (KNGA) protocol, where random walk over a k-neighbor graph is performed. In addition, we show that KNGA achieves the performance bound, and we then quantify the degree of privacy by anonymity. Finally, the extensive simulations demonstrate that the proposed protocol successfully achieves its design goals.

In recent years, there has been a growth in Internet of Things (IoT) technologies that are used to collect and exchange data. In such networks, devices communicate with each other to collect data. It is important for IoT networks to communicate securely and this requires efficient key sharing. Pairwise keys, group keys, and broadcast keys are used in IoT networks. Hamasaki and others proposed a geometric method for group key sharing. The method can be easily used for broadcast key sharing. However, the method incurs considerable computation cost because of the large number of devices in the network. Therefore, we propose an efficient method based on the geometric method for pairwise key sharing and compare our proposed method with other schemes.

Machine Type Communication (MTC) is one among the fastest emerging technologies of mobile communication due to the massive increase in number of Network of things devices. The Third Generation Partnership Project (3GPP) has considered MTC as a part of Long Term Evolution (LTE) infrastructure in order to support various MTC applications. In order to communicate with the MTC server, an MTC device (MTCD) must authenticate to the network. The LTE network nodes suffers from signaling congestion when multiple MTCDs tries to authenticate to the network simultaneously. To overcome signaling congestion, several protocols have been proposed but the existing protocols use the concept of sharing of group key for authentication. We propose HGKA protocol to enhances the security compared to the existing schemes by avoiding the sharing or pre-storing of the group key to achieve group authentication. The proposed protocol employs authenticated group key agreement which can be used for group authentication and also provides forward secrecy and backward secrecy when an MTCD member gets added or leaves from the group by updating the group key.

A group key management scheme is for a group controller to manage an encryption key for a collection of users to communicate messages among themselves securely. The presence of group key with each node is de-facto that holds the group together. A dynamic group key management scheme is considered secure if it can preserve both backward and forward secrecy. With this as objective, a wide variety of group key management schemes were proposed. However, we highlight that these schemes provide security only under passive attack model and are completely defenceless against an active outsider adversary. Hence, to press over our point, in this paper, we have selected four categories of group key management schemes and analyze one base scheme from each of these categories under active outsider attack model. We point to the fact that all of them are insecure under active outsider attack model and comprehensively reason for their insecurity. The only way these schemes can be secured is by re-instantiating the group again.

Dynamic group key agreement protocols are cryptographic primitives to provide secure group communications in decentralized and dynamic networks. Such protocols provide additional operations to update the group key while adding new participants into the gr Dept. of Computer Engineering, Bogazici University, Istanbul, 34342, Turkey; Dept. of Computer Engineering, Bogazici University, EURECOM Biot, Sophia-Antipolis, 06410, France; Dept. of Computer Engineering, Yasar University, Izmir, 35100, Turkey

Recently, privacy emerged as a hot issue again, as the General Data Protection Regulation (GDPR) of EU has become enforceable since May 25, 2018. This paper deals with the problem of health information sharing on a website securely and with preserving privacy. In the context of patient networks (such as ‘PatientsLikeMe’ or ‘CureTogether’), we propose the model Secure Information Sharing System (SISS) with the main method of group key cryptosystem. SISS addresses important problems of group key systems. (1) The new developed equations for encryption and decryption can eliminate the rekeying and redistribution process for every membership-change of the group, keeping the security requirements. (2) The new 3D Stereoscopic Image Mobile Security Technology with AR (augmented reality) solves the problem of conspiracy by group members. (3) SISS uses the reversed one-way hash chain to guarantee forward secrecy and backward accessibility (security requirements for information sharing in a group). We conduct a security analysis of SISS according to group information sharing secrecy and an experiment on its performance. Consequently, although current IT paradigm is changing to be more and more ‘complicated’, ‘overlapped’, and ‘virtualized’, SISS makes it possible to securely share sensitive information from collaborative work.

Group key agreement is one of the key technologies for ensuring information exchange security among group members. It is widely used in secure multiparty computation, resource security sharing, and distributed collaborative computing et al. The current group key agreement requires personal privacy protection, lightweight computing and more efficient and secure group key agreement technology. Aiming at these requirements, this paper proposed a lightweight group key agreement protocol based on blockchain, which uses the technical advantages of blockchain and asymmetric group key agreement combined. In this protocol, the blockchain anonymous authentication technology is used to implement personal privacy protection in the identity authentication process of the group key agreement, and the blockchain decentralized computing technology is adopted to reduce the computational and communication overhead of each participant. So it also suite able to use in resource-constrained mobile network, It also uses blockchain recording techniques for traceability and accountability (if some participants impersonate or falsify data, they can be recorded by the blockchain. No malicious attempts can be made undetected). This protocol is proved secure under the decisional bilinear Diffie-Hellman (DBDH) problem assumption and the performance analysis shows that the proposed scheme is more efficient than existing works.

Safeguarding privacy of ratings assigned by users is an important issue for recommender systems. There are several existing protocols that allow a server to generate recommendations from homomorphically encrypted ratings, thereby ensuring privacy of rating data. After collecting the encrypted ratings, the server may require further interaction with each user, which is problematic in case some users were to go offline. To solve the offline user problem previous solutions use additional semi-honest third parties. In this paper, we propose a privacy-preserving recommender system that does not suffer from the offline user problem. Unlike previous works, our proposal does not require any additional third party. We demonstrate with the help of experiments that the time required to generate recommendations is efficient for practical applications.

In recent years, Multi-Processor System-on-Chips (MPSoCs) are widely deployed in safety-critical embedded systems. The Cloud-of-Chips (CoC) is a scalable MPSoC architecture comprised of a large number of interconnected Integrated Circuits (IC) and Processing Clusters (PC) destined for critical systems. While many researches have focused on addressing the hardware issues of MPSoCs, the communication over them has not been very well explored. Following the SDN concept, we propose a new protocol in order to secure the communication and efficiently manage the routing within the CoC. The SSPSoC includes a private key derivation phase, a group key agreement (GKA) phase, and a data exchange phase in order to ensure that basic security primitives are preserved and provide secure communication. Furthermore, a network of 1-30 nodes is set in order to validate the proposed protocol and measure the network performance and memory consumption of the proposed protocol., SCOPUS: ar.j, info:eu-repo/semantics/published

Vehicular ad-hoc networks (VANETs) have got a wide range of attention to improve traffic systems and smart cities. Security and privacy are critical issues and need to be addressed for effective VANET systems. In this paper, we propose an efficient conditional privacy-Preserving authentication scheme based on a group secret key. Many VANETs schemes have utilized a group signature to realize the identity-less authentication, but the existing schemes suffering from long and high computational procedures, especially in the Certificate Revocation List (CRL) verification process, and group management complexity issues. As a result, they cannot satisfy the VANETs efficiency requirements. On another hand, many pseudonym-ID based VANETs schemes utilized a system key signature, but those schemes suffering from communication overhead increasing which could be caused by the increasing of the revocation list, in addition to that, and any damage in the key will cause damage for the entire system. In our scheme, we use a permanent vehicle pseudonym-ID and temporary group secret key that offers a lightweight verification and authentication process for a secure and efficient VANET system.

This paper addresses the issue in managing a group key among dynamic group of nodes in mobile ad hoc networks (MANETs), where the participants frequently miss the group key update, commonly known as rekeying. In this paper, we propose a broadcast stateless and distributed group key management (GKM) framework: genetic-based Bayesian networks group key agreement (GBKA) scheme, for supporting dynamic rekeying mechanism in MANET. The proposed framework includes two main functionalities: First to initialize the construction of group key and second is to optimize the keys to maintain the group communication with less overhead, whenever membership changes. The genetic algorithm selects individuals with high genetic characteristics that reflect the node’s ability to adapt and survive the MANET environments. The rekeying scheme operates on genetic computation over finite area with Bayesian network modelling. Whenever the group membership changes, the public messages are updated accordingly with an unchanged private key. Our proposed scheme is very efficient with hash and Lagrange interpolation polynomial implementation. The simulation results show that the proposed group key management scheme achieved higher performance and security compared with other existing key management schemes.

For 5G based Vehicle-to-Everything (V2X) communications, it is envisioned that the network latency will be dramatically decreased to the extent of 1msec. However, achieving such low latency with high mobility in vehicular networks is a challenge. In this paper, we propose a lightweight group authentication scheme for 5G- based V2X communications using three different vehicles' roles in each cluster: an ordinary vehicle, Cluster Head (CH), and gateway vehicle. To increase cluster connectivity time, our clustering algorithm is developed based on three metrics: cluster's relative velocity, relative position, and received signal strength. The proposed authentication scheme aims to mutually authenticate the vehicle and CH as well as create a shared group key to be used inside the cluster. The security analysis and performance evaluation show that our proposed scheme thwarts inside and outside authentication attacks, and achieves up to 50% less computation overhead than those achieved in the existing schemes.

Over the years, email has evolved into one of the most widely used communication channels for both individuals and organizations. However, despite near ubiquitous use in much of the world, current information technology standards do not place emphasis on email security. Not until recently, webmail services such as Yahoo's mail and Google's gmail started to encrypt emails for privacy protection. However, the encrypted emails will be decrypted and stored in the service provider's servers. If the servers are malicious or compromised, all the stored emails can be read, copied and altered. Thus, there is a strong need for end-to-end (E2E) email encryption to protect email user's privacy. In this paper, we present a certificateless one-way group key agreement protocol with the following features, which are suitable to implement E2E email encryption: (1) certificateless and thus there is no key escrow problem and no public key certificate infrastructure is required; (2) one-way group key agreement and thus no back-and-forth message exchange is required; and (3) n-party group key agreement (not just 2- or 3-party). This paper also provides a security proof for the proposed protocol using "proof by simulation". Finally, efficiency analysis of the protocol is presented at the end of the paper.

5G wireless together with optical backbone networks are expected to be the main pillars of the envisaged next /future generation networking (N/FGN) infrastructures. This is an impetus to practical realization of an IoT network that will support and ensure relatively higher bandwidth as well as enhanced quality of service (QoS) in both access and core network sections. The high-speed wireless links at the network peripherals will serve as a conducive platform for device-to-device (D2D) communication. D2D driven applications and services can only be effective as well as secure assuming the associated machine type communication devices (MTCDs) have been successfully verified and authenticated. Typically, D2D type services and applications involve the interaction of several MTCDs in a group. As such, secure and effective D2D group-based authentication and key agreement (AKA) protocols are necessary. They need to inherently achieve efficacy in maintaining the group key unlink-ability as well as generate minimal signalling overheads that otherwise may lead to network congestion. In this paper we detail a secure and efficient Group AKA (Gr-AKA) protocol for D2D communication. Its performance is compared to that of existing similar protocols and is found to comparably lower both computational as well as signalling overhead requirements. Overall the analysis shows that the Gr-AKA protocol improves performance in terms of fulfilling D2D communication’s security requirements.