Biblio

The average computer user is no longer restricted to one device. They may have several devices and expect their applications to work on all of them. A challenge arises when these applications need the cryptographic private key of the devices' owner. Here the device owner typically has to manage keys manually with a "keychain" app, which leads to private keys being transferred insecurely between devices – or even to other people. Even with intuitive synchronization mechanisms, theft and malware still pose a major risk to keys. Phones and watches are frequently removed or set down, and a single compromised device leads to the loss of the owner's private key, a catastrophic failure that can be quite difficult to recover from. We introduce Shatter, an open-source framework that runs on desktops, Android, and Android Wear, and performs key distribution on a user's behalf. Shatter uses threshold cryptography to turn the security weakness of having multiple devices into a strength. Apps that delegate cryptographic operations to Shatter have their keys compromised only when a threshold number of devices are compromised by the same attacker. We demonstrate how our framework operates with two popular Android apps (protecting identity keys for a messaging app, and encryption keys for a note-taking app) in a backwards-compatible manner: only Shatter users need to move to a Shatter-aware version of the app. Shatter has minimal impact on app performance, with signatures and decryption being calculated in 0.5s and security proofs in 14s.

Video surveillance has been widely adopted to ensure home security in recent years. Most video encoding standards such as H.264 and MPEG-4 compress the temporal redundancy in a video stream using difference coding, which only encodes the residual image between a frame and its reference frame. Difference coding can efficiently compress a video stream, but it causes side-channel information leakage even though the video stream is encrypted, as reported in this paper. Particularly, we observe that the traffic patterns of an encrypted video stream are different when a user conducts different basic activities of daily living, which must be kept private from third parties as obliged by HIPAA regulations. We also observe that by exploiting this side-channel information leakage, attackers can readily infer a user's basic activities of daily living based on only the traffic size data of an encrypted video stream. We validate such an attack using two off-the-shelf cameras, and the results indicate that the user's basic activities of daily living can be recognized with a high accuracy.

In order to provide secure data communication in present cyber space world, a stronger encryption technique becomes a necessity that can help people to protect their sensitive information from cryptanalyst. This paper proposes a novel symmetric block cipher algorithm that uses multiple access circular queues (MACQs) of variable lengths for diffusion of information to a greater extent. The keys are randomly generated and will be of variable lengths depending upon the size of each MACQ.A number of iterations of circular rotations, swapping of elements and XORing the key with queue elements are performed on each MACQ. S-box is used so that the relationship between the key and the cipher text remains indeterminate or obscure. These operations together will help in transforming the cipher into a much more complex and secure block cipher. This paper attempt to propose an encryption algorithm that is secure and fast.

Lightweight block ciphers, which are required for IoT devices, have attracted attention. Simeck, which is one of the most popular lightweight block ciphers, can be implemented on IoT devices in the smallest area. Regarding the hardware security, the threat of electromagnetic analysis has been reported. However, electromagnetic analysis of Simeck has not been reported. Therefore, this study proposes a dedicated electromagnetic analysis for a lightweight block cipher Simeck to ensure the safety of IoT devices in the future. To our knowledge, this is the first electromagnetic analysis for Simeck. Experiments using a FPGA prove the validity of the proposed method.

This paper presents a possible solution to a fundamental limitation facing all blockchain-based systems; scalability. We propose a temporal rolling blockchain which solves the problem of its current exponential growth, instead replacing it with a constant fixed-size blockchain. We conduct a thorough analysis of related work and present a formal analysis of the new rolling blockchain, comparing the results to a traditional blockchain model to demonstrate that the deletion of data from the blockchain does not impact on the security of the proposed blockchain model before concluding our work and presenting future work to be conducted.

Tensors are a multi-linear generalization of matrices to their d-way counterparts, and are receiving intense interest recently due to their natural representation of high-dimensional data and the availability of fast tensor decomposition algorithms. Given the input-output data of a nonlinear system/circuit, this paper presents a nonlinear model identification and simulation framework built on top of Volterra series and its seamless integration with tensor arithmetic. By exploiting partially-symmetric polyadic decompositions of sparse Toeplitz tensors, the proposed framework permits a pleasantly scalable way to incorporate high-order Volterra kernels. Such an approach largely eludes the curse of dimensionality and allows computationally fast modeling and simulation beyond weakly nonlinear systems. The black-box nature of the model also hides structural information of the system/circuit and encapsulates it in terms of compact tensors. Numerical examples are given to verify the efficacy, efficiency and generality of this tensor-based modeling and simulation framework.

Cloud platforms can leverage Trusted Platform Modules to help provide assurance to clients that cloud-based Web services are trustworthy and behave as expected. We discuss a variety of approaches to providing this assurance, and we implement one approach based on the concept of a trustworthy certificate authority. TaoCA, our prototype implementation, links cryptographic attestations from a cloud platform, including a Trusted Platform Module, with existing TLS-based authentication mechanisms. TaoCA is designed to enable certificate authorities, browser vendors, system administrators, and end users to define and enforce a range of trust policies for web services. Evaluation of the prototype implementation demonstrates the feasibility of the design, illustrates performance tradeoffs, and serves as an end-to-end, proof-of-concept evaluation of underlying trustworthy computing abstractions. The proposed approach can be deployed incrementally and provides new benefits while retaining compatibility with the existing public key infrastructure used for TLS. 

Currently, different forms of ransomware are increasingly threatening Internet users. Modern ransomware encrypts important user data, and it is only possible to recover it once a ransom has been paid. In this article we show how software-defined networking can be utilized to improve ransomware mitigation. In more detail, we analyze the behavior of popular ransomware - CryptoWall - and, based on this knowledge, propose two real-time mitigation methods. Then we describe the design of an SDN-based system, implemented using OpenFlow, that facilitates a timely reaction to this threat, and is a crucial factor in the case of crypto ransomware. What is important is that such a design does not significantly affect overall network performance. Experimental results confirm that the proposed approach is feasible and efficient.

Among the current Wi-Fi two security models (Enterprise and Personal), while the Enterprise model (802.1X) offers an effective framework for authenticating and controlling the user traffic to a protected network, the Personal model (802.11) offers the cheapest and the easiest to setup solution. However, the drawback of the personal model implementation is that all access points and client radio NIC on the wireless LAN should use the same encryption key. A major underlying problem of the 802.11 standard is that the pre-shared keys are cumbersome to change. So if those keys are not updated frequently, unauthorized users with some resources and within a short timeframe can crack the key and breach the network security. The purpose of this paper is to propose and implement an effective method for the system administrator to manage the users connected to a router, update the keys and further distribute them for the trusted clients using the Freescale embedded system, Infrared and Bluetooth modules.

In this paper a novel set-theoretic control framework for Cyber-Physical Systems is presented. By resorting to set-theoretic ideas, an anomaly detector module and a control remediation strategy are formally derived with the aim to contrast cyber False Data Injection (FDI) attacks affecting the communication channels. The resulting scheme ensures Uniformly Ultimate Boundedness and constraints fulfillment regardless of any admissible attack scenario.

Attacks of Ransomware are increasing, this form of malware bypasses many technical solutions by leveraging social engineering methods. This means established methods of perimeter defence need to be supplemented with additional systems. Honeypots are bogus computer resources deployed by network administrators to act as decoy computers and detect any illicit access. This study investigated whether a honeypot folder could be created and monitored for changes. The investigations determined a suitable method to detect changes to this area. This research investigated methods to implement a honeypot to detect ransomware activity, and selected two options, the File Screening service of the Microsoft File Server Resource Manager feature and EventSentry to manipulate the Windows Security logs. The research developed a staged response to attacks to the system along with thresholds when there were triggered. The research ascertained that witness tripwire files offer limited value as there is no way to influence the malware to access the area containing the monitored files.

Notions like security, trust, and privacy are crucial in the digital environment and in the future, with the advent of technologies like the Internet of Things (IoT) and Cyber-Physical Systems (CPS), their importance is only going to increase. Trust has different definitions, some situations rely on real-world relationships between entities while others depend on robust technologies to gain trust after deployment. In this paper we focus on these robust technologies, their evolution in past decades and their scope in the near future. The evolution of robust trust technologies has involved diverse approaches, as a consequence trust is defined, understood and ascertained differently across heterogeneous domains and technologies. In this paper we look at digital trust technologies from the point of view of security and examine how they are making secure computing an attainable reality. The paper also revisits and analyses the Trusted Platform Module (TPM), Secure Elements (SE), Hypervisors and Virtualisation, Intel TXT, Trusted Execution Environments (TEE) like GlobalPlatform TEE, Intel SGX, along with Host Card Emulation, and Encrypted Execution Environment (E3). In our analysis we focus on these technologies and their application to the emerging domains of the IoT and CPS.

With increasing popularity of cloud computing, the data owners are motivated to outsource their sensitive data to cloud servers for flexibility and reduced cost in data management. However, privacy is a big concern for outsourcing data to the cloud. The data owners typically encrypt documents before outsourcing for privacy-preserving. As the volume of data is increasing at a dramatic rate, it is essential to develop an efficient and reliable ciphertext search techniques, so that data owners can easily access and update cloud data. In this paper, we propose a privacy preserving multi-keyword ranked search scheme over encrypted data in cloud along with data integrity using a new authenticated data structure MIR-tree. The MIR-tree based index with including the combination of widely used vector space model and TF×IDF model in the index construction and query generation. We use inverted file index for storing word-digest, which provides efficient and fast relevance between the query and cloud data. Design an authentication set(AS) for authenticating the queries, for verifying top-k search results. Because of tree based index, our scheme achieves optimal search efficiency and reduces communication overhead for verifying the search results. The analysis shows security and efficiency of our scheme.

In this paper, we propose a new color image encryption and compression algorithm based on the DNA complementary rule and the Chinese remainder theorem, which combines the DNA complementary rule with quantum chaotic map. We use quantum chaotic map and DNA complementary rule to shuffle the color image and obtain the shuffled image, then Chinese remainder theorem from number theory is utilized to diffuse and compress the shuffled image simultaneously. The security analysis and experiment results show that the proposed encryption algorithm has large key space and good encryption result, it also can resist against common attacks.

In recent years, more and more multimedia data are generated and transmitted in various fields. So, many encryption methods for multimedia content have been put forward to satisfy various applications. However, there are still some open issues. Each encryption method has its advantages and drawbacks. Our main goal is expected to provide a solution for multimedia encryption which satisfies the target application constraints and performs metrics of the encryption algorithm. The Advanced Encryption Standard (AES) is the most popular algorithm used in symmetric key cryptography. Furthermore, chaotic encryption is a new research direction of cryptography which is characterized by high initial-value sensitivity and good randomness. In this paper we propose a hybrid video cryptosystem which combines two encryption techniques. The proposed cryptosystem realizes the video encryption through the chaos and AES in CTR mode. Experimental results and security analysis demonstrate that this cryptosystem is highly efficient and a robust system for video encryption.

We propose a multi-level CSI quantization and key reconciliation scheme for physical layer security. The noisy wireless channel estimates obtained by the users first run through a transformation, prior to the quantization step. This enables the definition of guard bands around the quantization boundaries, tailored for a specific efficiency and not compromising the uniformity required at the output of the quantizer. Our construction results in an better key disagreement and initial key generation rate trade-off when compared to other level-crossing quantization methods.

We ask whether it is possible to anonymously communicate a large amount of data using only public (non-anonymous) communication together with a small anonymous channel. We think this is a central question in the theory of anonymous communication and to the best of our knowledge this is the first formal study in this direction. Towards this goal, we introduce the novel concept of anonymous steganography: think of a leaker Lea who wants to leak a large document to Joe the journalist. Using anonymous steganography Lea can embed this document in innocent looking communication on some popular website (such as cat videos on YouTube or funny memes on 9GAG). Then Lea provides Joe with a short decoding key dk which, when applied to the entire website, recovers the document while hiding the identity of Lea among the large number of users of the website. Our contributions include: Introducing and formally defining anonymous steganography, A construction showing that anonymous steganography is possible (which uses recent results in circuits obfuscation), A lower bound on the number of bits which are needed to bootstrap anonymous communication.

With the ever increasing growth of internet usage, ensuring high security for information has gained great importance, due to the several threats in the communication channels. Hence there is continuous research towards finding a suitable approach to ensure high security for the information. In recent decades, cryptography is being used extensively for providing security on the Internet although primarily used in the military and diplomatic communities. One such approach is the application of Chaos theory in cryptosystems. In this work, we have proposed the usage of combined multiple recursive generator (CMRG) for KEY generation based on a chaotic function to generate different multiple keys. It is seen that negligible difference in parameters of chaotic function generates completely different keys as well as cipher text. The main motive for developing the chaos based cryptosystem is to attain encryption that provides high security at comparatively higher speed but with lower complexity and cost over the conventional encryption algorithms.

In this paper, we present a new secure message transmission scheme using hyperchaotic discrete primary and auxiliary chaotic systems. The novelty lies on the use of auxiliary chaotic systems for the encryption purposes. We have used the modified Henon hyperchaotic discrete-time system. The use of the auxiliary system allows generating the same keystream in the transmitter and receiver side and the initial conditions in the auxiliary systems combined with other transmitter parameters suffice the role of the key. The use of auxiliary systems will mean that the information of keystream used in the encryption function will not be present on the transmitted signal available to the intruders, hence the reconstructing of the keystream will not be possible. The encrypted message is added on to the dynamics of the transmitter using inclusion technique and the dynamical left inversion technique is employed to retrieve the unknown message. The simulation results confirm the robustness of the method used and some comments are made about the key space from the cryptographic viewpoint.

Bitcoin, a decentralized cryptographic currency that has experienced proliferating popularity over the past few years, is the common denominator in a wide variety of cybercrime. We perform a measurement analysis of CryptoLocker, a family of ransomware that encrypts a victim's files until a ransom is paid, within the Bitcoin ecosystem from September 5, 2013 through January 31, 2014. Using information collected from online fora, such as reddit and BitcoinTalk, as an initial starting point, we generate a cluster of 968 Bitcoin addresses belonging to CryptoLocker. We provide a lower bound for CryptoLocker's economy in Bitcoin and identify 795 ransom payments totalling 1,128.40 BTC (\$310,472.38), but show that the proceeds could have been worth upwards of \$1.1 million at peak valuation. By analyzing ransom payment timestamps both longitudinally across CryptoLocker's operating period and transversely across times of day, we detect changes in distributions and form conjectures on CryptoLocker that corroborate information from previous efforts. Additionally, we construct a network topology to detail CryptoLocker's financial infrastructure and obtain auxiliary information on the CryptoLocker operation. Most notably, we find evidence that suggests connections to popular Bitcoin services, such as Bitcoin Fog and BTC-e, and subtle links to other cybercrimes surrounding Bitcoin, such as the Sheep Marketplace scam of 2013. We use our study to underscore the value of measurement analyses and threat intelligence in understanding the erratic cybercrime landscape.

Suppose that you have n truly random bits x=(x1,…,xn) and you wish to use them to generate m≫ n pseudorandom bits y=(y1,…, ym) using a local mapping, i.e., each yi should depend on at most d=O(1) bits of x. In the polynomial regime of m=ns, stextgreater1, the only known solution, originates from (Goldreich, ECCC 2000), is based on Random Local Functions: Compute yi by applying some fixed (public) d-ary predicate P to a random (public) tuple of distinct inputs (xi1,…,xid). Our goal in this paper is to understand, for any value of s, how the pseudorandomness of the resulting sequence depends on the choice of the underlying predicate. We derive the following results: (1) We show that pseudorandomness against F2-linear adversaries (i.e., the distribution y has low-bias) is achieved if the predicate is (a) k=Ω(s)-resilience, i.e., uncorrelated with any k-subset of its inputs, and (b) has algebraic degree of Ω(s) even after fixing Ω(s) of its inputs. We also show that these requirements are necessary, and so they form a tight characterization (up to constants) of security against linear attacks. Our positive result shows that a d-local low-bias generator can have output length of nΩ(d), answering an open question of Mossel, Shpilka and Trevisan (FOCS, 2003). Our negative result shows that a candidate for pseudorandom generator proposed by the first author (computational complexity, 2015) and by O’Donnell and Witmer (CCC 2014) is insecure. We use similar techniques to refute a conjecture of Feldman, Perkins and Vempala (STOC 2015) regarding the hardness of planted constraint satisfaction problems. (2) Motivated by the cryptanalysis literature, we consider security against algebraic attacks. We provide the first theoretical treatment of such attacks by formalizing a general notion of algebraic inversion and distinguishing attacks based on the Polynomial Calculus proof system. We show that algebraic attacks succeed if and only if there exist a degree e=O(s) non-zero polynomial Q whose roots cover the roots of P or cover the roots of P’s complement. As a corollary, we obtain the first example of a predicate P for which the generated sequence y passes all linear tests but fails to pass some polynomial-time computable test, answering an open question posed by the first author (Question 4.9, computational complexity 2015).

Media streaming has largely dominated the Internet traffic and the trend will keep increasing in the next years. To efficiently distribute the media content, Information-Centric Networking (ICN) has attracted many researchers. Since end users usually obtain content from indeterminate caches in ICN, the publisher cannot reinforce data security and access control depending on the caches. Hence, the ability of self-contained protection is important for the cached contents. Attribute-based encryption (ABE) is considered the preferred solution to achieve this goal. However, the existing ABE schemes usually have problems regarding efficiency. The exponentiation in key generation and pairing operation in decryption respectively increases linearly with the number of attributes involved, which make it costly. In this paper, we propose an efficient key-policy ABE with fast key generation and decryption (FKP-ABE). In the key generation, we get rid of exponentiation and only require multiplications/divisions for each attribute in the access policy. And in the decryption, we reduce the pairing operations to a constant number, no matter how many attributes are used. The efficiency analysis indicates that our scheme has better performance than the existing KP-ABE schemes. Finally, we present an implementation framework that incorporates the proposed FKP-ABE with the ICN architecture.

After a brief introduction on optical chaotic cryptography, we compare the standard short cavity, close-loop, two-laser and three-laser schemes for secure transmission, showing that both are suitable for secure data exchange, the three-laser scheme offering a slightly better level of privacy, due to its symmetrical topology.

When customers purchase a product or sign up for service from a company, they often are required to agree to a Privacy Policy or Terms of Service agreement. Many of these policies are lengthy, and a typical customer agrees to them without reading them carefully if at all. To address this problem, we have developed a prototype automatic text summarization system which is specifically designed for privacy policies. Our system generates a summary of a policy statement by identifying important sentences from the statement, categorizing these sentences by which of 5 "statement categories" the sentence addresses, and displaying to a user a list of the sentences which match each category. Our system incorporates keywords identified by a human domain expert and rules that were obtained by machine learning, and they are combined in an ensemble architecture. We have tested our system on a sample corpus of privacy statements, and preliminary results are promising.

This paper proposes a new hybrid technique for combined encryption text and image based on hyperchaos system. Since antiquity, man has continued looking for ways to send messages to his correspondents in order to communicate with them safely. It needed, through successive epochs, both physical and intellectual efforts in order to find an effective and appropriate communication technique. On another note, there is a behavior between the rigid regularity and randomness. This behavior is called chaos. In fact, it is a new field of investigation that is opened along with a new understanding of the frequently misunderstood long effects. The chaotic cryptography is thus born by inclusion of chaos in encryption algorithms. This article is in this particular context. Its objective is to create and implement an encryption algorithm based on a hyperchaotic system. This algorithm is composed of four methods: two for encrypting images and two for encrypting texts. The user chose the type of the input of the encryption (image or text) and as well as of the output. This new algorithm is considered a renovation in the science of cryptology, with the hybrid methods. This research opened a new features.