Vehicular Ad hoc NETworks (VANETs) serve as the backbone of Intelligent Transportation Systems (ITS), providing passengers with safety and comfort. However, VANETs are vulnerable to major threats that affect data privacy and network services either from an individual or distributed attacker. In this paper, a Secure and Private-Collaborative Intrusion Detection System (SP-CIDS) is proposed to detect network attacks and to mitigate security concerns. In SP-CIDS, a Distributed Machine Learning (DML) model based on the Alternating Direction Method of Multipliers (ADMM) is used, which leverages the potential of vehicle-to-vehicle collaboration in the learning process to improve the storage efficiency, accuracy, and scalability of the IDS. However, there are significant data privacy concerns possible in such collaboration, where a CIDS can act as a malicious system that has access to the intermediate stages of the learning process. Additionally, the SP-CIDS system uses Differential Privacy (DP) technique to address the aforementioned data privacy risk associated with the DML-based CIDS. The SP-CIDS system is evaluated with logistic regression, naïve bayes, and ensemble classifiers. Simulation results substantiate that a private ensemble classifier secures the training data with DP and also achieves 96.94% accuracy.

In this paper, we address the problems of key generation and management for enabling one-key-for-one-file secure encryption, where every file is encrypted by using an independent random key, which is highly desired in long-term protection of data stored on public clouds and other applications. A new concept dubbed information-theoretical ϵ-security is introduced to measure the security of a keystore (i.e., a set of random keys, ki, 1 ≤ i ≤ Λ, each consisting of l bits) which are generated from a random string of L bits, called the keystore seed. An efficient keystore generation scheme is presented, and the resulting keystore Ψ = {ki:1 ≤ i ≤ Λ} is shown to be information-theoretically e-secure with small e. Specifically, they satisfy the following properties: (1) Λ ≫ L is sufficiently large to realize one-key-for-one-file encryption for applications with a large number of files; (2) for any key index i, the key kiis uniformly distributed over the key space {0,1}1and hence statistically independent of i if i is chosen randomly; (3) for any two independent i, j, 1 ≤ i, j ≤ Λ, the probability that ki = kj is less than (1 - ϵ) × 2-l+ ϵ and (4) for any two independent key indices i and j, knowing i, j, and ki does not reduce the amount of uncertainty about kj significantly, i.e., the conditional Shannon entropy H (kj |i, j, ki)is at least as large as (1 - ϵ)H(kj | j). These security properties along with easy generation of each key ki from the keystore seed and the key index i remove most challenges in distributing and managing a large number of random keys.

In this paper, a suite of lightweight security protocols for the Internet of Things (IoT) is presented. It comprises protocols for lightweight encryption, authentication as well as key management. The key management protocol is the application of our early work on information theoretically secure key management to IoT; it is computationally efficient and information-theoretically secure, and enables that every data item (file) is encrypted with its own random key. The security and computational efficiency of the proposed protocols are compared with those of IPsec, which is the most commonly used suite of network-layer security protocols in Internet based applications but not desirable, due to its computationally-intensive procedures, to IoT applications and cyber-physical systems (CPS) with resource and computation-capability constraints. The proposed security protocols can be employed in IoT and CPS applications, replacing the IPsec core algorithms or the whole IPsec suite, to achieve a higher level of security with a very low resource consumption that helps to maintain the system sustainability.

Permutation is a commonly used primitive in multimedia (image/video) encryption schemes, and many permutation-only algorithms have been proposed in recent years for the protection of multimedia data. In permutation-only image ciphers, the entries of the image matrix are scrambled using a permutation mapping matrix which is built by a pseudo-random number generator. The literature on the cryptanalysis of image ciphers indicates that the permutation-only image ciphers are insecure against ciphertext-only attacks and/or known/chosenplaintext attacks. However, the previous studies have not been able to ensure the correct retrieval of the complete plaintext elements. In this paper, we revisited the previous works on cryptanalysis of permutation-only image encryption schemes and made the cryptanalysis work on chosen-plaintext attacks complete and more efficient. We proved that in all permutationonly image ciphers, regardless of the cipher structure, the correct permutation mapping is recovered completely by a chosenplaintext attack. To the best of our knowledge, for the first time, this paper gives a chosen-plaintext attack that completely determines the correct plaintext elements using a deterministic method. When the plain-images are of size M × N and with L different color intensities, the number n of required chosen plain-images to break the permutation-only image encryption algorithm is n = ΓlogL(MN)1. The complexity of the proposed attack is O (n · M N) which indicates its feasibility in a polynomial amount of computation time. To validate the performance of the proposed chosen-plaintext attack, numerous experiments were performed on two recently proposed permutation-only image/video ciphers. Both theoretical and experimental results showed that the proposed attack outperforms the state-of-theart cryptanalytic methods.

Due to widespread applications of 3D vision technology, the research into 3D object protection is primarily important. To maintain confidentiality, encryption of 3D objects is essential. However, the requirements and limitations imposed by 3D objects indicate the impropriety of conventional cryptosystems for 3D object encryption. This suggests the necessity of designing new ciphers. In addition, the study of prior works indicates that the majority of problems encountered with encrypting 3D objects are about point cloud protection, dimensional and spatial stability, and robustness against surface reconstruction attacks. To address these problems, this paper proposes a 3D object encryption scheme, based on a series of random permutations and rotations, which deform the geometry of the point cloud. Since the inverse of a permutation and a rotation matrix is its transpose, the decryption implementation is very efficient. Our statistical analyses show that within the cipher point cloud, points are randomly distributed. Furthermore, the proposed cipher leaks no information regarding the geometric structure of the plain point cloud, and is also highly sensitive to the changes of the plaintext and secret key. The theoretical and experimental analyses demonstrate the security, effectiveness, and robustness of the proposed cipher against surface reconstruction attacks.

By using the value assignment of Chen and Kløve we present new results on the pseudocodeword redundancy of binary linear codes. In particular, we give some upper bounds on the pseudoredundancies of certain codes with repeated coordinates and of certain shortened subcodes. We also investigate several kinds of k-dimensional binary codes and compute their exact pseudocodeword redundancy.

In this paper a new energy-efficient error control mechanism based on Redundant Residue Number System (RRNS) is proposed for Wireless Sensor Networks (WSNs). In general, WSNs suffer from burst errors due to their inherent nature. An error detection and correction approach has been developed to handle burst errors more efficiently. Residue encoders transform the sensed data to small-sized and independent code-words with redundant information. When an error is detected at the base station, a new module of remainder code-words will be requested from the encoder nodes. This approach creates spatial diversity against fading in a wireless channel. Overall, the proposed scheme results in saving transmission energy, adding negligible encoder energy consumption.

In this paper, the reconstruction of the feedback polynomial as well as the initial state of a linear feedback shift register (LFSR) in a synchronous scrambler placed after a channel encoder is studied. The study is first based on the assumption that the channel is noiseless and then extended to the noisy channel condition. The dual words, which are orthogonal to the codewords generated by the channel encoder, are used in the reconstruction algorithm. The number of bits required by the new algorithm is compared with another recently proposed algorithm and results show that the number of bits required to do the reconstruction can be significantly reduced.

Linear codes with good algebraic structures have been used in a number of cryptographic or information-security applications, such as wire-tap channels of type II and secret sharing schemes. For a code-based secret sharing scheme, the problem of determining the minimal access sets is reduced to finding the minimal codewords of the dual code. It is well known that the latter problem is a hard problem for an arbitrary linear code. Constant weight codes and two-weight codes have been studied in the literature, for their applications to secret sharing schemes. In this paper, we study a class of three-weight codes. Making use of the finite projective geometry, we will give a sufficient and necessary condition for a linear code to be a three-weight code. The geometric approach that we will establish also provides a convenient method to construct three-weight codes. More importantly, we will determine the minimal codewords of a three-weight code, making use of the geometric approach.

It is well known that in order to build linear scramblers and stream ciphers that are robust against correlation-based reconstruction, primitive polynomials which do not have sparse multiples of moderate degrees must be used. In this paper, the existence and density of such ‘good primitive polynomials’ are studied. Two theoretical lower bounds on the degree d of the primitive polynomial are derived. When d is larger than the first lower bound, there exists at least one primitive polynomial of degree d which does not have any sparse multiple of moderate degree and when d is larger than the second lower bound, it is almost guaranteed that a randomly chosen primitive polynomial of degree d does not have any sparse multiples of moderate degree. To make the lower bound tight, the distribution of the minimum degrees of sparse multiples of primitive polynomials is investigated in this paper. From comparison, it can be seen that the lower bounds obtained in this paper are much better than the previous results reported in the literature.

In this paper, the problem of reconstruction of the feedback polynomial in a linear scrambler is studied. Our work contains two parts. In the first part, schemes to improve the performance of an existing reconstruction algorithm are proposed. Simulation results show that both the detection capability and speed of the existing algorithm are significantly improved by using our proposed schemes. In the second part, the reconstruction of linear scramblers in the presence of channel noise is investigated. We consider flipped bits due to noise as well as insertion of bits in the scrambled bit sequence. For both cases, factors which affect the performance of the reconstruction algorithm are discussed.

The existing algorithm for reconstruction of the feedback polynomial in a linear scrambler relies on the assumption that the input sequence is produced by a biased memoryless source and the source bias is known and used for reconstruction. In this paper, the problem of reconstruction of the feedback polynomial in a linear scrambler without knowledge of the source bias is studied. An algorithm is proposed to reconstruct the scrambler without knowledge of the source bias and factors which affect the performance of this algorithm are discussed. A scheme which reduces the number of bits used in the reconstruction without affecting the detection capability of the reconstruction algorithm is also proposed in this paper.

A linear feedback shift register (LFSR) is a basic component of a linear scrambler and a stream cipher for a communication system. And primitive polynomials are used as the feedback polynomials of the LFSRs. In a non-cooperative context, the reverse-engineering of a linear scrambler and a stream cipher includes recovering the feedback polynomials and the LFSR's initial states (which are the secret keys in the case of stream ciphers). The problem of recovering the secret keys of stream ciphers has been extensively studied. For example, an effective approach for recovering a secret key is known as the correlation attack in the literature. The problem of reconstructing the feedback polynomials of a stream cipher and a linear scrambler has been studied recently. Both recovering the LFSR initial states by the above-mentioned correlation attack and reconstructing the feedback polynomials are highly dependent on an assumption, that is, they require that the feedback polynomials have sparse multiples of moderate degrees. Hence, in order to build linear scramblers and stream ciphers that are robust against reverse engineering, we should use primitive polynomials which do not have sparse multiples of moderate degrees. In this paper, we study the existence of primitive polynomials which do not have sparse multiples of moderate degrees, and the density of such primitive polynomials among all primitive polynomials. Our results on the existence and density of such primitive polynomials are better than the previous results in the literature.

We first present an equivalent definition of relative generalized Hamming weights of a linear code and its subcodes, and we develop a method using finite projective geometry. Making use of the equivalent definition and the projective-geometry method, all of the relative generalized Hamming weights of a 3-dimensional q-ary linear code and its subcodes will be determined.

The theory of algebraic-geometric codes with respect to the Hamming metric has been well developed. However, in many applications where non-binary signals are transmitted or stored the Lee metric is a more appropriate metric than the Hamming metric. In our previous work, we presented a polynomial-time Lee-metric decoding algorithm for algebraic-geometricable codes. Our algorithm generalizes the interpolation-based Lee-metric decoding algorithm for Reed-Solomon codes in the literature. In this paper, we derive an explicit upper bound on the Lee-error correcting radius of our decoding algorithm. The bound also applies to the Lee-metric Reed-Solomon decoding. As far as we know no such explicit bound is available in the literature.

Let F/sub q/[X/sub 1/,...,X/sub m/] denote the set of polynomials over F/sub q/ in m variables, and F/sub q/[X/sub 1/,...,X/sub m/]/sub /spl les/u/ denote the subset that consists of the polynomials of total degree at most u. Let H(T) be a nontrivial polynomial in T with coefficients in F/sub q/[X/sub 1/,...,X/sub m/]. A crucial step in interpolation-based list decoding of q-ary Reed-Muller (RM) codes is finding the roots of H(T) in F/sub q/[X/sub 1/,...,X/sub m/]/sub /spl les/u/. In this correspondence, we present an efficient root-finding algorithm, which finds all the roots of H(T) in F/sub q/[X/sub 1/,...,X/sub m/]/sub /spl les/u/. The algorithm can be used to speed up the list decoding of RM codes.

This paper describes the algebraic-geometric (AG) codes for the Lee metric and derives a lower bound for the minimum Lee distance of AG codes. A Lee-metric decoding algorithm for AG codes is also discussed. This algorithm gives a performance-complexity, which achieves an error-correcting capability.

The q-ary Reed-Muller (RM) codes RM/sub q/(u,m) of length n=q/sup m/ are a generalization of Reed-Solomon (RS) codes, which use polynomials in m variables to encode messages through functional encoding. Using an idea of reducing the multivariate case to the univariate case, randomized list-decoding algorithms for RM codes were given in and . The algorithm in Sudan et al. (1999) is an improvement of the algorithm in , it is applicable to codes RM/sub q/(u,m) with u<q/2 and works for up to E

A list decoding for an error-correcting code is a decoding algorithm that generates a list of codewords within a Hamming distance t from the received vector, where t can be greater than the error-correction bound. In previous work by M. Shokrollahi and H. Wasserman (see ibid., vol.45, p.432-7, March 1999) a list-decoding procedure for Reed-Solomon codes was generalized to algebraic-geometric codes. Recent work by V. Guruswami and M. Sudan (see ibid., vol.45, p.1757-67, Sept. 1999) gives improved list decodings for Reed-Solomon codes and algebraic-geometric codes that work for all rates and have many applications. However, these list-decoding algorithms are rather complicated. R. Roth and G. Ruckenstein (see ibid., vol.46, p.246-57, Jan. 2000) proposed an efficient implementation of the list decoding of Reed-Solomon codes. In this correspondence, extending Roth and Ruckenstein's fast algorithm for finding roots of univariate polynomials over polynomial rings, i.e., the reconstruct algorithm, we present an efficient algorithm for finding the roots of univariate polynomials over function fields. Based on the extended algorithm, we give an efficient list-decoding algorithm for algebraic-geometric codes.