Search

The article presents PUZZLE, a scalable secret-sharing-based mutual anonymity protocol for anonymous query issuance and file delivery for mobile peer-to-peer networks (MOPNETs) in ad hoc environments. PUZZLE achieves mutual anonymous communication with a lower cryptography processing overhead and higher degree of anonymity.

The secure end-to-end route discovery in the decentralized Mobile Adhoc Networks (MANETs) should have to meet the requirements of prevention of DoS attacks on data traffic, should be adaptive and fault tolerant and must have high speed, low energy overhead and scalability for future development. In this research a secure routing using antnet mechanism and mutual authentication using Elliptic Curve Cryptography (ECC) has been proposed to meet the above requirements. The common perception of public key cryptography is that it is not well suited for adhoc networks as they are very complex and slow. Against this popular belief, this research implements Elliptic Curve Cryptography - a public key cryptography scheme. ECC provides a similar level of security to conventional integer-based public-key algorithms, but with much shorter keys. Because of the shorter keys ECC algorithms run faster, require less space and consume less energy. These advantages make ECC a better choice of public key cryptography, especially for a resource constrained systems like MANETs. Using the antnet routing algorithm, the highly trustable route will be selected for data transfer and each Mobile Node (MN) in MANET maintains the trust value of its one-hop neighbors. The mutual authentication between source and destination is done by master key exchange using Elliptic Curve Cryptography (ECC). Key words: Mobile Adhoc Networks (MANETs), Elliptic Curve Cryptography (ECC), cluster head, virtual cluster, centralized authority, mobile node, Message Authentication Code (MAC), INTRODUCTION Adhoc networks have enormous impact on many aspects such as emergency medical care and military services where security of data is very important. The secure path establishment procedure plays [...]

Quantum Error Correction will be necessary for preserving coherent states against noise and other unwanted interactions in quantum computation and communication. We develop a general theory of quantum error correction based on encoding states into larger Hilbert spaces subject to known interactions. We obtain necessary and sufficient conditions for the perfect recovery of an encoded state after its degradation by an interaction. The conditions depend only on the behavior of the logical states. We use them to give a recovery operator independent definition of error-correcting codes. We relate this definition to four others: The existence of a left inverse of the interaction, an explicit representation of the error syndrome using tensor products, perfect recovery of the completely entangled state and an information theoretic identity. Two notions of fidelity and error for imperfect recovery are introduced, one for pure and the other for entangled states. The latter is more appropriate when using codes in a quantum memory or in applications of quantum teleportation to communication. We show that the error for entangled states is bounded linearly by the error for pure states. A formal definition of independent interactions for qubits is given. This leads to lower bounds on the number of qubits required to correct errors and a formal proof that the classical bounds on the probability of error-correcting codes applies to error correcting quantum codes, provided that the interaction is dominated by an identity component. Key words: The Heisenberg uncertainty principle, BB84 protocol, noise, quantum protocol, error code corrector, INTRODUCTION Within the past few years, quantum computation and communication have undergone a dramatic evolution. From being subjects of primarily academic interest, they have become fields having an enormous potential [...]

In this paper, a coding-theory construction of Cartesian authentication codes is presented. The construction is a generalization of some known constructions. Within the framework of this generic construction, several classes of authentication codes using certain classes of error-correcting codes are described. The authentication codes presented in this paper are better than known ones with comparable parameters. It is demonstrated that the construction is related to certain combinatorial designs, such as difference matrices and generalized Hadamard matrices. Index Terms--Authentication codes, coding theory, cryptography.

In this correspondence, we present a family of binary [2.sup.n] sequences of period 2([2.sup.n] - 1) where n is an integer, which can be seen as a generalization of nonlinear binary sequences obtained from [Z.sub.4] sequences and recently constructed GKW (Gold, Kasami, and Welch)-like sequences. The sequences have low correlations and are useful in code-division multiple-access (CDMA) communication systems and cryptography.

The importance and feasibility of applying a joint signal processing and cryptographic approach to multimedia encryption is discussed, to address the access control issues unique to multimedia applications. Two atomic encryption operations are proposed, and experiments show that by strategically integrating selective value encryption, intrabitplane shuffling and spatial permutation, the resulting system can achieve security, friendliness to delegate processing and bitrate overhead.

Abstract--With the exponential growth of networked system and application such as eCommerce, the demand for effective internet security is increasing. Cryptology is the science and study of systems for secret [...]

Recently, algebraic attacks have received a lot of attention in the cryptographic literature. It has been observed that a Boolean function f used as a cryptographic primitive, and interpreted as a multivariate polynomial over [F.sub.2], should not have low degree multiples obtained by multiplication with low degree onzero functions. In this paper, we show that a Boolean function having low nonlinearity is (also) weak against algebraic attacks, and we extend this result to higher order nonlinearities. Next, we present enumeration results on linearly independent annihilators. We also study certain classes of highly nonlinear resilient Boolean functions for their algebraic immunity. We identify that functions having low-degree subfunctions are weak in terms of algebraic immunity, and we analyze some existing constructions from this viewpoint. Further, we present a construction method to generate Boolean functions on n variables with highest possible algebraic immunity [n/2] (this construction, first presented at the 2005 Workshop on Fast Software Encryption (FSE 2005), has been the first one producing such functions). These functions are obtained through a doubly indexed recursive relation. We calculate their Hamming weights and deduce their nonlinearities; we show that they have very high algebraic degrees. We express them as the sums of two functions which can be obtained from simple symmetric functions by a transformation which can be implemented with an algorithm whose complexity is linear in the number of variables. We deduce a very fast way of computing the output to these functions, given their input. Index Terms--Algebraic attacks, annihilators, Boolean functions, nonlinearity, stream ciphers, Walsh spectrum.

We consider the Shannon cipher system in a setting where the secret key is delivered to the legitimate receiver via a channel with limited capacity. For this setting, we characterize the achievable region in the space of three figures of merit: the security (measured in terms of the equivocation), the compressibility of the cryptogram, and the distortion associated with the reconstruction of the plaintext source. Although lossy reconstruction of the plaintext does not rule out the option that the (noisy) decryption key would differ, to a certain extent, from the encryption key, we show, nevertheless, that the best strategy is to strive for perfect match between the two keys, by applying reliable channel coding to the key bits, and to control the distortion solely via rate-distortion coding of the plaintext source before the encryption. In this sense, our result has a flavor similar to that of the classical source-channel separation theorem. Some variations and extensions of this model are discussed as well. Index Terms--Cryptugraphy, eucryption, key distribution, Shannon cipher system, source-channel separation.

Cryptographic transformations are a fundamental building block in many security applications and protocols. To improve performance, several vendors market hardware accelerator cards. However, until now no operating system provided a mechanism that allowed both uniform and efficient use of this new type of resource. We present the OpenBSD Cryptographic Framework (OCF), a service virtualization layer implemented inside the operating system kernel, that provides uniform access to accelerator functionality by hiding card-specific details behind a carefully designed API. We evaluate the impact of the OCF in a variety of benchmarks, measuring overall system performance, application throughput and latency, and aggregate throughput when multiple applications make use of it. We conclude that the OCF is extremely efficient in utilizing cryptographic accelerator functionality, attaining 95% of the theoretical peak device performance and over 800 Mbps aggregate throughput using 3DES. We believe that this validates our decision to opt for ease of use by applications and kernel components through a uniform API and for seamless support for new accelerators. Furthermore, our evaluation points to several bottlenecks in system and operating system design: data copying between user and kernel modes, PCI bus signaling inefficiency, protocols that use small data units, and single-threaded applications. We identify some of these limitations through a set of measurements focusing on application-layer cryptographic protocols such as SSL. We offer several suggestions for improvements and directions for future work. We provide experimental evidence of the effectiveness of a new approach which we call operating system shortcutting. Shortcutting can improve the performance of application-layer cryptographic protocols by 27% with very small changes to the kernel. Categories and Subject Descriptors: D.4.6 [Operating Systems]: Cryptographic Controls; D.4.8 [Operating Systems]: Performance--Measurements General Terms: Security, Performance Additional Key Words and Phrases: Encryption, authentication, hash functions, digital signatures, cryptographic protocols

Byline: Mark D. Corner (001), Brian D. Noble (001) Abstract: Laptops are vulnerable to theft, greatly increasing the likelihood of exposing sensitive files. Unfortunately, storing data in a cryptographic file system does not fully address this problem. Such systems ask the user to imbue them with long-term authority for decryption, but that authority can be used by anyone who physically possesses the machine. Forcing the user to frequently reestablish his identity is intrusive, encouraging him to disable encryption. This tension between usability and security is eliminated through Transient Authentication, in which a small hardware token continuously authenticates the user's presence to the laptop over a short-range, wireless link. Whenever the laptop needs decryption authority, it acquires it from the token; authority is retained only as long as necessary. With careful key management, ZIA imposes an overhead of less than 7% for representative workloads, though some infrequent operations suffer greater overheads. The largest file cache on our hardware can be re-encrypted within five seconds of the user's departure, and restored in just over six seconds after detecting the user's return. This secures the machine before an attacker can gain physical access, but recovers full performance before a returning user resumes work. Key granularity plays an important role in determining performance; assigning encryption keys on a per-directory basis limits the cost of an exposed key while maintaining acceptable overhead. Author Affiliation: (001) Department of Electrical Engineering and Computer Science, University of Michigan, Ann Arbor, MI, USA Article History: Registration Date: 13/12/2004

In this paper a general methodology for designing chaotic and hyperchaotic cryptosystems is developed. The basic idea is to make the decrypter a nonlinear observer for the state of the encrypter. Referring to this concept, some propositions are given which enable the plaintext to be retrieved if proper structural properties of the chaotic system hold. The proposed tool proves to be powerful and flexible, since a wide class of cryptosystems can be designed by exploiting different chaotic and hyperchaotic circuits. The advantages of the suggested approach are illustrated in detail. In particular, the utilization of hyperchaos-based cryptosystems, as well as the increased complexity of the transmitted signal, make a contribution to the development of communication systems with higher security. Index Terms - Cryptosystems design, observers, synchronization of hyperchaotic systems.

We propose a scheme to implement secure digital mobile communications. The scheme can both enable multiple users to hold a secure teleconference and also resolve the problem of allowing a participant to join dynamically or to quit a teleconference already in progress. Essentially, teleconference is a synchronous collaboration session in which participants at remote locations cooperate through wireless communications. Two requirements for the system are: privacy and authentication. Privacy signifies that an eavesdropper cannot intercept conversations of a conference. Authentication ensures that the service is not obtained fraudulently in order to avoid usage charge usage. We present a conference key distribution scheme for digital mobile communications, according to which users can share a common secret key to hold a secure teleconference over a public channel. The participants need not alter their secret information when a participant joins late or quits the conference early. Index Terms - Cryptography, mobile communications, security, teleconference.

The growing prevalence in the distribution of copyright materials is sustaining a need for tamper-proof electronic watermarking. Such requirements can be met by a watermark that consists of an independent and identically distributed Gaussian random vector inserted imperceptibly into the work being protected. Methods of inserting tamper-proof watermarks are suggested.