Information security for sensors by overwhelming random sequences and permutations

We consider the problem of constructing randomness extractors that are locally computable; that is, read only a small number of bits from their input. As recently shown by Lu locally computable extractors directly yield secure private-key cryptosystems in Maurer’s bounded-storage model. We suggest a general “sample-then-extract” approach to constructing locally computable extractors: use essentially any randomness-efficient sampler to select bits from the input and then apply any extractor to the selected bits. Plugging in known sampler and extractor constructions, we obtain locally computable extractors, and hence cryptosystems in the bounded-storage model, whose parameters improve upon previous constructions. We also provide lower bounds showing that the parameters we achieve are nearly optimal. The correctness of the sample-then-extract approach follows from a fundamental lemma of Nisan and Zuckerman, which states that sampling bits from a weak random source roughly preserves the min-entropy rate. We also present a refinement of this lemma, showing that the min-entropy rate is preserved up to an arbitrarily small additive loss, whereas the original lemma loses a logarithmic factor.

The theory of computational complexity is based on the tradeoff between two computational resources, memory space and computer time. This paper investigates the physical counterparts of these resources. Memory space is the number of bits of information required by a computer over the course of a computation. Physically, information is intimately connected with entropy: entropy can be thought of as random bits of information. The physical analogue of the amount of memory space required for a computation, Ф- SPACE, is the difference between the maximum entropy Smax of the computing system and its actual entropy, S.Ф-SPACE = S - Smax is the thermodynamic depth of the computation. Ф-SPACE is the maximum number of bits of memory space available for a physical system to perform computation. In conventional computational complexity theory, computer time is identified as the number of elementary logical operations (AND, OR, NOT, COPY) required to perform the computation. The physical analogue of time computational complexity is simply the time required for the physical computing system to perform the computation. In order to obtain a number that measures the number of physical operations that can be performed by the system over time t, we define Ф-TIME to be proportional to the computation time multiplied by the energy E of the computing system over the course of the computation: Ф-TIME = 2Et/πħ. Here, the proportionality factor 2/πħ is chosen to match the time it takes a computing system with energy E to flip a bit in time t. Ф-TIME is thus the number of bit flips that can take place in an information processing system. In addition, we propose a novel measure of physical complexity that combines these measures. The free energy F = E - TS of a system is the amount of energy that is available to do useful work - as opposed to the energy bound up in the thermal fluctuations of heat. We define the free complexity to be the free energy × time product, 2Ft/πħ required by a physical system to perform a computation. Physical spatial and temporal complexity provide upper bounds on the amount of computation that can be performed by any physical system. We discuss the implications of physical complexity for the computational complexity hierarchy, in particular, we show that in the presence of errors in the computation, Ф-SPACE is proportional Ф-TIME. We apply the resulting theory of physical computational complexity to analyze the computational power of black holes: exactly half of the energy of a black hole is available for physical computation.

In this paper we propose a new adaptive block based compressed domain data hiding scheme which can embed relatively large number of secret bits without significant perceptual distortion in video domain. Macro blocks are selected for embedding on the basis of low inter frame velocity. From this subset, the blocks with high prediction error are selected for embedding. The embedding is done by modifying the quantized DCT AC coefficients in the compressed domain. The number of coefficients (both zero and non zero) used in embedding is adaptively determined using relative strength of the prediction error block. Experimental results show that this blind scheme can embed a relatively large number of bits without degrading significant video quality with respect to Human Visual System (HVS).

Information hiding based on text has become the hottest and most discussed aspect of steganography in recent years, because it eases communication and consumes less memory compared to other types. The lack of redundant information in a text file makes it difficult to hide secret bits into a carrier message (CM) without being noticeable. Therefore, the total amount of hidden bits embeddable in a CM contributes immensely to the system efficiency. Today, individuals share information online with the fear that it could be destroyed by third parties. To achieve a structured text hiding system with high embedding capacity, imperceptibility, robustness and high security concurrently, securing sensitive data through encryption is not enough because attackers are able to suspect that a communication channel exist between the sender and the receiver. Therefore, this paper combines both steganography and cryptography to protect our shared information and to achieve a strong and highly secured non understandable text hiding system. We proposed a method which uses pairs of Zero Width Characters (ZWC) to represent each 4-bit binary classification which provides a high embedding capacity and reduces computational complexity than previous methods. The embedding is done by placing the invisible strings of the secret message (SM) into a single position of the open spaces in the CM which provides high invisibility compared to the reviewed methods. One Time Pad (OTP) and XOR bitwise encryption is used to encrypt the inverted message before the embedding process which provides end-to-end security to the system. The experiment shows that the proposed method provides a very high embedding capacity and high robustness than other literature reviewed.

In recent years, data hiding techniques have emerged as a prominent area of research due to the increasing demand for information security. Existing data hiding techniques typically do not prioritize the verification of the correctness of the extracted data, nor do they attempt to rectify any erroneous information extracted. This paper presents a simple yet effective method by which a recipient can perform error detection and correction on extracted data. Prior to data embedding, a preprocess is applied to secret data. After converting the secret data to a data stream, a data hider categorizes adjacent and identical bits within the data stream into groups. The number of these bits is then recorded as an indicator to extract information and perform error detection and correction. The number of bits in each group is adjusted to ensure that it is an odd number. Moreover, the collected indicator data stream is encoded using (7,4) Hamming code to compact the recorded information. Finally, the concatenation of the encoded indicator and the encoded secret is embedded into the multiple least significant bits (LSBs) of the original image pixels. As for the receiver, error correction can be applied based on the indicator after the extraction of the encoded data. Experimental results demonstrate that this method allows the data receiver to detect and correct errors while maintaining a certain level of embedding capacity and image quality. In terms of image quality, this method exhibits superior performance compared to existing research when the embedded data volume is relatively small.

This paper proposes an efficient two-stage beamforming and scheduling algorithm for the limited-feedback cooperative multi-point (CoMP) systems. The system includes multiple base-stations cooperatively transmitting data to a pool of users, which share a rate-limited feedback channel for sending back the channel state information (CSI). The feedback mechanism is divided into two stages that are used separately for scheduling and beamforming. In the first stage, the users report their best channel gain from all the base-station antennas and the basestations schedule the best user for each of their antennas. The scheduled users are then polled in the second stage to feedback their quantized channel vectors. The paper proposes an analytical framework to derive the bit allocation between the two feedback stages and the bit allocation for quantizing each user's CSI. For a total number of feedback bits B, it is shown that the number of bits assigned to the second feedback stage should scale as log B. Furthermore, in quantizing channel vectors from different base-stations, each user should allocate its feedback budget in proportion to the logarithm of the corresponding channel gains. These bit allocation are then used to show that the overall system performance scales double-logarithmically with B and logarithmically with the transmit SNR. The paper further presents several numerical results to show that, in comparison with other beamforming-scheduling algorithms in the literature, the proposed scheme provides a consistent improvement in downlink sum rate and network utility. Such improvements, in particular, are achieved in spite of a significant reduction in the beamforming-scheduling computational complexity, which makes the proposed scheme an attractive solution for practical system implementations.

Perkembangan teknologi informasi yang semakin pesat memberi pengaruh yang besar hamper diserluruh aspek kehidupan manusia. Tentunya tingkat keamanan yang tinggi sangat diperlukan agar informasi tersebut tidak dapt diakses oleh orang yang tidak berkepentingan. Masalah pengiriman pesan atau data merupakan salah satu hal yan sangat penting, karena data sangat rentang terhadap tindakan kejahatan komputer. Kriptografi super enkripsi dapat menjadi salah satu solusi untuk mencegah tindakan kejahatan. Algoritma One Time Pad dan Beaufort Chiper merupakan salah satu algoritma yang dapat digunakan untuk menjaga kerahasiaan data, One Time Pad adalah algoritma yang menggunakan perhitungan XoR dalam enkripsi dan dekripsi sedangkan Beaufort Chiper adalah algoritma yang menggunakan perhitungan modulo. Jika kedua algoritma ini disatukan dalam sebuah aplikasi keamanan data, maka akan sulit untuk dibobol atau diambil oleh orang yan tidak bertanggung jawab.

Random numbers are essential for our modern information-based society. Unlike frequently used pseudo-random generators, physical random number generators do not depend on deterministic algorithms but rather on a physical process to provide true randomness. In this work we present a conceptually simple optical quantum random number generator that features special characteristics necessary for application in a loophole-free Bell inequality test, namely: (1) very short latency between the request for a random bit and time when the bit is generated; (2) all physical processes relevant to the bit production happen after the bit request signal; and (3) high efficiency of producing a bit upon a request (100% by design). This generator is characterized by further desirable characteristics: ability of high bit generation rate, possibility to use a low detection-efficiency photon detector, a high ratio of number of bits per detected photon (≈2) and simplicity of the bit generating process. Generated sequences of random bits pass NIST STS test without further postprocessing.

A semiconductor laser with distributed feedback from a fiber Bragg grating (FBG) is investigated for random bit generation (RBG). The feedback perturbs the laser to emit chaotically with the intensity being sampled periodically. The samples are then converted into random bits by a simple postprocessing of self-differencing and selecting bits. Unlike a conventional mirror that provides localized feedback, the FBG provides distributed feedback which effectively suppresses the information of the round-trip feedback delay time. Randomness is ensured even when the sampling period is commensurate with the feedback delay between the laser and the grating. Consequently, in RBG, the FBG feedback enables continuous tuning of the output bit rate, reduces the minimum sampling period, and increases the number of bits selected per sample. RBG is experimentally investigated at a sampling period continuously tunable from over 16 ns down to 50 ps, while the feedback delay is fixed at 7.7 ns. By selecting 5 least-significant bits per sample, output bit rates from 0.3 to 100 Gbps are achieved with randomness examined by the National Institute of Standards and Technology test suite.

We present substantial extensions of works [1], [2], and all previous works, on encryption in the bounded storage model introduced by Maurer in [25]. The major new result is that the shared secret key employed by the sender Alice andthe receiver Bob can be re-used to send an exponential number of messages, against strong adaptive attacks. This essential step enhances the usability of the encryption method, and also allows strong authentication andnon-malleability described below. We give an encryption scheme that is provably secure against adaptive attacks by a computationally unbounded adversary in the bounded storage model. In the model, a sender Alice and a receiver Bob have access to a public random string α, and share a secret key s. Alice and Bob observe α on the fly, andb y use of s extract bits from which they create a one-time pad X used to encrypt M as C = X⊕M. The size of the secret key s is ∣s∣ = klog2 ∣α∣, where k is a security parameter. An Adversary AD can compute andstore any function A 1(α) = η, subject to the bound on storage ∣η∣ ≤γ. ·∣α∣, γ < 1, and captures C. Even if AD later gets the key s and is computationally unbounded, the encryption is provably secure. Assume that the key s is repeatedly used with successive strings α1, α2, ... to produce encryptions C 1, C 2, ... of messagesM 1,M 2, .... AD computes η1 = A 1(α1), obtains C 1, and gets to see the first message M 1. Using these he computes andstores η2 = A 1(α2, α1, C 1,M 1), and so on. When he has stored ηl andcaptured C l, he gets the key s (but not M l). The main result is that the encryption C l is provably secure against this adaptive attack, where l, the number of time the secret key s is re-used, is exponentially large in the security parameter k. On this we base non-interactive protocols for authentication and non-malleability. Again, the shared secret key used in these protocols can be securely re-usedan exponential number of times against adaptive attacks. The method of proof is stronger than the one in [1], [2], and yields ergodic results of independent interest. We discuss in the Introduction the feasibility of the bounded storage model, and outline a solution. Furthermore, the existence of an encryption scheme with the provable strong security properties presented here, may prompt other implementations of the bounded storage model.

It has long been known that cryptographic schemes offering provably unbreakable security exist, namely the One Time Pad (OTP). The OTP, however, comes at the cost of a very long secret key - as long as the plain-text itself. In this paper we propose an encryption scheme which we (boldly) claim offers the same level of security as the OTP, while allowing for much shorter keys, of size polylogarithmic in the computing power available to the adversary. The Scheme requires a large sequence of truly random words, of length polynomial in the both plain-text size and the logarithm of the computing power the adversary has. We claim that it ensures such an attacker cannot discern the cipher output from random data, except with small probability. We also show how it can be adapted to allow for several plain-texts to be encrypted in the same cipher output, with almost independent keys. Also, we describe how it can be used in lieu of a One Way Function.

To enhance the payload of secret data a scheme on the basis of least significant bit (LSB) substitution cascaded with pixel value differencing (PVD) has been proposed in this paper. Firstly secret bits are embedded using PVD method where smooth areas obtain small number of bits and higher bits in the edged area. Then bits are also embedded in the same pixel block by applying LSB replacement method as a cascading manner. The technique ensures more hiding capacity along with security as two methods are applied as cascaded manner on the same pixel block. Experimental result shows that proposed method can hide nearly double amount of secret data, compared to PVD method with good visual quality of stego-images.

Despite great effort from the research community, wireless networks still operate below full capacity. To increase the network throughput it is important to study algorithms that select communication requests that can decode their signals despite mutual interference. In this paper, we study the joint problem of data rate assignment and link scheduling in the physical interference model. The objective of the problem is to maximize the total number of bits transmitted in one time slot. By constructing an intermediate network representation through a disk graph, we prove that a constant approximation solution can be computed in polynomial time. Finally, we propose a parallel implementation of a polynomial-time approximation scheme and show through simulations that the one-slot throughput of a wireless network can be significantly improved by using variable data rates.

In the simultaneous message model, two parties holding n-bit integers x,y send messages to a third party, the referee, enabling him to compute a boolean function f(x,y). Buhrman et al [3] proved the remarkable result that, when f is the equality function, the referee can solve this problem by comparing short sent by the two parties, i.e., there exists a quantum protocol using only O(log n) bits. This is in contrast to the well-known classical case for which Ω(n1/2) bits are provably necessary for the same problem even with randomization. In this paper we show that short quantum fingerprints can be used to solve the problem for a much larger class of functions. Let R,pub(f) denote the number of bits needed in the classical case, assuming in addition a common sequence of random bits is known to all parties (the public coin model). We prove that, if R,pub(f)=O(1), then there exists a quantum protocol for f using only O(log n) bits. As an application we show that O(log n) quantum bits suffice for the bounded Hamming distance function, defined by f(x,y)=1 if and only if x and y have a constant Hamming distance d or less.

In this report, we present an encryption algorithm that can be used for hardware-implemented applications to secure data communications, this encryption algorithm is based on hiding a number of bits from plain text message into a random vector of bits, the locations of the hidden bits are determined by a key known to the sender and receiver, we call this algorithm hybrid hiding encryption algorithm (HHEA). The name demonstrates the two basic operations of this algorithm, these operations include inserting part of the plaintext bits into a cover to hide it from recognition, that is, there are no conventional operations on the ciphered text, just plain hiding in a random bit string, the name hybrid is used to show that the algorithm has built-in features that are inherited from data hiding techniques or steganography