共查询到20条相似文献,搜索用时 890 毫秒
1.
TheSpectrumoftheSquareofaSynchronousRandomPulseTraininImpulseNoiseEnvironments¥YanJingwen;QiLei;andYueZhengui(DepartmentofRad... 相似文献
2.
Sourav Sen Gupta Subhamoy Maitra Goutam Paul Santanu Sarkar 《Journal of Cryptology》2014,27(1):67-108
RC4 has been the most popular stream cipher in the history of symmetric key cryptography. Its internal state contains a permutation over all possible bytes from 0 to 255, and it attempts to generate a pseudo-random sequence of bytes (called keystream) by extracting elements of this permutation. Over the last twenty years, numerous cryptanalytic results on RC4 stream cipher have been published, many of which are based on non-random (biased) events involving the secret key, the state variables, and the keystream of the cipher. Though biases based on the secret key are common in RC4 literature, none of the existing ones depends on the length of the secret key. In the first part of this paper, we investigate the effect of RC4 keylength on its keystream, and report significant biases involving the length of the secret key. In the process, we prove the two known empirical biases that were experimentally reported and used in recent attacks against WEP and WPA by Sepehrdad, Vaudenay and Vuagnoux in EUROCRYPT 2011. After our current work, there remains no bias in the literature of WEP and WPA attacks without a proof. In the second part of the paper, we present theoretical proofs of some significant initial-round empirical biases observed by Sepehrdad, Vaudenay and Vuagnoux in SAC 2010. In the third part, we present the derivation of the complete probability distribution of the first byte of RC4 keystream, a problem left open for a decade since the observation by Mironov in CRYPTO 2002. Further, the existence of positive biases towards zero for all the initial bytes 3 to 255 is proved and exploited towards a generalized broadcast attack on RC4. We also investigate for long-term non-randomness in the keystream, and prove a new long-term bias of RC4. 相似文献
3.
We construct two efficient Identity-Based Encryption (IBE) systems that admit selective-identity security reductions without
random oracles in groups equipped with a bilinear map. Selective-identity secure IBE is a slightly weaker security model than
the standard security model for IBE. In this model the adversary must commit ahead of time to the identity that it intends
to attack, whereas in an adaptive-identity attack the adversary is allowed to choose this identity adaptively. Our first system—BB1—is based on the well studied decisional bilinear Diffie–Hellman assumption, and extends naturally to systems with hierarchical
identities, or HIBE. Our second system—BB2—is based on a stronger assumption which we call the Bilinear Diffie–Hellman Inversion assumption and provides another approach
to building IBE systems. 相似文献
4.
WANG Yu-hua NIU Li-ping 《半导体光子学与技术》2006,12(2):117-122
With the rapid development of cryptography, the strength of security protocols and encryption algorithms consumedly relies on the quality of random number. In many cryptography applications, higher speed is one of the references required. A new security random number generator architecture is presented. Its philosophy architecture is implemented with FPGA, based on the thermal noise and linear feedback shift register(LFSR). The thermal noise initializes LFSRs and is used as the disturbed source of the system to ensure the unpredictability of the produced random number and improve the security strength of the system. Parallel LFSRs can produce the pseudo-random numbers with long period and higher speed. The proposed architecture can meet the requirements of high quality and high speed in cryptography. 相似文献
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Generally speaking, parameter selection in all cryptographic algorithms and protocols is a mixture of art and science and exerts various subtle influences on a system, which is related to application requirements, security policies, the compromise between security and the overheads of computation, storage and communications, the balance between security and availability, and to the efficiency of software /hardware implementation, etc. Usually, simplistic, insecure or impractical textbook crypto… 相似文献
6.
1 IntroductionInthepastthirtyyears,randomaccesstech niqueshavewidelybeenappliedinsatellitesystems,groundradionetworks,andcomputerandcommuni cationsystems.TheoriginalrandomaccessschemewasALOHAsystemwhichwasintroducedbyAbramsonin 1 970 .Thissystemschemewassim… 相似文献
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YANG Jun ZHOU Xian-wei QIN Bo-ping 《中国电子科技》2006,4(1):55-58
The EIGamal algorithm, which can be used for both signature and encryption, is of importance in public-key cryptosystems. However, there has arisen an issue that different criteria of selecting a random number are used for the same algorithm. In the aspects of the sufficiency, necessity, security and computational overhead of parameter selection, this paper analyzes these criteria in a comparative manner and points out the insecurities in some textbook cryptographic schemes. Meanwhile, in order to enhance security a novel generalization of the EIGamal signature scheme is made by expanding the range of selecting random numbers at an acceptable cost of additional computation, and its feasibility is demonstrated. 相似文献
8.
WANG Bang-ju WANG Yu-hua NIU Li-ping ZHANG Huan-guo 《半导体光子学与技术》2007,13(2):164-168
Random numbers play an increasingly important role in secure wire and wireless communication. Thus the design quality of random number generator(RNG) is significant in information security. A novel pseudo RNG is proposed for improving the security of network communication. The back propagation neural network(BPNN) is nonlinear, which can be used to improve the traditional RNG. The novel pseudo RNG is based on BPNN techniques. The result of test suites standardized by the U.S shows that theRNGcan satisfy the security of communication. 相似文献
9.
AFrequency-DiversitySpread-SpectrumMultipleAccessSystemwithRandomSignatureSequencesCaoYewen;XiangHaige(PekingUniversity,Beiji... 相似文献
10.
CHEN Wei-cheng XU Wen-cheng 《半导体光子学与技术》2006,12(4):224-227,237
Periodical polarization modulation scheme is proposed to suppress timing jitters induced by frequency fluctuations between two polarization components of solitons. In periodical polarization modulation scheme, the polarization states of the soliton are modulated to excite equally for suppressing timing jitters induced by two unequal polarization components in the soliton trapping. Moreover, polarization modulation can weaken the effect of random birefringence on the soliton pulses in each relay distance. The numerical result shows that the soliton timing jitters are suppressed by our proposed method. 相似文献
11.
A Frequency—Diversity Spread—Spectrum Multiple Access System with Random Signature Sequences 总被引:1,自引:0,他引:1
CaoYewen XiangHaige 《通信学报》1995,16(4):56-62
A new scheme for the spread-spectrum multiple access system named Frequency-Diver-sity Spread-Spectrum Multiple Access(FD-DDMA)system,is proposed.In this FD-SSMA sys-tem,the same information will be modulated on a group of mutually orthogonal frequency compo-nents(carriers)with a random signature sequence at the same time,and it will be demodulated by a coherent receiver for every component and then incorporated (ad if using frequency diversity)on the basis of this random sequence.The spectrum of the modulated signal is very close to that of a white-noise in a wider frequency band due to orthogonality for all frequency components and prop-erty of the random sequence,the system becomes a spread-spectrum one.The (Inverse)Fast Froier Transform(IFFT,FFT)can be applied in the system ,which provides additional flexibility.The performance in an asynchronous mode,such as ability of multiusers,anti-interferences ,is an-alyzed. 相似文献
12.
Susan Meñez Aspera Hideaki Kasai Hirofumi Kishi Nobuyoshi Awaya Shigeo Ohnishi Yukio Tamai 《Journal of Electronic Materials》2013,42(1):143-150
The resistance random access memory (RRAM?) device, with its electrically induced nanoscale resistive switching capacity, has attracted considerable attention as a future nonvolatile memory device. Here, we propose a mechanism of switching based on an oxygen vacancy migration-driven change in the electronic properties of the transition-metal oxide film stimulated by set pulse voltages. We used density functional theory-based calculations to account for the effect of oxygen vacancies and their migration on the electronic properties of HfO2 and Ta/HfO2 systems, thereby providing a complete explanation of the RRAM? switching mechanism. Furthermore, computational results on the activation energy barrier for oxygen vacancy migration were found to be consistent with the set and reset pulse voltage obtained from experiments. Understanding this mechanism will be beneficial to effectively realizing the materials design in these devices. 相似文献
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Bishnu P. Pal Sonali Dasgupta M.R.Shenoy Alexej Sysoliatin 《光电子快报》2006,2(5):342-344
Nonlinear optical effects such as self-phase modula-tion,four-wave mixing,cross-phase modulation,sti mula-ted Raman scattering,together with appropriate tempo-ral dispersion profileinan optical fiber couldsignificant-ly broaden ( >100 nm) the spectrumof a… 相似文献
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《III》1997,10(7):22-25
Throughout the past year III–Vs Review has been reporting on the starting developments within the field of blue emitting optoelectronics. Previous years saw a re-awakening of the science and commercial pursuit of what had been dismissed as a cul de sac in compound semiconductors. 1997 saw confirmation of the blue-green laser diode as an operational device from researchers worldwide, both in the academic laboratories and in industry. As the year closes and we look forward to the ‘wash-up’ celebration at the ‘MRS Fall Meeting Nitride Workshop’, Roy Szweda reports on the very latest developments in this exciting field. 相似文献
17.
The radiation pattern of an open-ended co-axial line excited in the TEM mode in a plasma column having a central conductor along the axis is studied. The field distribution at the open-end cross-section of the co-axial line is assumed to be equivalent to the vector sum of magnetic current rings of various radii, ranging from the outer radius of the inner conductor to the inner radius of the outer conductor of the co-axial line at the open end. The radiation field is obtained as a vector sum of field components duo to individual rings of magnetic current. This type of configuration gives rise to a veil-enhanced radiation peak near and before the critical angle. The amplitude of the radiation peak depends upon the dimensions of the plasma column, the diameter of the central conductor and the inner diameter of the outer conductor of the coaxial line at the open end. Its direction can be changed by changing the plasma density. Based upon these results it is proposed to develop an electronically scannable narrow-beam plasma antenna system. 相似文献
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研究了一种基于硅悬臂梁谐振器的新型气体传感器.该传感器在敏感环境中,可同时获得敏感膜电导率和质量变化,测量被测气体分子的荷质比,具有高灵敏度和高选择性.根据这一原理,针对气体传感器的需求,设计了硅悬臂梁谐振器化学传感器结构,进行了仿真优化,并采用MEMS表面牺牲层工艺制备该器件,激光频率仪测量验证了该微型谐振梁的谐振频率. 相似文献