High Speed Networking Security: Design and Implementation of Two New DDP-Based Ciphers

Using Data-Dependent (DD) Permutations (DDP) as main cryptographic primitive two new ciphers are presented: ten-round Cobra-H64, and twelve-round Cobra-H128. The designed ciphers operate efficiently with different plaintext lengths, 64 and 128-bit, for Cobra-H64 and Cobra-H128, respectively. Both of them use very simple key scheduling that defines high performance, especially in the case of frequent key refreshing. A novel feature of Cobra-H64 and Cobra-H128 is the use of the Switchable Operations which prevent the weak keys. The offered high-level security strength does not sacrifice the implementation performance, of both ciphers. Architecture, design and hardware implementation of the two ciphers are presented. The synthesis results for both FPGA and ASIC implementations prove that Cobra-H64 and Cobra-H128 are very flexible and powerful new ciphers, especially for high-speed networks. The achieved hardware performance and the implementation area cost of Cobra-H64 and Cobra-H128 are compared with other ciphers, used in security layers of wireless protocols (Bluetooth, WAP, OMA, UMTS and IEEE 802.11). From these comparisons it is proven that the two proposed are flexible new ciphers with better performance in most of the cases, suitable for wireless communications networks of present and future.     

A novel approach to enable decorrelating multiuser detection without matrix inversion operations

This paper proposes a non‐matrix inversion based algorithm to implement decorrelating detection (DD), namely quasi‐decorrelating detector (QDD), which uses truncated matrix series expansion to overcome the problems associated with the matrix inversion in DD, such as noise enhancement, computational complexity and matrix singularity, etc. Two alternative QDD implementation schemes are presented in this paper; one is to use multi‐stage feedforward filters and the other is to use an nth order single matrix filter (neither of which involves matrix inversion). In addition to significantly reduced computational complexity if compared with DD, the QDD algorithm offers a unique flexibility to trade among MAI suppression, near‐far resistance and noise enhancement depending on varying system set‐ups. The obtained results show that the QDD outperforms DD in either AWGN or multipath channel if a proper number of feed‐forward stages can be used. We will also study the impact of correlation statistics of spreading codes on the QDD's performance with the help of a performance‐determining factor derived in the paper, which offers a code‐selection guideline for the optimal performance of QDD algorithm. Copyright © 2004 John Wiley & Sons, Ltd.     

分组密码算法的三种硬件实现结构及性能分析

针对分组密码算法,研究了反复循环,循环展开和流水线三种实现结构,分析了三种结构下系统的资源占用、吞吐率、最高工作频率等参数,以求在各种不同应用环境,找出满足其需求的实现方案.以3DES为例分别实现了这三种结构,最后给出了基于Altera公司的CYCLONE系列FPGA的实现结果,对结果进行了比较和分析.     

基于动量项先验信噪比估计的语音增强算法的研究

先验信噪(SNR,Signal Noise Ratio)估计的精度影响着语音增强算法的性能。直接判决算法 (DD, Decision Directed)算法的计算简单且音乐噪声残留少,是最常用的先验信噪比估计算法,但是,该算法估计的增强语音语音失真严重。本文首先介绍了语音增强算法的基本理论并分析了DD算法、TSNR算法和融入动量项算法,然后运用MATLAB软件进行实验仿真,对比分析了融入动量项算法的性能优势。     

Cobra-H64/128算法的相关密钥-差分攻击

本文研究了Cobra-H64/128分组密码算法在相关密钥-差分攻击下的安全性.针对Cobra-H64算法,利用新构造的相关密钥-差分路径和CP逆变换存在的信息泄露规律给出攻击算法1,恢复出了全部128bit密钥,相应的计算复杂度为2^40.5次Cobra-H64算法加密,数据复杂度为2^40.5个选择明文,存储复杂度为2^22bit,成功率约为1;针对Cobra-H128算法,利用新构造的相关密钥-差分路径给出攻击算法2,恢复出了全部256bit密钥,相应的计算复杂度为2^76次Cobra-H128算法加密,数据复杂度为2^76个选择明文,存储复杂度为2^16.2bit.分析结果表明,Cobra-H64/128算法在相关密钥-差分攻击条件下是不安全的.     

A fast and efficient color image enhancement method based on fuzzy-logic and histogram

A new fuzzy logic and histogram based algorithm for enhancing low contrast color images has been proposed here. The method is computationally fast compared to conventional and other advanced enhancement techniques. It is based on two important parameters M and K, where M is the average intensity value of the image, calculated from the histogram and K is the contrast intensification parameter. The given RGB image is converted into HSV color space to preserve the chromatic information contained in the original image. To enhance the image, only the V component is stretched under the control of the parameters M and K. The proposed method has been compared with conventional contrast enhancement techniques as well as with advanced algorithms. All the above techniques were based on the principle of transforming the skewed histogram of the original image into a uniform histogram. The performance of the different contrast enhancement algorithms are evaluated based on the visual quality, Tenengrad, CII and the computational time. The inter comparison of different techniques was carried out on different low contrast color images. Based on the performance analysis, we advocate that our proposed Fuzzy Logic method is well suited for contrast enhancement of low contrast color images.     

FPGA Implementation and Energy Cost Analysis of Two Light-Weight Involutional Block Ciphers Targeted to Wireless Sensor Networks

In this paper, we investigate the energy cost of the FPGA implementation of two cryptographic algorithms targeted to wireless sensor networks (WSNs). Recent trends have seen the emergence of WSNs using sensor nodes based on reconfigurable hardware, such as a field-programmable gate arrays (FPGAs), thereby providing flexible functionality with higher performance than classical microcontroller based sensor nodes. In our study, we investigate the hardware implementation of involutional block ciphers since the characteristics of involution enables performing encryption and decryption using the same circuit. This characteristic is particularly appropriate for a wireless sensor node which requires the function of both encryption and decryption. Further, in order to consider the suitability of a cipher for application to a wireless sensor node, which is an energy constrained device, it is most critical to consider the cost of encryption in terms of energy consumption. Hence, we choose two involutional block ciphers, KHAZAD and BSPN, and analyze their energy efficiency for FPGA implementation.     

一种面向序列密码的混合粒度并行运算单元

针对可重构密码处理器对于不同域上的序列密码算法兼容性差、实现性能低的问题,该文分析了序列密码算法的多级并行性并提出了一种反馈移位寄存器(FSR)的预抽取更新模型。进而基于该模型设计了面向密码阵列架构的可重构反馈移位寄存器运算单元(RFAU),兼容不同有限域上序列密码算法的同时,采取并行抽取和流水处理策略开发了序列密码算法的反馈移位寄存器级并行性,从而有效提升了粗粒度可重构阵列(CGRA)平台上序列密码算法的处理性能。实验结果表明与其他可重构处理器相比,对于有限域(GF)(2)上的序列密码算法,RFAU带来的性能提升为23%～186%;对于GF(2u)域上的序列密码算法,性能提升达约66%～79%,且面积效率提升约64%～91%。     

Robust Least Squares Constant Modulus Algorithm to Signal Steering Vector Mismatches

The linearly constrained least squares constant modulus algorithm (LSCMA) may suffer significant performance degradation and lack robustness in the presence of the slight mismatches between the actual and assumed signal steering vectors, which can cause the serious problem of desired signal cancellation. To account for the mismatches, we propose a doubly constrained robust LSCMA based on explicit modeling of uncertainty in the desired signal array response and data covariance matrix, which provides robustness against pointing errors and random perturbations in detector parameters. Our algorithm optimizes the worst-case performance by minimizing the output SINR while maintaining a distortionless response for the worst-case signal steering vector. The weight vector can be optimized by the partial Taylor-series expansion and Lagrange multiplier method, and the optimal value of the Lagrange multiplier is iteratively derived based on the known level of uncertainty in the signal DOA. The proposed implementation based on iterative minimization eliminates the covariance matrix inversion estimation at a comparable cost with that of the existing LSCMA. We present a theoretical analysis of our proposed algorithm in terms of convergence, SINR performance, array beampattern gain, and complexity cost in the presence of random steering vector mismatches. In contrast to the linearly constrained LSCMA, the proposed algorithm provides excellent robustness against the signal steering vector mismatches, yields improved signal capture performance, has superior performance on SINR improvement, and enhances the array system performance under random perturbations in sensor parameters. The on-line implementation and significant SINR enhancement support the practicability of the proposed algorithm. The numerical experiments have been carried out to demonstrate the superiority of the proposed algorithm on beampattern control and output SINR enhancement compared with linearly constrained LSCMA.     

Design of a systolic-pipelined architecture for real-time enhancement of color video stream based on an illuminance-reflectance model

A high performance digital architecture for the implementation of a nonlinear image enhancement technique is proposed in this paper. The image enhancement is based on an illuminance-reflectance model which improves the visual quality of digital images and video captured under insufficient or non-uniform lighting conditions. The algorithm shows robust performance with appropriate dynamic range compression, good contrast, accurate and consistent color rendition. The algorithm contains a large number of complex computations and thus it requires specialized hardware implementation for real-time applications. Systolic, pipelined and parallel design techniques are utilized effectively in the proposed FPGA-based architectural design to achieve real-time performance. Approximation techniques are used in the hardware algorithmic design to achieve high throughput. The video enhancement system is implemented using Xilinx's multimedia development board that contains a VirtexII-X2000 FPGA and it is capable of processing approximately 63 Mega-pixels (Mpixels) per second.     

基于概率耦合的双直接判决先验信噪比估计算法

直接判决（DD,Decision-Directed）算法结构简单、音乐噪声抑制能力较好,是当前语音增强领域最为常用的先验信噪比估计方法.但该算法对于滑动因子的选取数值较为敏感,且估计性能要受到时延问题的限定.本文首先采用实际的语音和噪声数据,根据音乐噪声残留及输出语音失真两方面的评测标准对DD算法中滑动因子的取值问题进行了研究,通过数据分析给出了其较为明确的上下边界值;然后基于语音及噪声信号的复高斯分布模型,采用软判决技术对两个具有不同滑动因子的DD算法进行概率耦合,提出了一种具有双DD结构的先验信噪比估计算法.该算法可以充分结合两个具有不同特性DD算法的优点,在音乐噪声抑制及限制语音失真等方面均获得了较为理想的输出效果.多种噪声背景及输入信噪比条件下的仿真结果表明,相对于目前流行的几种先验信噪比估计算法,本文提出算法具有更为优良的估计性能.     

Performance of linear MMSE multiuser detection combined with a standard IS-95 uplink

Current implementation of IS-95 based systems is performance limited due to the use of a “conventional” detection scheme, which is susceptive to inter-user interference. We focus on the uplink, and try to examine the performance enhancement achieved by a suboptimal linear multiuser MMSE pre-filter, applied in front of the “standard” detection mechanism. We demonstrate the limitations of this relatively simple approach, and the constellations in which it may show improved performance. This revised version was published online in July 2006 with corrections to the Cover Date.     

基于增益函数的线性预测语音增强算法的研究

增益函数估计的精确度直接决定了语音增强算法的性能,并且增益函数的估计依赖于先验信噪比估计算法.DD(Decision Directed)算法具有较低的计算复杂度和有效抑制音乐噪声的优点,是最常用的先验信噪比估计算法,但是DD算法具有语音失真严重的缺点.介绍了DD算法、MDD(Modified method)算法和线性预测增益函数算法,理论分析了各自性能的优缺点,并进行了实验验证.实验结果显示,增益函数的线性预测方法可以取得较好的语音增强性能.     

混沌密码及其在多媒体保密通信中应用的进展

该文回顾了过去混沌密码理论与应用的现状及存在的问题,并对其进行了综合评述。重点报道了近年来高维混沌密码及其在多媒体保密通信中的应用与硬件实现技术的进展,其中包括基本理论、设计方法、典型应用以及解决这些问题的思路。在混沌密码设计与安全性能评估方面,报道了以下几个方面的进展:基于反控制方法设计无简并高维混沌密码增强数字混沌的抗退化能力;无退化数字域混沌系统的设计;具有闭环反馈的有限精度高维混沌长周期序列流密码的多轮加密设计方案;高维混沌密码的安全性能评估。在多媒体保密通信中的应用与硬件实现方面,报道了针对手机,计算机,ARM, FPGA, DSP等手持设备所需不同应用业务、广域网和WIFI无线通信网传输的实时远程混沌保密通信应用环境和多位一体的应用平台进行优化融合,创建示范验证系统等若干技术实现问题的进展。该文试图推进国内外未来混沌密码理论及其应用的研究。     

UMTS security: system architecture and hardware implementation

Universal mobile telecommunication system (UMTS) has specified security mechanisms with extra features compared to the security mechanisms of previous mobile communication systems (GSM, DECT). A hardware implementation of the UMTS security mechanism is presented in this paper. The proposed VLSI system supports the Authentication and Key Agreement procedure (AKA), the data confidentiality procedure, and the integrity protection procedure. The AKA procedure is based on RIJNDAEL Block Cipher. An efficient RIJNDAEL architecture is proposed in order to minimize the usage of hardware resources. The proposed implementation performs the AKA procedure within 76 µs comparing with the 500 ms that UMTS specifies. The data confidentiality and the integrity protection is based on KASUMI Block Cipher. The proposed KASUMI architecture reduces the hardware resources and power consumption. It uses feedback logic and positive‐negative edge‐triggered pipeline in order to make the critical path shorter, without increasing the execution latency. The S‐BOXes that are used from RIJNDAEL and KASUMI block ciphers have been implemented with combinational logic as well as with ROM blocks. Copyright © 2006 John Wiley & Sons, Ltd.     

基于组合代价函数的双模式盲均衡新算法

以常数模和判决引导准则设计的双模式盲均衡算法可显著提高均衡性能,目前已有双模式盲均衡算法均需设置切换参数且切换参数选择和设定缺乏理论依据.为解决双模式盲均衡算法中切换参数难以确定的问题,提出来一种组合代价函数的双模式盲均衡新算法.利用常数模和判决引导准则通过加权设计代价函数,在盲均衡器更新过程中自适应调节权值实现算法由常数模算法向判决引导算法的切换,避免了在双模式算法中设计切换参数,提高了算法的泛化性能.为克服常数模算法相位盲的缺点,在虚实分开改进的常数模算法基础上优化组合代价函数以及盲均衡器更新算法的设计,进一步提高了算法收敛性能.仿真结果证明,组合代价函数双模式盲均衡新算法可充分发挥常数模算法和判决引导算法的优点,具有更快的收敛速度和更小的稳态剩余误差.     

Theoretical analysis of a correlation attack based on convolutional codes

One general class of attacks on stream ciphers is correlation attacks. Most of previous results regarding performance of correlation attacks have been based entirely on simulations. We use random coding bounds for convolutional codes to give a theoretical analysis of a previously proposed correlation attack based on convolutional codes. The results from the theoretical derivation are verified by simulations.     

构造分支数为4的对合线性变换

扩散层是分组密码的一个重要组件,特别是SPN型结构的密码以及轮函数为SPN型的Feistel结构密码,都要用到一个非退化的线性变换作为其扩散层。好的分支数以及线性变换的对合性质对分组密码的扩散性以及实现效率都有很大的提高。本文基于循环移位和异或运算构造了三种线性变换。并证明了这三种线性变换是分支数为4的次最优的线性变换,同时在一定条件下,还证明了它们均是对合的线性变换。     

基于直接判决估计和预测估计的语音增强算法

对噪声环境下语音增强算法中的先验信噪比估计提出了一种新的估计算法。该算法结合了直接判决估计和预测估计方法,与传统的基于直接判决的先验信噪比估计算法相比较,当后验信噪比较大时,该算法减少了语音失真;当后验信噪比较小时,算法较明显地减少了音乐噪声。通过研究发现传统的直接判决方法就是该算法的一个特例,该算法可以通过一个权衡因子退化为传统的直接判决方法。实验结果也证实所提出的算法的优越性能。     

On channel estimation and sequence detection of interleaved codedsignals over frequency nonselective Rayleigh fading channels

Due to the receiver complexity introduced by interleaving, the implementation of maximum likelihood (IML) decoding of interleaved coded signals transmitted over frequency nonselective Rayleigh fading channels has been shown to be practically impossible. As an alternative, a two-stage receiver structure has been proposed, where the channel estimation and sequence decoding are done separately. The channel estimation issue in a two-stage receiver is examined in detail in this paper. It is shown that although an optimum (maximum a posteriori (MAP)) channel estimation is not possible in practice, it can be approached asymptotically by joint MAP estimation of the channel and the coded data sequence. The implementation of the joint MAP estimation is shown to be an ML sequence estimator followed by an minimum mean-square error (MMSE) channel estimator. Approximate fill sequence estimation using pilot symbol interpolation is also studied, and through computer simulations, its performance is compared to receivers using hit sequence estimation. The effect of decision delay (DD), prediction order, and pilot insertion rate (PIR) on the reduced complexity ML sequence estimation is investigated as well. Finally, a practical receiver is proposed that makes the best compromise among the error performance, receiver complexity, DD, and power (or bandwidth) expansion due to pilot insertion