线宽增强因子对光反馈半导体激光器混沌信号生成随机数性能的影响

基于光反馈半导体激光器产生的宽带混沌信号作为物理熵源生成物理随机数已得到广泛研究.线宽增强因子的存在会导致半导体激光器出现大量不稳定动态特性,因此,本文着重研究半导体激光器的线宽增强因子对生成随机数性能的影响.数值仿真结果表明:随着线宽增强因子的增加,光反馈半导体激光器输出混沌信号的延时峰值逐渐减小、最大李雅普诺夫指数逐渐增大.基于不同线宽增强因子下产生的混沌信号提取随机数,并利用NIST SP 800-22软件对生成随机数的性能进行测试.测试结果表明,选取线宽增强因子较大的半导体激光器产生混沌信号作为物理熵源易于生成性能良好的随机数.     

基于复振幅场信息复用和RSA算法的非对称多幅图像认证方法

结合相位恢复和像素行、列循环移动置乱技术, 本文提出了一种基于复振幅场信息复用和RSA算法的非对称多幅图像认证方法, 通过菲涅耳域的相位恢复算法, 依次恢复并生成多幅图像各自所对应的输入平面的复振幅信息, 通过各自的行、列向量随机数对原始二值振幅模板进行行、列循环移动置乱操作来获得每幅图像的采样模板, 认证系统将多个复振幅场信息采样、叠加并空间复用, 同时, 行向量随机数和列向量随机数被RSA算法公钥编码成密文. 系统认证时, 认证方利用自己持有的私钥将密文解码成行向量随机数和列向量随机数, 通过行、列循环移动置乱变换后获得各自的采样模板, 合成的复振幅信息和采样模板等认证信息均放置在各自正确位置, 当认证系统被正确波长的平面波照射时, 在输出平面能获得输出图像, 通过计算、显示输出图像和对应认证图像的非线性相关系数峰值来判断认证是否成功.     

利用混沌激光脉冲在线实时产生7 Gbit/s物理随机数

提出了一种基于混沌激光的在线实时产生高速物理随机数的方法,通过对连续的混沌激光进行光釆样得到离散的混沌激光脉冲序列,利用差分比较器对混沌脉冲序列进行自延迟比较,在线实时输出高速物理随机数.并以光反馈半导体激光器这一典型混沌激光产生装置作为物理熵源,对所提方法进行了原理性实验论证,实现了实时速率为7 Gbit/s的物理随机数在线产生,可成功通过随机数行业测试标准(NIST SP 800-22).     

基于混沌激光的无后处理多位物理随机数高速产生技术研究

提出一种基于混沌激光的无后处理多位物理随机数高速提取方法.该方法在光域中利用锁模激光器作为光时钟,通过太赫兹光非对称解复用器完成对混沌激光的超低抖动光采样,无需射频时钟及后续逻辑处理过程的参与,经多位比较量化可直接产生优质物理随机数.并以光反馈半导体激光器这一典型的混沌激光产生装置作为熵源对所提方法进行了原理性实验论证.结果显示,光反馈半导体激光器产生的6 GHz混沌激光经5 GSa/s实时、低抖动光采样后,利用并行输出型多位比较器对所获混沌脉冲序列进行量化处理,选取最低有效位4位,可直接产生速率达20 Gb/s的随机数.该随机数速率由选取的量化结果最低有效位数和光采样率联合决定,而当前光采样率受限于所用混沌激光熵源的带宽.本文工作可为硬件上实现更高速物理随机数的实时、在线产生提供有力的技术和理论支撑.     

运动目标时空频信号变换与多维信息关联

提出了一种针对水中匀速直线运动目标的时空频信号变换方法。首先对接收信号作时频分析和频域波束形成,根据选定的目标航向对频率-方位-时间三维信号空间中的接收信号进行由基阵坐标系到目标坐标系的视在方位变换,使目标线谱信号由三维空间轨迹变换为变换域中对应平面切片上的二维轨迹,该切片由频率与方位信息联合构成的轴和时间轴构成。研究结果表明,该方法能够在变换后的信号空间中将目标线谱信号的三维轨迹转换为相应切片上的二维轨迹,相比三维信号空间更容易获得多维信息联合处理的信号处理增益。     

基于混沌激光产生1 Gbit/s的随机数

利用光反馈半导体激光器产生的混沌激光作为随机数发生器的物理熵源,通过8位 ADC将熵源信息转化为二进制码,并经后续差分运算处理改善其随机性,最终获得了1 Gbit/s的随机数.所产生的随机数通过了NIST Special Publication 800-22的全部测试项. 关键词： 混沌激光 随机数发生器 半导体激光器 模数转换     

一种基于非下采样Contourlet变换多聚焦图像融合算法

针对现有小波类图像融合算法的不足,提出了一种基于非下采样Contourlet变换多聚焦图像融合算法,并在Contourlet域中引入了局部区域可见度以及局部方向能量的概念.针对低频子带系数和各带通方向子带系数分别提出了基于局部区域可见度以及基于局部方向能量的系数选择方案.通过对多聚焦图像融合的仿真实验,表明该算法相对于传统的基于离散小波变换和离散小波框架变换融合算法能够有效减少有用信息的丢失以及虚假信息的引入,同时能够从源图像中提取更多的有用信息并注入到融合图像中, 得到更好视觉效果和更优量化指标的融合图像.     

水下线谱噪声源识别的波束域时频分析方法研究

从联合空时频三维信息从发, 提出了波束域时频分析识别水下运动航行器低频线谱噪声源位置的方法. 首先, 利用小孔径圆环阵的超指向性波束形成, 将各线谱噪声源匀速通过正横位置附近时产生的多普勒信号在时域上分离. 其次, 分别使用伪Wigner-Ville分布和调频小波变换两种时频分析方法对波束输出的信号进行处理, 得到各噪声源信号的时频图像. 最后, 转换时间坐标到空间并参考配置信标, 即可识别低频线谱噪声源在水下航行器上的位置. 该方法解决了阵列识别水下低频噪声源的孔径受限问题, 同时对处理同频相干噪声源也适用. 仿真试验结果表明: 两种波束域时频分析方法都能较精确地识别低频线谱噪声源的位置; 在测量系统信息的配合下, 波束域调频小波变换的识别效果更优.     

基于激光器阵列后处理的混沌熵源获取高品质随机数

本文提出采用可集成的激光器阵列后处理光反馈半导体激光器的输出,进而获得无时延特征的优质混沌熵源,进一步获取高速高品质随机数序列.方案中采用常规的8位模数转换采样量化和多位最低有效位异或提取处理,采用国际公认的随机数行业测试标准(NIST SP 800-22)来检验产生的序列.结果表明,通过激光器阵列后处理的混沌熵源所获取的随机数序列具有均匀的分布特性,散点图无明显图案,可以成功通过NIST SP 800-22的全部测试.另外,基于激光器阵列的可扩展性,本方案可以拓展为可实现同时产生多路并行的高速高品质随机数发生器.     

基于非线性级联傅里叶变换的光学Hash函数构造

提出一种基于非线性级联傅里叶变换的光学Hash函数的构造方法.此方法分为两轮单向加密过程,在第一轮中,先将待处理的数字信息以512bit作为数据块编码,将整个数字信息整分成若干个"8×8的256阶灰度图像"(信息平面),然后在光电混合系统中对上述信息平面组做非线性级联傅里叶变换得到一个数值矩阵,对其进行扩展后得到4个信息平面,再对它们做非线性级联傅里叶变换得到64bit的Hash值(hash1);在第二轮中,先将原始信息平面中的每个数值循环左移4位,构造出相应的辅助信息平面组,然后对其做与第一轮相同的单向加密操作,得到hash2,将其与之前生成的hash1组合起来构成最终128bit的Hash值(hash).同时,本文提出采用雪崩效应系数(AEC)作为评价光学Hash函数性能的参数,理论分析和仿真实验均表明,该方法构造的光学Hash函数具有很好的抗碰撞性和良好的雪崩效应.     

Image encryption using random sequence generated from generalized information domain

A novel image encryption method based on the random sequence generated from the generalized information domain and permutation–diffusion architecture is proposed. The random sequence is generated by reconstruction from the generalized information file and discrete trajectory extraction from the data stream. The trajectory address sequence is used to generate a P-box to shuffle the plain image while random sequences are treated as keystreams. A new factor called drift factor is employed to accelerate and enhance the performance of the random sequence generator. An initial value is introduced to make the encryption method an approximately one-time pad. Experimental results show that the random sequences pass the NIST statistical test with a high ratio and extensive analysis demonstrates that the new encryption scheme has superior security.     

Consideration for Affects of an XOR in a Random Number Generator Using Ring Oscillators

A cloud service to offer entropy has been paid much attention to. As one of the entropy sources, a physical random number generator is used as a true random number generator, relying on its irreproducibility. This paper focuses on a physical random number generator using a field-programmable gate array as an entropy source by employing ring oscillator circuits as a representative true random number generator. This paper investigates the effects of an XOR gate in the oscillation circuit by observing the output signal period. It aims to reveal the relationship between inputs and the output through the XOR gate in the target generator. The authors conduct two experiments to consider the relevance. It is confirmed that combining two ring oscillators with an XOR gate increases the complexity of the output cycle. In addition, verification using state transitions showed that the probability of the state transitions was evenly distributed by increasing the number of ring oscillator circuits.     

A universal algorithm to generate pseudo-random numbers based on uniform mapping as homeomorphism

A specific uniform map is constructed as a homeomorphism mapping chaotic time series into [0,1] to obtain sequences of standard uniform distribution. With the uniform map, a chaotic orbit and a sequence orbit obtained are topologically equivalent to each other so the map can preserve the most dynamic properties of chaotic systems such as permutation entropy. Based on the uniform map, a universal algorithm to generate pseudo random numbers is proposed and the pseudo random series is tested to follow the standard 0-1 random distribution both theoretically and experimentally. The algorithm is not complex, which does not impose high requirement on computer hard ware and thus computation speed is fast. The method not only extends the parameter spaces but also avoids the drawback of small function space caused by constraints on chaotic maps used to generate pseudo random numbers. The algorithm can be applied to any chaotic system and can produce pseudo random sequence of high quality, thus can be a good universal pseudo random number generator.     

Novel image encryption algorithm based on multiple-parameter discrete fractional random transform

A new method of digital image encryption is presented by utilizing a new multiple-parameter discrete fractional random transform. Image encryption and decryption are performed based on the index additivity and multiple parameters of the multiple-parameter fractional random transform. The plaintext and ciphertext are respectively in the spatial domain and in the fractional domain determined by the encryption keys. The proposed algorithm can resist statistic analyses effectively. The computer simulation results show that the proposed encryption algorithm is sensitive to the multiple keys, and that it has considerable robustness, noise immunity and security.     

基于两正交互耦1550nm垂直腔面发射激光器获取多路随机数

提出将正交互耦1550 nm垂直腔面发射激光器(1550 nm-VCSEL)在优化条件下输出的多路平均功率可比拟、延时特征(TDS)得到有效抑制的混沌信号作为混沌熵源,经8位模数转换器(ADC)量化和最低有效位(m-LSB)后续处理获取多路物理随机数的方案,并研究了系统参量对最终获取的比特序列随机性的影响.首先,基于VCSEL的自旋反转模型分析耦合强度和频率失谐对两个正交互耦合1550 nm-VCSEL输出动力学的影响,初步确定利用该系统产生四路平均功率可比拟、TDS得到抑制的混沌信号所需的耦合强度和频率失谐优化范围;在此基础上,选择一个耦合强度值,利用处于优化范围内的不同频率失谐下获取的四路混沌信号作为熵源,经8位ADC量化和m-LSB后续处理得到最终的比特序列;最后,采用NIST Special Publication800-22统计测试套件对获取的最终比特序列的随机性能进行测试,确定了同时获取四路高质量随机数所需的参数范围.     

脊小波变换域模糊自适应图像增强算法

提出了基于脊小波(ridgelet)变换域的模糊自适应图像增强算法,利用脊小波变换在表示图像线性奇异边缘时具有独特的优越性,达到突出边缘和抑制噪声的目的。利用频域内傅里叶投影变换定理,提出优化有限拉东(Radon)变换系数顺序的方法,使得拉东变换后图像的折回现象得到改善;利用广义模糊集合概念和最大模糊熵原理,提出一种自适应设置模糊增强函数方法,使得增强后的图像在抑制噪声、增强特征方面达到较好折衷。通过模拟实验显示,该算法优于传统的增强方式,在低信噪比情况(2.5~5.5 dB)下,其边缘检测概率大于二维小波增强方式约50%。应用于含有局部线形裂纹的路面病害图像的增强,可以将裂纹信号基本增强出来,且对路面上离散的油滴、石子等点噪声抑制较好。     

Image displacement based on phase-encoded reference joint fractional transform correlator

In order to utilize the space of an input plane efficiently and make the optical structure more flexible, an image displacement measurement based on phase-encoded reference joint fractional transform correlator (PER-JFrTC) is proposed. We use a random phase mask to encode the reference image and overlay it with the target image forming the input image. Joint power spectrum (JPS) of the input image is obtained by Fourier transform and the resultant is encoded by the same phase mask. Then a fractional Fourier transform with an order p is applied to the phase-encoded JPS (PJPS), resulting in a correlation output with a sharp cross-correlation peak, which includes the displacement information between the reference and the target image. Contrast to displacement measurement based on traditional joint transform correlator (JTC), PER-JFrTC can use the space of the input plane efficiently and reduces the influence of the auto-correlation. Also the position of cross-correlation peak can be fixed arbitrarily according to the fractional order p as well as the optical set-up can be more flexible and easier to implement. Results based on digital computation show that PER-JFrTC could detect the displacement accurately and verify our proposal. A possible optical set-up is suggested.     

Novel image fusion method based on discrete fractional random transform

We introduce a new spectrum transform into the image fusion field and propose a novel fusion method based on discrete fractional random transform （DFRNT）. In DFRNT domain, high amplitude spectrum （HAS） and low amplitude spectrum （LAS） components carry different information of original images. For different fusion goals, different fusion rules can be adopted in HAS and LAS components, respectively. The proposed method is applied to fuse real multi-spectral （MS） and panchromatic （Pan） images. The fused image is observed to preserve both spectral information of MS and spatial information of Pan. Spectrum distribution of DFRNT is random and uniform, which guarantees that good information is reserved.     

True Random Number Generator Realized by Extracting Entropy from a Negative-Inductance Superconducting Quantum Interference Device

A new type of superconductive true random number generator(TRNG) based on a negative-inductance superconducting quantum interference device(nSQUID) is proposed. The entropy harnessed to generate random numbers comes from the phenomenon of symmetry breaking in the nSQUID. The experimental circuit is fabricated by the Nb-based lift-off process. Low-temperature tests of the circuit verify the basic function of the proposed TRNG.The frequency characteristics of the TRNG have been analyzed by simulation. The generation rate of random numbers is expected to achieve hundreds of megahertz to tens of gigahertz.