查询词典 cipher in algorism

It is greatly efficient, because this overcomes the shortcoming of Eratosthenes algorism that need compare every natural number in the given range, This algorism can acquire all prime numbers between 1 and any given natural number m This article also has given the complexity of the algorism, and even if sift in the algorism were different, it will be...

这避免了传统Eratosthenes 筛法需要比较每个数的缺点，极大地提高了算法效率。该算法能用于求1至任意自然数m之间的所有素数。同时还给出了该算法的最多比较次数公式，即使用不同的筛子利用该公式也容易求得其最大比较次数。

Prime number ; distribution of prime ; divide exacdy ; sifting algorism of Eratosthenes ; algorism ; dynamic sifting algorism ; static sift algorism

素数；素数分布；整除； Eratosthenes筛法；算法；动态筛法；静态筛法

The symmetric algorithm is a traditional algorithm, it is easy and efficient, and so it is still being popular used. The stream cIPher and the block cIPher are two part of the symmetric algorithm. The symmetric algorithm uses the key to control the key stream generator, and then the generator produces a random stream. We can get the cIPher by xor the message and the random stream by bit. In the field of communication and code, the stream cIPher has always been the key cIPher of the military affairs and foreign affairs.

对称密码体制分为序列密码和分组密码两类，序列密码以密钥控制密钥流发生器，产生一随机序列，用这个随机序列和明文信息逐位异或，就得到密文，其加密单元为比特。

It must improve the commonly symmetrical key block cipher arithmetic for ensuring that the data length will not be increased after encryption: using forward shift bits mode in Triple DES with Two Keys; using cipher text stealing mode in RC5 with Cipher Block Chaining.

为保证加密后数据长度不变，应对常用的对称密钥分组密码算法以改进：双密钥三重DES加密采用向前挪位法，RC5密码分组链接加密采用密文窃取方式。

For example, if the two methods used are the Playfair cipher and simple columnar transposition, if transposition is used first, the Playfair cipher can still be attacked, because it takes each input letter to a limited number of substitutes; if the Playfair cipher is used first, multiple anagramming, although now much more difficult, is still possible because a text enciphered by Playfair still has digraph frequencies marked well enough to allow a correct match to be detected.

例如，如果这两种方法用的是playfair密码和简单的柱状移位，如果移位是用第一， playfair密码仍然可以被攻击，因为它需要每个输入信有限数量的代用品；如果playfair密码是用来首先，多重anagramming ，虽然现在困难得多，仍然有可能因为一个文本加密由playfair仍然有向图的频率明显做得不够好，让一个正确的匹配，以进行检测。

This paper presents an introduction of the mechanism and advantages of Playfair algorism,and provides a complete plan and program of C-language simulative fulfillment,which will make it more vivid and convenient for one to understand this algorism.

介绍了P layfair算法的原理及其优点，给出了用C语言模拟实现P layfair算法的完整思路和程序。为形象的了解此算法提供了最方便的途径

Since the ID3 algorism has obvious advantage on attribute screening, the algorism so as to get a simplified financial index system was modified in this paper.

利用决策树算法在筛选属性方面的优势，对传统ID3算法进行了改进，建立了一个精简的财务指标体系。

In the area of face detection, there is knowledge based method, feature based method and model matched method, in which we mainly introduce the Adoboost algorism and ASM algorism.

首先对人脸检测和跟踪技术进行综述，在此基础上，介绍了多种人脸检测和跟踪的方法，比较了它们的优缺点。

Global convergence strategy is combined to gauss-newton method that performs the virtue of insensitiveness to initial guess in iteration algorism, when applied to nonlinear least square estimation in target location, the algorism can approach the precise guess by iterations with the noise-polluted initial guess.

将全局收敛策略与牛顿法相结合，得到了对初值不敏感的迭代算法。将该算法应用于非线性最小二乘目标定位中，在初值受测量误差影响而估计不准的情况下，可以通过迭代得到精度更高的解。

Chapter 4 presents five design criteria of S-boxes of block ciphers, develops a method of constructing large S-box by use of algebraic group operation, proves the balance property of these large S-box, tests the strict avalanche and independence of avalanche variables properties of S-boxes in NEA cipher, analyses the nonlinearity and best linear approximation of the S-box, and finally defines the differential of input/output of S-boxes of this cipher and analyses the distribution of them.

第二部分即第三章，提出了一种新的分组密码类NEA(NEA-4A，NEA-8A，NEA-4B，NEA-8B)，完整地描述了该密码类的加解密过程和密钥协议；证明了NEA-4B和NEA-8B的完全对合性和没有不动点的性质；分析了该密码类的安全特征；具体地介绍了实现该类密码的途径；给出了NEA-4A的计算机C语言程序和样本数据。

This paper designs the communication system of radio telescope FAST.

针对500m口径球面射电望远镜FAST分布式控制系统的特点完成了其通信系统的设计。

Political sheep's step-by-step a large number of fossils unearthed in the county soil Ma Ali after rural village in the middle of sallow pelitic siltstone.

步氏和政羊化石大量出土于广河县阿力麻土乡后山村，产于灰黄色泥质粉砂岩中。