维吉尼亚密码java代码实现根据密钥长度计算IC值过程

package cn.longxuzi;

import java.util.Scanner;

import org.junit.Test;

public class ICUtils {

/**

* @author龙须子(XuziLong)

* @param null

* @return String [][]devideCipherText

* @Date 2013-11-20 PM 19:00

*/

public String[][] devideCipherText() {

// 根据密钥长度将密文分解成密钥长度个小组

String[][] str;

System.out.println("请输入密文字符串(以回车键结束)");

Scanner sc = new Scanner(System.in);

String ciphertext = sc.nextLine().toUpperCase().trim();

System.out.println("请输入密钥长度(以回车键结束)");

int keyLength = sc.nextInt();

// 计算每一组最多有多少个字母

int amount = 0;

if (ciphertext.length() % keyLength == 0) {

amount = ciphertext.length() / keyLength;

} else {

amount = (ciphertext.length() / keyLength) + 1;

}

// 初始化存储分开组的密文的字符串数组

str = new String[keyLength][amount];

int flag = 0, i = 0;

for (int j = 0; j < keyLength; j++) {

for (int k = 0; k < amount; k++) {

if (i + 1 > ciphertext.length()) {

break;

}

str[j][k] = ciphertext.substring(i, i + 1);

i = i + keyLength;

}

i = flag + 1;

flag++;

}

return str;

}

/**

* @author龙须子(XuziLong)

* @param String

*            [][]

* @return double Every[]IC value

* @Date 2013-11-20 PM 19:23

*/

public double[] getIC(String[][] str) {

// 计算每一小组密文的IC值

double[] IC = new double[str.length];

char[] letter = { 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77,

78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90 };// 创建字母表数组

int[][] sum = new int[str.length][letter.length];// 创建存放每个密文小组中每个字母出现次数的数组

int count = 0;// 计数器

for (int i = 0; i < str.length; i++) {

for (int j = 0; j < letter.length; j++) {

for (int k = 0; k < str[0].length; k++) {

if (String.valueOf(letter[j]).toUpperCase()

.equals(str[i][k])) {

count++;

}

}

sum[i][j] = count;

count = 0;

}

}

double[] result = new double[IC.length];

for (int j = 0; j < str.length; j++) {

for (int k = 0; k < letter.length; k++) {

if (sum[j][k] != 0) {

result[j] += sum[j][k] * (sum[j][k] - 1);

}

}

}

double N = (double) (str.length * str[0].length);

for (int j = 0; j < IC.length; j++) {

IC[j] = (double) (result[j] / (N * (N - 1)));

}

return IC;

}

/**

* @author龙须子(XuziLong)

* @param double[]IC

* @return double average []IC

* @Date 2013-11-21 PM 19:23

*/

public double getAverageIC(double[] IC) {

// 计算所有密文小组IC的平均值

double result = 0;

for (int i = 0; i < IC.length; i++) {

result += IC[i];

}

return result / (double) (IC.length);

}

//以下是求每一个密文小组IC值及分组情况的测试代码

@Test

public void tests() {

while (true) {

ICUtils tes = new ICUtils();

String[][] str = tes.devideCipherText();

for (int i = 0; i < str.length; i++) {

System.out.print("第" + (i + 1) + "小组的密文字母串为：");

for (int k = 0; k < str[0].length; k++) {

if (str[i][k] == null) {

str[i][k] = "";

}

System.out.print(str[i][k]);

}

System.out.println();

}

double[] ic = tes.getIC(str);

for (int j = 0; j < ic.length; j++) {

System.out.println("该小组密文的IC值为：" + ic[j]);

}

System.out.println("本次分组中IC的平均值为："

+ tes.getAverageIC(tes.getIC(str)));

}

}

}