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)));
}
}
}