信息计算2019级2班15号陈周易

陈周易 · 发表于 2022-5-3 16:35:29

慕课截图

陈周易 · 发表于 2022-5-6 16:05:54

package secret;
public class node {
private double p;// 记录概率
private char alpha;// 记录对应的字母
public node(double p, char alpha) {
this.p = p;
this.alpha = alpha;
}
public void setp(double p) {
this.p = p;
}
public void setalpha(char a) {
this.alpha = a;
}
public double getp() {
return p;
}
public char getalpha() {
return alpha;
}

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陈周易 · 发表于 2022-5-6 16:07:00

package secret;
import java.math.BigInteger;
public class Prime {
public boolean sushu(double n) {
// 判断素数
boolean isPrime = true;
// 如果n大于2 继续判断否则 isPrime的值不变 2素数
if (n > 2) {
// 如果n是大于2的偶数认定不是素数修改变量值为false
if (n % 2 == 0) {
isPrime = false;
} else {
for (int i = 3; i <= (int) Math.sqrt(n); i += 2) {
if (n % i == 0) {
isPrime = false;
break;
}
}
}
}
return isPrime;
}
private static final BigInteger ZERO = BigInteger.ZERO;
private static final BigInteger ONE = BigInteger.ONE;
private static final BigInteger TWO = new BigInteger("2");
private static final int ERR_VAL = 100;
public BigInteger nextPrime(BigInteger start) {
// 产生一个比给定大整数 start 大的素数
if (isEven(start))
start = start.add(ONE);
else
start = start.add(TWO);
if (start.isProbablePrime(ERR_VAL))
return (start);
else
return (nextPrime(start));
}
private static boolean isEven(BigInteger n) {
// 测试一个大整数是否为偶数
return (n.mod(TWO).equals(ZERO));
}
public BigInteger bigRandom(int numDigits) {
// 产生一个随机大整数，各位上的数字都是随机产生的，首位不为 0
StringBuffer s = new StringBuffer("");
for (int i = 0; i < numDigits; i++)
if (i == 0)
s.append(randomDigit(false));
else
s.append(randomDigit(true));
return (new BigInteger(s.toString()));
}
private StringBuffer randomDigit(boolean isZeroOK) {
// 产生一个随机的数字（字符串形式的）
int index;
if (isZeroOK)
index = (int) Math.floor(Math.random() * 10);
else
index = 1 + (int) Math.floor(Math.random() * 9);
return (digits[index]);
}
private static StringBuffer[] digits = { new StringBuffer("0"),
new StringBuffer("1"), new StringBuffer("2"),
new StringBuffer("3"), new StringBuffer("4"),
new StringBuffer("5"), new StringBuffer("6"),
new StringBuffer("7"), new StringBuffer("8"), new StringBuffer("9") };
public static void main(String[] args) {
}
}

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陈周易 · 发表于 2022-5-6 16:07:29

package secret;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Scanner;
public class RSA {
static BigInteger x, y;
public static boolean fun(BigInteger x, BigInteger y) {
BigInteger t;
while (!(y.equals(new BigInteger("0")))) {
t = x;
x = y;
y = t.mod(y);
}
if (x.equals(new BigInteger("1")))
return false;
else
return true;
}
public static BigInteger siyue(BigInteger a, BigInteger b) {
BigInteger temp;
if (b.equals(new BigInteger("0"))) {
x = new BigInteger("1");
y = new BigInteger("0");
return x;
}
siyue(b, a.mod(b));
temp = x;
x = y;
y = temp.subtract((a.divide(b).multiply(y)));
return x;
}
public static double entropy(String mess) {
ArrayList<node> jieguo = new ArrayList<node>();
jieguo.clear();
double num = mess.length();
for (int i = 0; i < num; i++) {
boolean flag_exit = true;
for (int j = 0; j < jieguo.size(); j++) {
if (jieguo.get(j).getalpha() == mess.charAt(i)) {
flag_exit = false;
jieguo.get(j).setp(jieguo.get(j).getp() + 1 / num);
}
}
if (flag_exit)
jieguo.add(new node(1 / num, mess.charAt(i)));
}
/** 计算熵 */
double entropy = 0;
for (int i = 0; i < jieguo.size(); i++) {
double p1 = jieguo.get(i).getp();
entropy += (-p1 * (Math.log(p1) / Math.log(2)));
}
return entropy;
}
public static void main(String[] args) {
BigInteger p = null;
BigInteger e, d, n, t, c;
BigInteger q = null;
for (int i = 0; i < 2; i++) {
int numDigits;
Prime pri = new Prime();
try {
numDigits = Integer.parseInt("15");
} catch (Exception e1) {
numDigits = 128;
}
BigInteger start = pri.bigRandom(numDigits);
BigInteger big = pri.nextPrime(start);
if (i == 0)
p = big;
else
q = big;
}
Scanner input = new Scanner(System.in);
n = p.multiply(q);
t = p.subtract(new BigInteger("1")).multiply(
q.subtract(new BigInteger("1")));
int numDigits;
Prime pri = new Prime();
try {
numDigits = Integer.parseInt("15");
} catch (Exception e1) {
numDigits = 128;
}
BigInteger start = pri.bigRandom(numDigits);
BigInteger big = pri.nextPrime(start);
e = big;
while (e.compareTo(t) == 1 || fun(e, t)) {
System.out.println("e不合要求，请重新产生" + (e.compareTo(t) == 1)
+ fun(e, t));
pri = new Prime();
try {
numDigits = Integer.parseInt("15");
} catch (Exception e1) {
numDigits = 128;
}
start = pri.bigRandom(numDigits);
big = pri.nextPrime(start);
e = big;
}
// 求出私钥d
d = siyue(e, t);
System.out.println("由计算机随机产生2个素数p,q，分别如下:");
System.out.println(p);
System.out.println(q);
System.out.println("计算得到的n:");
System.out.println(n);
System.out.println("计算得到的t:");
System.out.println(t);
System.out.println("随机产生的公钥：");
System.out.println(e);
System.out.println("由扩展的欧几里德算法求得私钥：");
System.out.println(d);
while (true) {
System.out.println("请输入明文：");
String mess = input.nextLine();
//
BigInteger m = new BigInteger(mess.getBytes());// 把字串转成一个BigInteger对象
System.out.println("明文的整数表示形式：" + m);
/** 调用函数计算信息，统计信息 */
mess = m.toString();
c = m.modPow(e, n);// JAVA中的方法
System.out.println("密文的整数表示形式：" + c);
System.out.println("密文的字符串表示形式：" + new String(c.toByteArray()));
m = c.modPow(d, n);
String str = new String(m.toByteArray());// 把返回的结果还原成一个字串
System.out.println("解密得到明文为：" + str);
}
}
}

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陈周易 · 发表于 2022-5-6 16:08:34

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信息计算2019级2班15号陈周易

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