Java版 凯撒密码 加密、解密、暴力破解

用Java实现凯撒密码的 ‘加密’ 和 ‘解密’ 工作

代码实现如下：

代码片

package com.hellow.demo;import java.util.Scanner;// 凯撒密码public class Caesar {public static void main(String[] args) {int tpm;System.out.println("1.加密 2.解密 3.暴力破解\n 请选择模式：");Scanner sc = new Scanner(System.in);tpm = sc.nextInt();if (tpm == 1) {System.out.println("请输入明文:");Scanner sc1 = new Scanner(System.in);String s = sc1.nextLine();System.out.println("请输入密钥:");Scanner sc2 = new Scanner(System.in);int key = sc2.nextInt();//调用加密函数Encryption(s, key);} else if (tpm == 2) {System.out.println("请输入密文:");Scanner sc1 = new Scanner(System.in);String pwd = sc1.nextLine();System.out.println("请输入密钥:");Scanner sc2 = new Scanner(System.in);int key = sc2.nextInt();//调用解密函数Decrypt(pwd, key);} else if (tpm == 3) {System.out.println("请输入密文:");Scanner sc1 = new Scanner(System.in);String pwd = sc1.nextLine();//调用解密函数for (int i = 1; i <= 26; i++) {int key = i;Decrypt_attack(pwd, key);System.out.println("(密钥: " + key + ")\n");}} else {System.out.println("模式选择错误");}System.out.println("end");}//加密函数 Encryptionpublic static void Encryption(String str, int n) {String string = "";for (int i = 0; i < str.length(); i++) {char c = str.charAt(i);if (c >= 'a' && c <= 'z') {c += n % 26;if (c < 'a') {c += 26;}if (c > 'z') {c -= 26;}} else if (c >= 'A' && c <= 'Z') {c += n % 26;if (c < 'A') {c += 26;}if (c > 'Z') {c -= 26;}}string += c;}System.out.println(string);}//解密函数 Decryptpublic static void Decrypt(String str, int n) {// int k=Integer.parseInt("-"+n);String string = "";for (int i = 0; i < str.length(); i++) {char c = str.charAt(i);if (c >= 'a' && c <= 'z') {c -= n % 26;if (c < 'a') {c += 26;}if (c > 'z') {c -= 26;}} else if (c >= 'A' && c <= 'Z') {c -= n % 26;if (c < 'A') {c += 26;}if (c > 'Z') {c -= 26;}}string += c;}System.out.println(string);}//暴力破解函数 Decrypt_attackpublic static void Decrypt_attack(String str, int n) {// int k=Integer.parseInt("-"+n);String string = "";for (int i = 0; i < str.length(); i++) {char c = str.charAt(i);if (c >= 'a' && c <= 'z') {c -= n % 26;if (c < 'a') {c += 26;}if (c > 'z') {c -= 26;}} else if (c >= 'A' && c <= 'Z') {c -= n % 26;if (c < 'A') {c += 26;}if (c > 'Z') {c -= 26;}}string += c;}System.out.println(string);// hellow// khoorz// 3// see you tomorrow// vhh brx wrpruurz// 3// 密文: PELCGBTENCUL// 真实密钥：13// 明文: CRYPTOGRAPHY (n.密码学)}}