使用描述的使用两个凯撒密码密钥的算法加密以下短语，其中 key1 = 8 和 key2 = 21。
中午，戴上帽子，在会议室参加一场惊喜派对。大声喊叫！
加密后的字符串是什么？
（注意：您的加密字符串应保留空格和标点符号。）
原始输入是
中午，戴上帽子，在会议室参加一场惊喜派对。大声喊叫！
想要的结果是
io iwjv jz dv bcm kjvammmikz mwju edbc twpz pvb wi awm v ncmxmqnm xvzog。 tmgttjcy！
我无法为这个问题编写正确的Java代码。请帮忙，非常感谢！
我的代码是
import edu.duke.*;
public class CaesarCipher {
public String encrypt(String input, int key1, int key2) {
//Make a StringBuilder with message (encrypted)
StringBuilder encrypted = new StringBuilder(input);
//Write down the alphabet
String checker = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
String alphabet = checker.toLowerCase();
//Compute the shifted alphabet
String shiftedAlphabet1 = alphabet.substring(key1)+
alphabet.substring(0,key1);
String shiftedAlphabet2 = alphabet.substring(key2) + alphabet.substring(0,key2);
//Count from 0 to < length of encrypted, (call it i)
for(int i = 0; i < encrypted.length(); i+=2) {
//Look at the ith character of encrypted (call it currChar)
char currChar1 = encrypted.charAt(i);
int j = i+1;
char currChar2 = encrypted.charAt(j);
//Find the index of currChar in the alphabet (call it idx)
int idx1 = alphabet.indexOf(currChar1);
int idx2 = alphabet.indexOf(currChar2);
//If currChar is in the alphabet
if(idx1 != -1){
//Get the idxth character of shiftedAlphabet (newChar)
char newChar1 = shiftedAlphabet1.charAt(idx1);
encrypted.setCharAt(i, newChar1);
char newChar2 = shiftedAlphabet2.charAt(idx2);
encrypted.setCharAt(j, newChar2);
}
//Replace the ith character of encrypted with newChar
}
//Otherwise: do nothing
}
//Your answer is the String inside of encrypted
return encrypted.toString();
}
public void testCaesar() {
int key1 = 8;
int key2 = 21;
FileResource fr = new FileResource();
String messagechecker = 'At noon be in the conference room with your hat on for a surprise party. YELL LOUD!';
String message = messagechecker.toLowerCase();
String encrypted = encrypt(message, key1, key2);
System.out.println(encrypted);
String decrypted = encrypt(encrypted, 26-key1,26-key2);
System.out.println(decrypted);
}
}
代码不处理要求：“（注意：您的加密字符串应保留空格和标点符号。）”，特别是字母表仅包含小写字母。您将需要处理从 0x20 到 0x7f 的所有字符代码。
对于“双”凯撒密码，创建一个子例程，对字符串执行单个凯撒密码，然后首先使用原始输入和第一个密钥调用该函数，然后再次使用该输出和第二个密钥调用该函数。
当 idx2 大于 for 循环的索引（即 j+1 > crypto.length()）时，我看到问题出现。要计算 idx2，您需要检查 i+1(j) 的大小。
if (i+1 < encrypted.length()) {
int j = i+1;
char ch2 = encrypted.charAt(j);
char currChar2 = Character.toLowerCase(ch2);
//Find the index of currChar in the alphabet (call it idx)
int idx2 = alphabet.indexOf(currChar2);
if (idx2 != -1) {
char newChar2 = shiftedAlphabet2.charAt(idx2);
//Replace the ith character of encrypted with newChar
encrypted.setCharAt(j, newChar2);
}
}
}
import java.util.Scanner;
public class caesarCipher {
/* This method is used to both encrypt and decrypt */
public static String encrypt(String input, int key1, int key2) {
int pos = -1, pos1 = -1;
String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; /* Take whole
alphabet as a string */
/* modify the encrypted string use string builder */
StringBuilder encrypted = new StringBuilder(input);
for (int i = 0; i < encrypted.length(); i++) {
/* take each character from the string */
char sample = encrypted.charAt(i);
/* We have to perform only with alphabet */
if (Character.isAlphabetic(sample)) {
/* check the position as key1 for even and key2 for odd position */
if (i % 2 == 0) {
/*
* if the character is uppercase nothing to do
* cause we take alphabet in total uppercase
*/
if (Character.isUpperCase(sample)) {
/* find the position of the character from the alphabet */
pos = alphabet.indexOf(sample);
/* set the position as key */
pos = (pos + key1) % 26;
/* find the letter with updated position from the alphabet */
char res = alphabet.charAt(pos);
/* modify it */
encrypted.setCharAt(i, res);
}
/* if the character is in lowercase */
else {
/* convert it to uppercase to find */
pos = alphabet.indexOf(Character.toUpperCase(sample));
pos = (pos + key1) % 26;
char res = alphabet.charAt(pos);
/* convert the desired output in lowercase then modify it */
encrypted.setCharAt(i, Character.toLowerCase(res));
}
pos = -1;
}
/* same above procedure in case of odd position */
else {
if (Character.isUpperCase(sample)) {
pos1 = alphabet.indexOf(sample);
pos1 = (pos1 + key2) % 26;
char res1 = alphabet.charAt(pos1);
encrypted.setCharAt(i, res1);
} else {
pos1 = alphabet.indexOf(Character.toUpperCase(sample));
pos1 = (pos1 + key2) % 26;
char res1 = alphabet.charAt(pos1);
encrypted.setCharAt(i, Character.toLowerCase(res1));
}
pos1 = -1;
}
}
}
return encrypted.toString();
}
public static void main(String[] args) {
// TODO Auto-generated method stub
Scanner sc = new Scanner(System.in);
System.out.println("Enter the string:");
String input = sc.nextLine();
System.out.println("Enter the key1:");
int key1 = sc.nextInt();
System.out.println("Enter the key2:");
int key2 = sc.nextInt();
/*
* for both encryt and decrypt use the same method but for decrypt key will be
* 26-key
*/
String e = encrypt(input, key1, key2);
System.out.println("...........After encryption...........\n" + e);
String d = encrypt(e, (26 - key1), (26 - key2));
System.out.println("...........After decryption...........\n" + d);
}
}
/* Compile and enjoy */
//这是完整的正确答案
public class CaesarCipher {
//this method to encrypt a messgae using a key
String encrypt (String input, int key){
// convert the original message to temp upper case letters
String input2 = input.toUpperCase();
// using string builder rather than normal string
StringBuilder sb= new StringBuilder(input2);
// default alphabet
String alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
// shiftted alphabet
String shifttedAlphabet= alphabet.substring(key)+alphabet.substring(0,key);
// iterating over the original message to get each char and then getting its index
// then getting the equilvent char in the shiftted alphabet
for (int i = 0; i <sb.length();i++){
char currentChar = sb.charAt(i);
int currentIndex = alphabet.indexOf(currentChar);
if (currentIndex != -1){
char shifttedChar = shifttedAlphabet.charAt(currentIndex);
sb.setCharAt(i,shifttedChar);
}
}
// converting the builder string to a normal string
String encrypted = sb.toString();
// getting every char to its normal case even lower or upper
for (int i =0 ;i < input.length(); i ++){
boolean upper = Character.isUpperCase(input.charAt(i));
if(upper){sb.setCharAt(i,Character.toUpperCase(encrypted.charAt(i)));}
else {sb.setCharAt(i,Character.toLowerCase(encrypted.charAt(i)));}
}
// restting the encrypted message after editting to the lower nad upper case state
encrypted = sb.toString();
// returning the encrypted string
return encrypted;
}
// this method to encrypt using two keys
String encryptTwoKeys (String input ,int key1 , int key2){
String encryptedKey1= encrypt (input, key1);
String encryptedKey2= encrypt (input, key2);
StringBuilder finalEncrypted = new StringBuilder (input);
for (int i = 0 ; i <encryptedKey1.length();i +=2){
char currentChar = encryptedKey1.charAt(i);
finalEncrypted.replace(i, i+1,String.valueOf(currentChar));
}
for (int i = 1 ; i <encryptedKey2.length();i +=2){
char currentChar = encryptedKey2.charAt(i);
finalEncrypted.replace(i, i+1,String.valueOf(currentChar));
}
return finalEncrypted.toString();
}
void testEncryptTwoKeys(){
String encrypted = encryptTwoKeys("At noon be in the conference room with your hat on for a surprise party. YELL LOUD!", 8, 21);
System.out.println (encrypted);
String decrypted = encryptTwoKeys(encrypted, 26-8, 26-21);
System.out.println (decrypted);
}
void testEncrypt(){
FileResource fr = new FileResource();
String message = fr.asString();
String encrypted = encrypt(message, 15);
System.out.println("key is " +15+ "\n" + encrypted);
}
}