使用两个Caesar Cipher密钥描述的算法加密以下短语，key1 = 8，key2 = 21.
中午在会议室里戴着帽子参加一个惊喜派对。 YELL LOUD！
什么是加密字符串？
（注意：您的加密字符串应保留间距和标点符号。）
原始输入是
中午在会议室里戴着帽子参加一个惊喜派对。 YELL LOUD！
期望的结果是
io iwjv jz dv bcm kjvammmikz mwju edbc twpz pvb wi awm v ncmxmqnm xvzog。 tmgt tjcy！
我无法为此问题编写正确的Java代码。请帮助，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);
}
}
答案 0 :(得分：0)
要求：“（注意：您的加密字符串应保留间距和标点符号。）”不由代码处理，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“double”Caesar Cipher创建一个子程序，在字符串上执行单个Caesar Cipher，然后首先使用原始输入和第一个键调用该函数，然后再使用该输出和第二个键调用该函数。
答案 1 :(得分：0)
我看到当idx2大于for循环的索引时出现问题（即j + 1＆gt; encrypted.length（））。要计算idx2，你需要检查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);
}
}
}
答案 2 :(得分：0)
//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);
// itterating around 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);
}
}
答案 3 :(得分：0)
import edu.duke.*;
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);
// itterating around 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;
}`enter code here`
// 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("Can you imagine life WITHOUT the internet AND computers in your pocket?", 21,8 );
System.out.println (encrypted);
String decrypted = encryptTwoKeys(encrypted, 26-21, 26-8);
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);
}
}