Question

作业2：两把钥匙

编写一个具有一个名为input的String参数的decrypt方法。此方法返回一个String，它是使用与此CaesarCipherTwo对象关联的key1和key2解密的加密String。您可能希望向该类添加更多私有字段。

有人可以帮我吗？我对如何为解密方法编写代码没有任何想法。我认为它应该有一个return语句，我有两个。 “与CaesarCipherTwo对象相关联”在如何编写代码方面意味着什么？

这就是我已经拥有的。欢迎提出任何建议：

import edu.duke.*;

public class CaesarCipherTwoKeys {
    private String alphabetLower;
    private String alphabetUpper;
    private String shiftedAlphabetLower1;
    private String shiftedAlphabetUpper1;
    private String shiftedAlphabetLower2;
    private String shiftedAlphabetUpper2;
    private int mainKey1;
    private int mainKey2;
    public CaesarCipherTwoKeys(int key1, int key2) {
        alphabetLower = "abcdefghijklmnopqrstuvwxyz";
        alphabetUpper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        shiftedAlphabetLower1 = alphabetLower.substring(key1) + alphabetLower.substring(0,key1);
        shiftedAlphabetUpper1 = alphabetUpper.substring(key1) + alphabetUpper.substring(0,key1);
        shiftedAlphabetLower2 = alphabetLower.substring(key2) + alphabetLower.substring(0,key2);
        shiftedAlphabetUpper2 = alphabetUpper.substring(key2) + alphabetUpper.substring(0,key2);
        mainKey1 = key1;
        mainKey2 = key2;
    }
    public String encrypt(String input) {
        StringBuilder encryptedInput = new StringBuilder(input);
        OOCaesarCipher oocc1 = new OOCaesarCipher(mainKey1);
        OOCaesarCipher oocc2 = new OOCaesarCipher(mainKey2);

        for (int index=0; index < input.length(); index++) {
            if (index % 2 == 0 || index == 0) {
                encryptedInput.replace(index,index+1,oocc1.encrypt(input.substring(index,index+1)));
            }
            else {
                encryptedInput.replace(index,index+1,oocc2.encrypt(input.substring(index,index+1)));
            }
        }
        return encryptedInput.toString();
    }
    public String decrypt(String input) {
        OOCaesarCipher oocc1 = new OOCaesarCipher(26-mainKey1);
        OOCaesarCipher oocc2 = new OOCaesarCipher(26-mainKey2);
        return oocc1.encrypt(input);
        return oocc2.encrypt(input);

    }
}

以下是上述代码中引用的OOCC类：

导入edu.duke。*;

public class OOCaesarCipher {
    private String alphabetLower;
    private String alphabetUpper;
    private String shiftedAlphabetLower;
    private String shiftedAlphabetUpper;
    private int mainKey;
    public OOCaesarCipher(int key) {
        alphabetLower = "abcdefghijklmnopqrstuvwxyz";
        alphabetUpper = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";
        shiftedAlphabetLower = alphabetLower.substring(key) + alphabetLower.substring(0,key);
        shiftedAlphabetUpper = alphabetUpper.substring(key) + alphabetUpper.substring(0,key);
        mainKey = key;
    }
    public String encrypt(String input) {
        StringBuilder encrypted = new StringBuilder(input);
        for (int index=0; index < encrypted.length(); index++) {
            Character currChar = encrypted.charAt(index);
            int currentIndex = 0;

            if (Character.isLowerCase(currChar)) {
                currentIndex = alphabetLower.indexOf(currChar);
            }
            else {
                currentIndex = alphabetUpper.indexOf(currChar);
            }

            if (currentIndex != -1 && Character.isLowerCase(currChar)) {
                char newChar = shiftedAlphabetLower.charAt(currentIndex);
                encrypted.setCharAt(index, newChar);
            }
            else if (currentIndex != -1) {
                char newChar = shiftedAlphabetUpper.charAt(currentIndex);
                encrypted.setCharAt(index, newChar);
            }
        }
        return encrypted.toString();
    }
    public String decrypt(String input) {
        OOCaesarCipher oocc = new OOCaesarCipher(26-mainKey);
        return oocc.encrypt(input);
    }
    }

Answer 1

对于您的解密方法，我相信您想返回原始输入字符串。要遵循代码的样式，您实际上可以使用26-key从解密方法中调用crypto方法，如下所示：

public String decrypt(String input) {
    mainKey1 = 26-mainKey1;
    mainKey2 = 26-mainKey2;
    String decrypted = CaeserCipherTwoKeys.encrypt(input);
    // To maintain code consistency
    mainKey1 = 26-mainKey1;
    mainKey2 = 26-mainKey2;

如何将一键密码更改为双键密码

1 个答案: