维吉尼亚加密

Question

我一直在用凯撒密码和维吉尼亚密码进行一个项目。我已经想出了凯撒密码，但我正在为 Vigenère 密码苦苦挣扎。

我的加密代码分为两部分：encrypt()和encrypt1()。 encrypt() 方法提取每个字符并将其传递给 encrypt1()，基本上所有的加密都在这里进行。我在这里做了代码，但它没有给我任何好的结果。

例如，如果 new VigenereCipher("SLIME").encrypt("GREEN") 其中 "SLIME" 是密钥密码，"GREEN" 是应加密为 YcMQR 的字符串。但是我的代码给出了 ?&|{。

考虑字母表对象涵盖所有内容 = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz 1234567890!@#$%^&*()_+-=[]{}\|;:'\",./?<>"

有人可以帮我吗？

public class VigenereCipher extends SymmetricCipher {

    protected String password;
    protected int passwordPos;

    public VigenereCipher(String password, Alphabet alphabet)
    {
        super(alphabet);
        this.password = password;
    }
    public VigenereCipher(String password)
    {
        super(Alphabet.DEFAULT);
        this.password = password    ;
    }

    public String getPassword()
    {
        return this.password;
    }



    public String encrypt(String s)
    {
        passwordPos = 0;
        String encrypted = "";
        for(int i = 0; i < s.length(); i++)
        {
            char c = s.charAt(i);
            encrypted += encrypt1(c);

        }


        return encrypted;
    }

    protected char encrypt1(char c)
    {
        //Alphabet temp = new Alphabet(s);
        int index = 0;
        char result = 0;

        index = alphabet.indexOf(c); //Found index of a character 

        if(index != -1)
        {
            int keyIndex = alphabet.get(passwordPos++ % password.length());
            result = alphabet.get((keyIndex + index) % alphabet.length());
        }
        else 
            throw new NotInAlphabetException(c, alphabet);
        return result;
    }

    public String decrypt(String c)
    {
        return c;
    }

    protected char decrypt1(char c)
    {
        return c;
    }

    public String toString()
    {
        return "Vigenere Cipher (password =\'"+this.password+"\')"; 
    }



}


public abstract class SymmetricCipher extends Cipher {

    protected Alphabet alphabet;

    public SymmetricCipher (Alphabet alphabet)
    {
        this.alphabet = alphabet;
    }

    public int wrapInt(int i)
    {
        int index = 0;
        if (i >= alphabet.length())
            index = Math.abs(i) % alphabet.length();
        else if (i < 0)
        {
            int temp = Math.abs(i) % alphabet.length();
            index = alphabet.length() - temp;
        }
        else 
            index = i;

        return index;
    }

    public int rotate(int index, int shift)
    {
        int result = 0;

        if (shift > 0)
        {
            result = (index + shift) % alphabet.length();
        }

        else if (shift < 0)
        {
            if(index < Math.abs(shift))
            {
                int temp = Math.abs(index + shift);
                result = alphabet.length() - temp;

            }
            else 
                result = index + shift ;
        }   


        return result;
    }

    public Alphabet getAlphabet()
    {
        return this.alphabet;
    }

    public String encrypt(String s) 
    {
        String string = "";
        char c = 0;
        char encrypted = 0;
        for (int i = 0; i < s.length(); i++)
        {
            c = s.charAt(i);
            encrypted = encrypt1(c);
            string += encrypted;
        }
        return string;


    }

    public String decrypt(String s) throws NotInAlphabetException
    {
        String string = "";
        char c = 0;
        char encrypted = 0;
        for (int i = 0; i < s.length(); i++)
        {
            c = s.charAt(i);
            encrypted = encrypt1(c);
            string += encrypted;
        }
        return string;


    }

    protected abstract char encrypt1(char c);

    protected abstract char decrypt1(char c);


}



public class Alphabet {


    private String symbols;
    public static final Alphabet DEFAULT = new Alphabet("ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz 1234567890!@#$%^&*()_+-=[]{}\|;:'\",./?<>");

    public Alphabet(String symbols)
    {
        this.symbols = symbols;
    }

    public int indexOf(char c) 
    {
        Alphabet temp = new Alphabet(symbols);
        for(int i = 0; i < symbols.length(); i++)
        {
            if(c == symbols.charAt(i))
                return symbols.indexOf(c) ;
        }

        throw new NotInAlphabetException (c, temp); 
    }

    public char get(int i) 
    {
        Alphabet temp = new Alphabet(symbols);
        char c = 0;
        if (i > this.symbols.length())
            throw new NotInAlphabetException (c, temp);
        else 
            return symbols.charAt(i);
    }

    public int length()
    {
        return symbols.length();
    }

    public String getSymbols()
    {
        return symbols;
    }

    public String toString()
    {
        return "Alphabet("+this.symbols+")";
    }

    public boolean equals(Object other)
    {
        if(other instanceof Alphabet)
        {
            Alphabet temp = (Alphabet) other;
            return this.symbols.equals(temp.symbols);

        }
        else 
            return false;
    }
}

Answer 1

问题出在 encrypt1 函数的这一行：

int keyIndex = alphabet.get(passwordPos++ % password.length());

此处您试图在密码中查找密钥，但实际上是从 字母表 中获取的。你想要的是从密码中找到相关字符（到达末尾时循环），然后找出该字符在你的字母表中的索引，这样你就可以获取平面文本并将其移动（ index) 字母表中的许多字符。

为此，您可以使用此代码：

char pwChar = password.charAt(passwordPos++ % password.length());
int keyIndex = alphabet.indexOf(pwChar);

当我更改此行和运行你的代码时 SLIME 作为密钥，GREEN 作为明文，我得到结果 YcMQR，这就是你说你期待。

维吉尼亚加密

Vigenère encryption

java

encryption

vigenere