java中的简单凯撒密码

问题描述

嘿，我正在使用公式 [x-> (x+shift-1) mod 127 + 1] 在 Java 中制作一个简单的凯撒密码，我希望我的加密文本具有除控制字符之外的 ASCII 字符(即从32-127).如何避免在加密文本中应用 0-31 的控制字符.谢谢.

Hey I'm making a simple caesar cipher in Java using the formula [x-> (x+shift-1) mod 127 + 1] I want to have my encrypted text to have the ASCII characters except the control characters(i.e from 32-127). How can I avoid the control characters from 0-31 applying in the encrypted text. Thank you.

推荐答案

这样的事情怎么样:

public String applyCaesar(String text, int shift)
{
    char[] chars = text.toCharArray();
    for (int i=0; i < text.length(); i++)
    {
        char c = chars[i];
        if (c >= 32 && c <= 127)
        {
            // Change base to make life easier, and use an
            // int explicitly to avoid worrying... cast later
            int x = c - 32;
            x = (x + shift) % 96;
            if (x < 0) 
              x += 96; //java modulo can lead to negative values!
            chars[i] = (char) (x + 32);
        }
    }
    return new String(chars);
}

诚然，这将 127 视为非控制字符，但实际上并非如此……您可能希望对其进行调整以保持范围为 [32, 126].

Admittedly this treats 127 as a non-control character, which it isn't... you may wish to tweak it to keep the range as [32, 126].

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