如何创建C＃Caesar Cipher？ [英] How do I create a C# Caesar Cipher?
问题描述
我正在尝试在C＃中创建一个密码，我需要从文本文档中获取加密文本，并在控制台中显示解密并将正确的解码导出到文本文档。
这是我到目前为止：
I'm trying to create a cipher in C#, I need to take in the encrypted text from a text document and have the decryptions show up in the console and have the correct one export to a text document.
This is what I have so far:
using System;
using System.IO;
public class cipher
{
public static void Main(string[] args)
{
string output = "";
int shift;
bool userright = false;
string cipher = File.ReadAllText("decryptme.txt");
char[] decr = cipher.ToCharArray();
do {
Console.WriteLine("How many times would you like to shift? (Between 0 and 26)");
shift = Convert.ToInt32(Console.ReadLine());
if (shift > 26) {
Console.WriteLine("Over the limit");
userright = false;
}
if (shift < 0) {
Console.WriteLine("Under the limit");
userright = false;
}
if (shift <= 26 && shift >= 0)
{
userright = true;
}
}
while (userright == false);
for (int i = 0; i < decr.Length; i++)
{
{
char character = decr[i];
character = (char)(character + shift);
if (character == '\'' || character == ' ')
continue;
if (character > 'Z')
character = (char)(character - 26);
else if (character < 'A')
character = (char)(character + 26);
output = output + character;
}
Console.WriteLine("\nShift {0} \n {1}", i + 1, output);
}
StreamWriter file = new StreamWriter("decryptedtext.txt");
file.WriteLine(output);
file.Close();
}
}
我现在卡住了，我把它放进了加密文本，但它不解密它。它只是在控制台中打印加密文本。任何帮助将不胜感激。
谢谢。
I'm stuck right now, I have it feed in the encrypted text but it doesn't decipher it. It just prints in the console the encrypted text. Any help would be appreciated.
Thanks.
推荐答案
试试这个 链接 。
首先提供已知文本：假设一个和文本HELLO
使用仅包含IFMMP的NotePad创建一个文本文件并保存。
在线上设置一个断点：
Start by feeding it "known" text: assume a shift of one and the text "HELLO"
Create a text file using NotePad that contains just "IFMMP" and save it.
Put a breakpoint on the line:
char character = decr[i];
并运行你的应用程序，将它提供给您刚创建的文本文件。
然后一次一行地执行您的程序，并查看到底发生了什么。
第一行应该获取加密的字符，下一个应该解密它 - 所以你显示能够在调试器中看到解密的字符。
应该立即明白问题是什么！ ：笑：
提示：你不需要走远就能发现问题......
And run your app, feeding it the text file you just created.
Then step through your program one line at a time, and look at exactly what is going on.
The first line should fetch the encrypted character, the next should decrypt it - so you shown be able to see the decrypted character in the debugger.
It should be immediately obvious what the problem is! :laugh:
Hint: you won't need to go far to spot the problem...
这是一个有点简单。使用mod处理界外数字：
This is a bit simpler. Uses mod to deal with numbers outside bounds:
private abstract class CharClass
{
//default shift
private static int _shift = 13;
//chars that can be shifted
private const string Alphabet = "abcdefghijklmnopqrstuvwxyz";
//update the shift number
public static int Shift
{
private get { return _shift; }
set { _shift = value; }
}
//perform the shift per char
public static char ShiftChar(char c)
{
var index = Alphabet.IndexOf(c);
if (index == -1)
return c;
index = ((index + Shift) + Alphabet.Length) % Alphabet.Length;
return Alphabet[index];
}
//perform the shift on a string
public static string ShiftString(string s)
{
return new string(s.Select(ShiftChar).ToArray());
}
}
用法:(好吧，我的测试方法）
usage: (well, my test method)
[TestMethod]
public void Test1()
{
CharClass.Shift = 5;
const string unEncrypted = "the quick brown fox jumps over the lazy dog";
var encrypted = CharClass.ShiftString(unEncrypted);
CharClass.Shift = -5;
var unEncryptedAgain = CharClass.ShiftString(encrypted);
Assert.IsFalse(unEncrypted.Equals(encrypted));
Assert.IsFalse(encrypted.Equals(unEncryptedAgain));
Assert.IsTrue(unEncrypted.Equals(unEncryptedAgain));
}
注意：
只有<$ c $中的字符c>字母将被移位。在这种情况下，大写字符不会，也不会是空格或特殊字符。
我可以更新此处理大写，但我我相信你可以管理它^ _ ^
希望有所帮助
Andy
NB:
ONLY the chars in Alphabet will be shifted. uppercase chars will not in this case, neither will whitespace or special chars.
I could update this to handle upper case too, but I'm sure you can manage it ^_^
Hope that helps
Andy
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