Question

我想制作加密方法，接受大写和小写都在纯文本变量中（“Hello World”它只接受小写字母请帮助我，我想要amke 它的工作正常，只有小写字母作为输入请帮助我

            using System;

        class SubstitutionCipher
        {
           static void Main()
           {
              string key = "jfkgotmyvhspcandxlrwebquiz";
              string plainText = "the quick brown fox jumps over the lazy dog";
              string cipherText = Encrypt(plainText, key);
              string decryptedText = Decrypt(cipherText, key);
              Console.WriteLine("Plain     : {0}", plainText);
              Console.WriteLine("Encrypted : {0}", cipherText);
              Console.WriteLine("Decrypted : {0}", plainText);
              Console.ReadKey();
           }
    //encryption method 
           static string Encrypt(string plainText, string key)
           {
              char[] chars = new char[plainText.Length];
              for(int i = 0; i < plainText.Length; i++)
              {
                 if (plainText[i] == ' ')
                 {
                    chars[i] = ' ';
                 }   
                 else
                 {
                    int j = plainText[i] - 97;
                    chars[i] = key[j];
                 }
              }
              return new string(chars);
           }
//decryption method
           static string Decrypt(string cipherText, string key)
           {
              char[] chars = new char[cipherText.Length];
              for(int i = 0; i < cipherText.Length; i++)
              {
                 if (cipherText[i] == ' ')
                 {
                    chars[i] = ' ';
                 }   
                 else
                 {
                    int j = key.IndexOf(cipherText[i]) - 97;
                    chars[i] = (char)j;
                 }
              }
              return new string(chars);
           } 
        }

Answer 1

您正在减去'a'，这仅适用于小写字符。你应该检查它是大写还是小写，然后分别减去A或a。此外，您可以直接使用“a”或“A”来获得与int等效的字符。

我的意思是将此用于解密和加密的else语句：

    static string Encrypt(string plainText, string key)
    {
        char[] chars = new char[plainText.Length];
        for (int i = 0; i < plainText.Length; i++)
        {
            if (plainText[i] == ' ')
            {
                chars[i] = ' ';
            }
            else if (Char.IsUpper(plainText[i]))
            {
                int j = plainText[i] - 'A';
                chars[i] = key[j];
            }
            else
            {
                int j = plainText[i] - 'a';
                chars[i] = key[j];
            }
        }
        return new string(chars);

    static string Decrypt(string cipherText, string key)
    {
        char[] chars = new char[cipherText.Length];
        for (int i = 0; i < cipherText.Length; i++)
        {
            if (cipherText[i] == ' ')
            {
                chars[i] = ' ';
            }
            else if (Char.IsUpper(cipherText[i]))
            {
                int j = key.IndexOf(cipherText[i]) - 'A';
                chars[i] = (char)j;
            }
            else
            {
                int j = key.IndexOf(cipherText[i]) - 'a';
                chars[i] = (char)j;
            }
        }
        return new string(chars);
    }

或加密和解密的短版本：

            else 
            {
                int j = Char.IsUpper(plainText[i]) ? plainText[i] - 'A' : plainText[i] - 'a';
                chars[i] = key[j];
            }

            else
            {
                int j = Char.IsUpper(cipherText[i]) ? key.IndexOf(cipherText[i]) - 'A' :  key.IndexOf(cipherText[i]) - 'a';
                chars[i] = (char)j;
            }

修改

好的，我认为算法已经完成了，我刚刚修复了导致异常的部分。但是，你是：

a）没有考虑哪个字母是大写的 b）没有工作的Decryptor。（我认为它有效，但是你的主要方法有明文结果作为解密的消息）。

要修复您的解密器，您需要在加密器上添加一种存储大写字母的方法。你可以对它更加复杂，但是现在，我们只是将其加密为密文上的大写字母。

static string Encrypt(string plainText, string key) { char[] chars = new char[plainText.Length]; for (int i = 0; i < plainText.Length; i++) { if (plainText[i] == ' ') { chars[i] = ' '; } else { int j = Char.IsUpper(plainText[i]) ? plainText[i] - 'A' : plainText[i] - 'a'; chars[i] = Char.IsUpper(plainText[i]) ? Char.ToUpper(key[j]) : key[j]; } } return new string(chars);

解密你应该在键上找到它作为小写字符，但输出为大写字符。

static string Decrypt(string cipherText, string key) { char[] chars = new char[cipherText.Length]; for (int i = 0; i < cipherText.Length; i++) { if (cipherText[i] == ' ') { chars[i] = ' '; } else { int j = Char.IsUpper(cipherText[i]) ? key.IndexOf(Char.ToLower((char)cipherText[i])) + 'a' : key.IndexOf(cipherText[i]) + 'a'; chars[i] = Char.IsUpper(cipherText[i]) ? Char.ToUpper((char)j) : (char)j; } } return new string(chars); }

Answer 2

这是一个有趣的问题，尤其是在一般情况中陈述时。所以我们有

密钥中的字符，这些字符应该是ecnrypted（例如a，j）
不在密钥中的字符，应跳过这些字符（例如 space ）

为了提高效率，让我们设计一个Encryptor \ Decryptor作为Dictionary<Char, Char>，为了做到这一点，我们应该对密钥中的字符进行排序并对其进行对应; 例如为了

  key        = "jfkgo"
  sorted key = "fgjko"

对将是

  {j, f} // when encrypting "j" becomes "f", on decryption "f" turns into "j"
  {f, g}
  {k, j}
  {g, k}
  {o, o}

从加密时，我们有加密，当从右到左读 解密时：< / p>

private static Dictionary<Char, Char> Encryptor(String key) {
  Char[] data = key.ToArray();
  Char[] sorted = data.OrderBy(c => c).ToArray();

  return data
    .Zip(sorted, (plain, encrypted) => new {
         Plain = plain,
         Encrypted = encrypted
     })
    .ToDictionary(item => item.Plain, item => item.Encrypted);
}

// Note, that Decryptor is the same as Encryptor by for the last line
private static Dictionary<Char, Char> Decryptor(String key) {
  Char[] data = key.ToArray();
  Char[] sorted = data.OrderBy(c => c).ToArray();

  return data
    .Zip(sorted, (plain, encrypted) => new {
      Plain = plain,
      Encrypted = encrypted
    })
    .ToDictionary(item => item.Encrypted, item => item.Plain);
}

现在，实现加密和解密方法很容易

private static String Encrypt(String source, String key) {
  var dict = Encryptor(key);

  StringBuilder Sb = new StringBuilder(source.Length);

  Char sub;

  foreach (var ch in source)
    if (dict.TryGetValue(ch, out sub))
      Sb.Append(sub);
    else
      Sb.Append(ch);

  return Sb.ToString();
}

 // Note, that Decryptor is the same as Encryptor by for the first line
private static String Decrypt(String source, String key) {
  var dict = Decryptor(key);

  StringBuilder Sb = new StringBuilder(source.Length);

  Char sub;

  foreach (var ch in source)
    if (dict.TryGetValue(ch, out sub))
      Sb.Append(sub);
    else
      Sb.Append(ch);

  return Sb.ToString();
}

小测试

 // For test, let capital letters mmimic the small ones
 string key = "jfkgotmyvhspcandxlrwebquiz" + "jfkgotmyvhspcandxlrwebquiz".ToUpper();

 string plainText = "The Quick Brown Fox Jumps Over The Lazy Dog!";
 string cipherText = Encrypt(plainText, key);
 string decryptedText = Decrypt(cipherText, key);

 Console.WriteLine("Plain     : {0}", plainText);
 Console.WriteLine("Encrypted : {0}", cipherText);
 Console.WriteLine("Decrypted : {0}", plainText);

使用c＃替换密码区分大小写

2 个答案: