Simple-Ciphers (RailFence, RotatingGrill, Vigenere)

RailFence cipher:

alphabet - English (ABCDEFGHIJKLMNOPQRSTUVWXYZ).
key - positive numbers (all other characters are ignored).

Available functions:

string Encrypt(string plaintext, string key)

Description:

Encrypts plaintext with a cipher "Rail-Fence" with the specified key.

Formal parameters:

plaintext - the text to be encrypted.
key - fence height.

Return value:

The ciphertext.

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string Decrypt(string ciphertext, string key)

Description:

Decrypts ciphertext with a cipher "Rail-Fence" with the specified key.

Formal parameters:

ciphertext - the text to decrypt.
key - fence height.

Return value:

Decrypted text.

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Principle of operation:

Encrypt:

1. Build a key-tall "rail fence".
2. Read characters from left to right from top to bottom.

Example:

key = 3
plaintext = "HELLOWORLD"

H          O           L
    E     L   W    R     D
       L           O

ciphertext = HOLELWRDLO"

Decrypt:

In order to decrypt the received text, it is necessary perform the reverse actions performed during encryption and use the same key.

RotatingGrill cipher:

alphabet - English (ABCDEFGHIJKLMNOPQRSTUVWXYZ).
key - array of holes in the grill.

Constructors:

public RotatingGrill()
{
    key[0] = new int[2] { 0, 0 };
    key[1] = new int[2] { 3, 1 };
    key[2] = new int[2] { 2, 2 };
    key[3] = new int[2] { 1, 3 };
}

Initializes the key with a default value.

Grill initialized with the default key (zeros - holes):

0   X   X   X
X   X   X   0
X   X   0   X
X   0   X   X

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public RotatingGrill(int[][] key, int grillSize)
{
    this.key = key;
    this.grillSize = grillSize;
}

Allows you to create your own grill with your own key.

Available functions:

string Encrypt(string plaintext, string key = null)

Description:

Encrypts text using the "rotating grill" algorithm.

Formal parameters:

plaintext - the text to be encrypted.
key - specified when creating the object.

Return value:

The ciphertext.

---

string Decrypt(string ciphertext, string key = null)

Description:

Decrypts the text using the "rotating grill" algorithm.

Formal parameters:

ciphertext - the text to decrypt. key - specified when creating the object.

Return value:

Decrypted text.

Principle of operation:

Encrypt:

1. Write the letters of the plaintext in free holes..
2. Rotate the grill 90 degrees.
3. Perform steps 1, 2 until you encrypt all the text.

Decrypt:

Perform reverse encryption actions.

Vigenere cipher:

alphabet - Russian (АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ).
key - characters of the Russian alphabet (all other characters are ignored).
The implementation of this cipher is made with a progressive key.

Constructors:

public Vigenere()
{
    alphabet = "АБВГДЕЁЖЗИЙКЛМНОПРСТУФХЦЧШЩЪЫЬЭЮЯ";
}

Initializes the alphabet to the default value.

public Vigenere(string alphabet)
{
    this.alphabet = alphabet;
}

Allows you to set your own alphabet.

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Available functions:

string Encrypt(string plaintext, string key)

Description:

Encrypts text using the "Vigenere" algorithm.

Formal parameters:

plaintext - the text to be encrypted.
key - the key for the lookup table.

Return value:

The ciphertext.

---

string Decrypt(string ciphertext, string key)

Description:

Decrypts text using the "Vigenere" algorithm.

Formal parameters:

ciphertext - the text to decrypt.
key - the key for the lookup table.

Return value:

Decrypted text.

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Principle of operation:

Encrypt:

1. Select a lookup table according to the current key characters.
2. Substitute a character with the character from the lookup table for the current plaintext character.

Decrypt:

Perform reverse encryption actions.