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Asked: 2024-09-27T06:51:31+05:30 In: ,

How can I implement the Vic cipher for encoding and decoding messages with Python or JavaScript?

So, I recently stumbled upon an interesting cipher called the Vic cipher, and I’ve been trying to get my head around decoding and encoding messages using it. It’s a bit of a challenge, and I thought it would be cool to see how others tackle the problem too!

Here’s the deal: the Vic cipher uses a keyword to generate a matrix that helps encode and decode messages. The matrix is built by taking the keyword and filling it in with letters of the alphabet (skipping duplicates), followed by the remaining letters of the alphabet that weren’t included in the keyword. It’s like a blend of a classic substitution cipher and a transposition cipher, but with that unique twist of the keyword-driven matrix.

Let’s say we have the keyword “CIPHER” for our little exercise. So, we’d start off by making a matrix that begins with C, I, P, H, E, and R. We would then fill in the rest of the matrix with the letters A through Z, excluding those already in “CIPHER.” The challenge ramps up a bit when you consider that we’ll need to handle spaces, punctuation, and potentially even numbers in our messages too!

I’m really curious to see how different people would approach writing a programmer’s function to decode a message encrypted with the Vic cipher. What would your function look like? Could you walk me through how you’d encode a message using the keyword? Also, how would you handle unexpected characters?

One thing I find especially tricky is maintaining the original spacing from the plain text in the encoded message. And what do you think about performance? Since we might be decoding straight into a string from an input, I’m wondering how that impacts speed, especially with longer keywords or texts.

I’d love to see some sample code, maybe in Python or JavaScript, and hear about any challenges you faced while figuring it out. Also, if you have some nifty tricks or tips for optimizing the decoding process, please share! Would be awesome to have a discussion about this!

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    2 Answers

    1. Vic Cipher Encoding and Decoding

      So, here’s a quick rundown of how to use the Vic cipher with a given keyword, like “CIPHER”. We’ll need to create a matrix based on that keyword and then use it to encode and decode messages. Below, I’ll show you how to do that in Python!

      def create_matrix(keyword):
    # Remove duplicates and create the base of the matrix
    keyword = ''.join(dict.fromkeys(keyword.upper()))
    alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    # Create the matrix with the keyword first
    matrix = list(keyword)
    for letter in alphabet:
        if letter not in matrix:
            matrix.append(letter)
    return [matrix[i:i + 6] for i in range(0, 36, 6)]  # Create 6x6 matrix

def encode(plaintext, keyword):
    matrix = create_matrix(keyword)
    encoded_message = ""
    
    for char in plaintext:
        if char.upper() in ''.join(matrix):
            index = ''.join(matrix).index(char.upper())
            row = index // 6
            col = index % 6
            encoded_message += f"{row}{col} "  # Using row and column as encoded form
        else:
            encoded_message += char  # Keep spaces and punctuation as is
    
    return encoded_message.strip()

def decode(encoded_message, keyword):
    matrix = create_matrix(keyword)
    decoded_message = ''
    pairs = encoded_message.split()
    
    for pair in pairs:
        if pair.isdigit() and len(pair) == 2:
            row, col = int(pair[0]), int(pair[1])
            decoded_message += matrix[row][col]
        else:
            decoded_message += pair  # Keep non-numeric characters as is
            
    return decoded_message

# Example usage
keyword = "CIPHER"
plaintext = "HELLO WORLD"
encoded = encode(plaintext, keyword)
decoded = decode(encoded, keyword)

print(f"Encoded: {encoded}")
print(f"Decoded: {decoded}")

      Handling unexpected characters like spaces and punctuation means we just keep them in their original form when encoding and decoding. I used if char.upper() in ''.join(matrix) to check if the character exists in the matrix. If it does, we convert it; if not, we just append it as is.

      As for performance, using a matrix of size 6×6 keeps things quick since you’re not dealing with massive data sets. The key is to efficiently find characters and handle them. If you ever run into memory or speed issues, consider tuning the algorithm or using optimized data structures.

      Feel free to play around with this code and make it your own!

    2. The Vigenère cipher is a fascinating encryption technique that certainly presents some unique challenges. To encode a message using a keyword, we first create a matrix based on that keyword. For example, using the keyword “CIPHER”, we would construct a 5×5 matrix as follows. Start with the keyword letters (C, I, P, H, E, R) and then fill in the remaining spots with the leftover letters of the alphabet in order, skipping duplicates: C I P H E R A B D F G J K L M N O Q S T U V W X Y Z. When encoding, you look up each letter in your plaintext against this matrix while considering both the keyword and the position of each letter in the message.

      In Python, we can implement the encoding process using a function that captures the generation of the matrix and the actual encoding of the text. Below is a simple representation of how you can accomplish this. This implementation will also handle spaces and punctuation by leaving them unchanged and will maintain the original message’s structure. When it comes to performance, ensure that the matrix generation occurs once, rather than on every character lookup, to optimize speed.


      def create_matrix(keyword):
      matrix = []
      seen = set()
      for char in keyword:
      if char not in seen:
      seen.add(char)
      matrix.append(char)
      for letter in 'ABCDEFGHIJKLMNOPQRSTUVWXYZ':
      if letter not in seen:
      matrix.append(letter)
      return matrix

      def encode_vigenere(message, keyword):
      matrix = create_matrix(keyword)
      encoded = ""
      keyword_repeated = (keyword * (len(message) // len(keyword))) + keyword[:len(message) % len(keyword)]
      for m_char, k_char in zip(message, keyword_repeated):
      if m_char.isalpha():
      row = ord(k_char.upper()) - ord('A')
      col = ord(m_char.upper()) - ord('A')
      encoded += matrix[(row * 26 + col)]
      else:
      encoded += m_char # Preserve spaces and punctuation
      return encoded

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