crypto-keygen-suite/keyGen/encryptandecrypt/ciphers/vigenereciphergenerator.js

Key generation utilities for cryptographic operations. YES I RENAMED IT OMG BASES AND PROTOCOLS!!! See its folder for all <3

// what am i doing with my life

import yargs from 'yargs/yargs';
import { hideBin } from 'yargs/helpers';

function vigenereCipher(message, keyword, encrypt = true) {
  const result = [];
  const keywordRepeater = keyword.repeat(Math.ceil(message.length / keyword.length)).toUpperCase();
  
  for (let i = 0, j = 0; i < message.length; i++) {
      const char = message[i];
      if (char.match(/[a-z]/i)) { 
          const code = char.charCodeAt(0);
          const base = code >= 65 && code <= 90 ? 65 : 97; 
          const shift = keywordRepeater[j].charCodeAt(0) - 65; 
          const newChar = String.fromCharCode(((code - base + (encrypt ? shift : -shift) + 26) % 26) + base);
          result.push(newChar);
          j++; 
      } else {
          result.push(char); 
      }
  }

  return result.join('');
}

const argv = yargs(hideBin(process.argv))
    .option('message', {
        alias: 'm',
        description: 'The message to encrypt or decrypt',
        type: 'string',
        demandOption: true
    })
    .option('keyword', {
        alias: 'k',
        description: 'The keyword used for encryption or decryption',
        type: 'string',
        demandOption: true
    })
    .option('encrypt', {
        alias: 'e',
        description: 'Set to true to encrypt, false to decrypt',
        type: 'boolean',
        default: true
    })
    .help()
    .argv;

const result = vigenereCipher(argv.message, argv.keyword, argv.encrypt);
console.log('Result:', result);