Index file for Oclif CLI tutorial

index.ts

import {Command, flags} from '@oclif/command'
import * as inquirer from 'inquirer';
import * as fs from 'fs';
import cli from 'cli-ux';
import { createCipheriv, randomBytes, scryptSync } from 'crypto';

class Crypto extends Command {
  static description = 'describe the command here'

  static flags = {
    // add --version flag to show CLI version
    version: flags.version({char: 'v'}),
    help: flags.help({char: 'h'}),
    // flag with a value (-n, --name=VALUE)
    name: flags.string({char: 'n', description: 'name to print'}),
    // flag with no value (-f, --force)
    force: flags.boolean({char: 'f'}),
  
    // Our new input flags
    input: flags.string({ default: '' }),
    algorithm: flags.string({ 
      options: ['aes-192-cbc', 'aes-256-cbc', 'des-ede3'] 
    }),
    password: flags.string({}),
  };
  
  static args = [
    // Our new input arguments
    {name: 'input'},
    {name: 'algorithm'},
    {name: 'password'}
  ];

  async run() {
    // Pulls args and flags variables from Crypto class
    const {args, flags} = this.parse(Crypto)
    // Destructure flags object to get input and algorithm
    let { input, algorithm, password } = flags;
  
    // If input variable is undefined...
    if (!input) {
      // cli-ux and 'cli' object provide utilities to interact
      //  with the Oclif API.
      input = await cli.prompt('String to be encrypted');
    }
    // If algorithm variable is undefined...
    if (!algorithm) {
      // inquirer is an add-on for Oclif that allows us to
      //  take different kinds of input - in this case a list
      const select = await inquirer.prompt([{
        name: 'algorithm',
        message: 'Select encryption algorithm',
        type: 'list',
        choices: [
          { name: 'aes-192-cbc' },
          { name: 'aes-256-cbc' },
          { name: 'des-ede3' },
        ],
      }]);
      // Assign user input to algorithm variable
      algorithm = select.algorithm;
    }
    // If password is undefined...
    if (!password) {
      password = await cli.prompt('Password for encryption key');
    }

    // Encryption key length is dependent on algorithm
    let keyLength: number;
    switch(algorithm) {
      case "aes-192-cbc":
        keyLength = 24;
        break;
      case "aes-256-cbc":
        keyLength = 32;
        break;
      case "des-ede3-cbc":
        keyLength = 7;
        break;
      default:
        keyLength = 24;
        break;
    }
    // Generate encryption key from password and keyLength
    const key = scryptSync(password ? password : 'password', 'salt', keyLength);
    // Define IV (Initialization vector)
    const iv = Buffer.alloc(16, 0);
    // Create Cipher object 
    const cipher = createCipheriv(
      algorithm ? algorithm : 'aes-192-cbc',
      key,
      // des-ede3 algorithm does not use iv
      algorithm === 'des-ede3' ? '' : iv
    );

    this.log(`\n// Input string: ${input}`);
    this.log(`// Algorithm: ${algorithm}`);
    this.log(`// Cipher password: ${password}\n`);

    let encrypted: string = cipher.update(input, 'utf8', 'hex');
    encrypted += cipher.final('hex');
    this.log(`OUTPUT: ${encrypted}`);
  }
}

export = Crypto