cipherworld-antony-mse-2103-a README

cipherworld-antony-mse-2103-a is a JavaScript library used to encode and decode .txt files.

How to install the program

With the command line, navigate to the directory containing the text files that you want to encrypt or decrypt. Enter:

$ npm install cipherworld-antony-mse-2103-a

Directory information

• test_files - Directory containing 4 test files to be encrypted or decrypted
• characterSets - Directory containing the character sets that will be used for each cipher
  • character_set.txt is used for the letterNumber cipher
  • character_set2.txt is used for the letterLetter cipher
  • More character sets can be added in future

How to run code

Navigate to the project directory through the command line.

The command will take 3 or 4 arguments outlined below.

Input :

$ npx cipherWorld [character set] [cipher] [method] [file] <key>

• npx - node package execute

• character set - the file containing the necessary character set for your chosen cipher. Current possible inputs are character_set.txt (for letter number ciphers) and character_set2.txt (for letter letter ciphers)

• cipher - Use letterLetter or ll if you want to use the LetterLetter cipher. Use letterNumber or ln if you want to use the LetterNumber cipher.

• method - Use encrypt or enc to encrypt a file. Use decrypt or dec to decrypt a file.

• file - the filepath for the .txt file that needs encypting/decrypting

• key - Optional. Used for letterNumber ciphers

• This will create a new file for with the encrypted/decrypted output and store it in the same directory as the original file.

• The ciphers currently work off two character sets, the letterNumberCipher uses character_set.txt while the letterLetterCipher (cipher.js) uses character_set2.txt

• Using a letterNumber cipher input ln requires a key. This offsets the value returned value of the cipher by the value of the key

  • E.g. with no key - "d" = 6
  • With key = 3 - "d" = 9

• The key can be any integer >= 0, if key > 99 the cipher rolls over to 0 and keeps offsetting

• See expected outputs for further details

Example Files

This module comes with 4 example files that are located in:

[project_directory]/node_modules/cipherworld-antony-mse-2103-a/text_files

For ease of use, copy/move these files to your working directory to test package.

Expected outputs

To easily test the examples below, move/copy the files from node_modules/cipherworld-antony-mse-2103-a/text_files into your current working directory

Example 1:

Encrypt testLNEnc.txt with key 31045 - LetterNumber Cipher input code: (Using the test files without moving from their original directory: )

$ npx cipherWorld character_set.txt ln enc node_modules/cipherworld-antony-mse-2103-a/test_files/testLNEnc.txt 31045

or if moving the testLNEnc.txt file to the current working director

$ npx cipherWorld character_set.txt ln enc testLNEnc.txt 31045

Expected output: A new text file called testLNEnc.txt.enc containing:

97747470597481647759796764776413

Example 2:

Decrypt testLNDec.txt.enc with key 4771 - LetterNumber Cipher input code:

$ npx cipherWorld letterNumber decrypt testLNDec.txt.enc 4771

Expected output: A new text file called testLNDec.txt containing:

Hi, Ed! I think someone's on to this cipher!

Example 3:

Encrypt testLLEnc.txt - LetterLetter Cipher input code:

$ npx cipherWorld ll encrypt testLLEnc.txt

Expected output: A new text file called testLLEnc.txt.enc containing:

B!!ym!9DAm2§DAD

Example 4:

Decrypt testLLDec.txt.enc - LetterLetter Cipher input code:

$ npx cipherWorld ll dec testLLDec.txt.enc

Expected output: A new text file called testLLDec.txt containing:

Quick! We need a distraction! Once you read this message, find the community channel named "random" on Discord, and share a random fact regarding any insect - but it has to be about insects! Fingers crossed this will distract and slow down the people cracking these ciphers!

Approach to getting to this point

• As the letterLetter Cipher and letterNumber cipher had previously been made, I started by recreating those classes.

  • Split them into their own files and reworked them to make them more streamline, easier to read and efficient
  • invertCipher.js and readCipher.js were two methods that I extracted into their own files. They are used in both types of ciphers
    • In future work, maybe create a Cipher parent class that contains invertCipher and readCipher, and have LetterLetter and LetterNumber and child classes.

• Majority of work on solveCipher.js. Needed to create a method that would choose the appropriate cipher and appropriate method depending on the input.

  • Started as one long method that i wrote until it was able to run as expected
  • Then i refacactored the file into multiple methods that were called by the solveCipher method

• Throughout the project, using console.log to check each method and file and debug as I worked through the task

  • e.g. checking that letterNumber.js ran as expected before moving on to letterLetter.js and so on
  • This way, when working on solveCipher.js I could trust the output of each method would be what was intended

• After solveCipher.js was workign and creating new text files. Moved onto main.js

  • Needed this to read the console input and execute solveCipher()
  • Researched and experimented with process.argv to save the input as an array to be used as solveCipher() arguments

• Main problems encountered with file sources, what is the best way to input a file source to the console / input it in your code?

  • e.g.

  return new LetterNumber('src/character_set.txt')

  -This file source will work for this directory, but will it cause problems if the directory is moved/ when the repository is cloned to a different device.

• Next challenge was to turn the program into a npm package

  • Started by researching how to create a package from the npm documentation
  • Found a couple of informative youtube videos (https://www.youtube.com/watch?v=N55jHr9qzpg&ab_channel=AndrewMead)

• Created the package.json file and used npm link to test the code by using require() in another directory

  • Had to rework some of the file paths for the .readFile() of character_set.txt and character_set2.txt within solveCipher.js so that the code would work when installed in another directory.
  • This ended up only being a temporary solution, as the file path now ran through node_modules (more explained later)

• Was able to get the code working in a different directory but was not calling cipherWorld directly through the command line

• After more research, configured the bin key in package.json and created a bin directory.

  • Set up the cipherWorld.js file to run in the node environment, store command line input and execute solveCipher

• Final block was with the file paths found in solveCipher.js when creating a new LetterLetterCipher or LetterNumberCipher class. -The file path was a relative string to character_set.txt but it would not work when the node package was installed in a different directory

  • Found that i needed to change the input to ${__dirname}/character_set.txt so that it would look for character set files from the same directory as solveCipher.js

• Now able to execute cipherWorld from the command line to encrypt and decrypt text files

• Extensive research into yargs to configure the cipherWorld command with positionals, options, choices, and examples

  • Still more work can be done to improve this
  • Lots of new stuff with yargs trying to get my head around how things work and what each function does
  • Tried to keep it basic for now