Caesar Cipher command line tool

Caesar Cipher is an algorithm that shifts symbols of input data by user defined offset.

This command line tool provides capability to shift bytes in ranges [65, 90] and [97, 122] of provided input (file and standard input are both supported) and write it to user defined output (can be either standard output or a file).

Prerequisites for compiling code yourself

• .NET 5
• Both of the listed IDEs have been confirmed to work:
  • Microsoft Visual Studio 2019
  • JetBrains Rider

Unit testing results

Refer to: Unit Testing Result README.md

Usage

Command line interface only accepts either 1 or 3 commands - help or {shift} {input} {output} where:

• help provides usage instructions.
• {shift} is a number in range [1, 25] by which to offset bytes of provided input.
• {input} is either a file path or standard input marked by "-".
• {output} is either a file path or standard output marked by "-".

⚠️ If {output} file already exists - it will rewritten!

To decrypt previously encrypted data - calculate 26 - {shift} and use value in place of {shift}.

For example if data was encrypted with {shift} of 5 - it can be decrypted with 21 as 26 - 5 = 21.

Usage examples

• Using no files and {shift} of "5" with decryption shift being "21":

  echo Hello World! | CaesarCipher 5 - - which results in Mjqqt Btwqi!.

  Passing said output into the tool again with decryption {shift} like so:

  echo Hello World! | CaesarCipher 5 - - | CaesarCipher 21 - -

  Results in Hello World!.

• Using files and {shift} of "7" with decryption shift being "19":

  For example file data.txt in the same directory as the executable contains:

  The quick brown fox jumps over the lazy dog.

  Running it through the tool: CaesarCipher 7 data.txt encrypted.txt

  Will create a file encrypted.txt in the same directory as executable with obviously garbled content:

  Aol xbpjr iyvdu mve qbtwz vcly aol shgf kvn.

  Running encrypted file through the tool with decryption {shift} like so:

  CaesarCipher 19 encrypted.txt decrypted.txt

  Will result in file decrypted.txt with content:

  The quick brown fox jumps over the lazy dog.

• Using a mix of both files and standard input/output:

  CaesarCipher 7 data.txt - results in Aol xbpjr iyvdu mve qbtwz vcly aol shgf kvn.

  Piping said output through CaesarCipher 7 data.txt - | CaesarCipher 19 - - will result in:

  The quick brown fox jumps over the lazy dog.

  Using CaesarCipher 7 data.txt - | CaesarCipher 19 - copy.txt will result in file copy.txt with content:

  The quick brown fox jumps over the lazy dog.

Known behavior

• {output} files are overwritten.
• Launching tool with input method as standard input like so CaesarCipher 5 - - and then not providing said input will result in application waiting. Forever, if necessary.