Rail Fence Cipher Implementation

This project implements the Rail Fence Cipher encryption and decryption in Rust. It demonstrates the correctness of the implementation through unit tests and provides a command-line interface for encrypting and decrypting text.

Features

• Encryption: Convert plaintext to ciphertext using the zigzag Rail Fence pattern.
• Decryption: Reconstruct plaintext from ciphertext using the Rail Fence pattern.
• Command-line Interface: Specify options like depth of the fence, input text, and whether to encrypt or decrypt.
• Unit Tests: Validate the correctness of the implementation with cargo test.

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Prerequisites

To build and run this project, make sure you have the following installed:

• Rust and Cargo

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How to Compile the Project

To compile the project, navigate to the project directory and run:

cargo build

This will create the compiled binary in the target/debug directory.

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How to Run the Program

Installation

git clone https://github.com/martian58/rail_fence.git
cd rail_fence
cargo run -- --help

You can use the cargo run command to execute the program. The program requires several arguments:

Basic Command Syntax

cargo run -- [OPTIONS]

Or

./target/debug/rail_fence [OPTIONS]

Get help

cargo run -- --help

Or

./target/debug/rail_fence --help

Example Commands

1. Encrypt a Message:

   cargo run -- -d 3 -i "HELLO"

   Output:

   Encrypted Text: HOELL
   

2. Decrypt a Message:

   cargo run -- -d 3 -i "HOELL" --decrypt

   Output:

   Decrypted Text: HELLO
   

Command-Line Options

Option	Description
-d, --depth	Depth of the Rail Fence cipher (number of rails). Required.
-i, --input	The text to encrypt or decrypt. Required.
-x, --decrypt	Decrypt the input text instead of encrypting it. Optional (default is encryption).

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How to Run Unit Tests

To validate the correctness of the implementation, run the unit tests using:

cargo test

Test Output

running 4 tests
test tests::test_encrypt ... ok
test tests::test_decrypt ... ok
test tests::test_encrypt_with_depth_4 ... ok
test tests::test_decrypt_with_depth_4 ... ok

test result: ok. 4 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out

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How to Clean the Project

To remove build artifacts and clean the project directory, run:

cargo clean

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Project Structure

• src/main.rs: Contains the implementation of the Rail Fence Cipher and the command-line interface.
• Cargo.toml: Manages dependencies and project metadata.
• README.md: Documentation for the project (this file).

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Example Usage

1. Encrypt a Longer Message:

   cargo run -- -d 4 -i "RAILFENCEISTHEBEST"

   Output:

   Encrypted Text: RNHAECTETIFESBSLIE
   

2. Decrypt the Same Message:

   cargo run -- -d 4 -i "RNHAECTETIFESBSLIE" --decrypt

   Output:

   Decrypted Text: RAILFENCEISTHEBEST
   

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Additional Notes

• Ensure the depth of the Rail Fence cipher (--depth) is at least 2.
• The input text can contain uppercase or lowercase characters, but the program will treat all characters as uppercase.
• Non-alphabetic characters are ignored during encryption/decryption.