HashGuard

A lightweight file integrity checker written in C++20 for Windows.

HashGuard uses SHA-256 hashing to detect changes in files and directories. It supports recursive directory scanning, JSON baselines, and file integrity verification through a simple command-line interface.

Features

• SHA-256 hashing using Windows BCrypt
• Recursive directory scanning
• JSON baseline creation
• Detection of modified, added, and deleted files
• File integrity verification
• Command-line interface
• Execution time measurement

Requirements

• Windows 10 or 11
• Visual Studio 2026 with C++ desktop development tools
• C++20

Building

1. Clone or download the repository.
2. Open HashGuard.slnx in Visual Studio 2026.
3. Select Release and x64.
4. Build the solution.
5. Find HashGuard.exe in the build output directory.

Usage

Open CMD in the directory containing HashGuard.exe.

Hash a file

Calculate the SHA-256 hash of a single file.

HashGuard.exe hash "C:\files\test.txt"

Scan a directory

Recursively scan a directory and display file hashes and sizes.

HashGuard.exe scan "C:\files"

Create a baseline

Create a JSON baseline containing file paths, sizes, and SHA-256 hashes.

HashGuard.exe init "C:\files"

The baseline is saved as data.json in the parent directory of the scanned folder.

Verify file integrity

Compare the current directory contents against the saved baseline.

HashGuard.exe verify "C:\files"

Possible results:

• unchanged — File content has not changed.
• modified — File content has changed.
• added — A new file was detected.
• deleted — A previously recorded file is missing.

Help

Display available commands.

HashGuard.exe help

Example Output

modified -> test.txt
added -> new.txt

verification completed
unchanged -> 0
modified -> 1
added -> 1
deleted -> 0

time -> 2.41 ms

Performance

Initial SHA-256 performance measurements using the Release x64 build:

File size	Execution time
10 MiB	10.83 ms
100 MiB	102.93 ms

These are single-run measurements on one machine, including file I/O and command overhead. Results may vary depending on hardware and filesystem caching.

Dependencies

• nlohmann/json — JSON parsing and serialization
• Windows BCrypt API — SHA-256 hashing

Notes

• A baseline must be created before running verification.
• The baseline file is stored outside the scanned directory.
• Existing baselines are not overwritten by the init command.
• Baselines are not cryptographically authenticated and should be protected from unauthorized changes.
• File paths containing non-ASCII characters may not work correctly in the current CLI version.
• The application currently returns exit code 0 even when an error is reported.

License

This project is licensed under the MIT License.

Preview