Slashsum 🔍

Multi-threaded file checksum calculator

⚡ Calculate multiple file checksums simultaneously with blazing-fast performance using Rust's concurrency capabilities.

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📑 Table of Contents

• 🚀 Quick Start
• ✨ Features
• 📸 Screenshot
• 📦 Installation
• 🛠️ Usage
• 📈 Performance Benchmarks
• ⚖️ Comparison with Alternatives
• 🧠 How It Works
• 🔧 Technical Details
• ❓ FAQ
• 🗑️ Uninstall
• 📚 Dependencies
• 🤝 Contributing
• 📋 Changelog
• 👤 Author
• 📜 License

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🚀 Quick Start

# Linux (Snap Store - recommended)
sudo snap install slashsum

# Linux (Debian/Ubuntu)
sudo apt install ./slashsum_v*_amd64.deb

# Windows (download installer from releases page)
# Run slashsum-setup-user-v*.exe

# Calculate checksums
slashsum myfile.iso

# Save results to file
slashsum myfile.iso --save

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✨ Features

• ⚡ Parallel computation of 5 hash algorithms simultaneously
• 📊 Supported algorithms:
  • CRC32 (IEEE 802.3)
  • MD5
  • SHA-1
  • SHA-256
  • SHA-512
• 📁 Large file support (>10GB tested)
• 💾 Save results to .checksum files
• ⏱️ Execution time metrics
• 🖥️ Cross-platform (Windows/Linux/macOS)
• 🎯 Zero configuration - works out of the box
• 🪶 Lightweight - single binary, no dependencies

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📸 Screenshot

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📦 Installation

Option 1: Linux (Snap Store) - Recommended ⭐

sudo snap install slashsum

🔄 Auto-updates enabled. View on Snap Store

Option 2: 🐧 Linux (Portable)

Download the portable package from the releases page:

tar -xzvf slashsum-linux-amd64-portable.tar.gz
cd slashsum-linux-amd64-portable
sudo ./install.sh

Option 3: 🐧 Linux (DEB - Debian/Ubuntu/Linux Mint)

Download the .deb file from the releases page:

sudo apt install ./slashsum_<version>_amd64.deb

Option 4: 🐧 Linux (Snap from GitHub Release)

sudo snap install --dangerous slashsum_<version>_amd64.snap

Option 5: 🪟 Windows (Installer) - Recommended ⭐

Download the installer from the releases page:

Installer	Description	Admin Required
slashsum-setup-user-<version>.exe	👤 Current user only	No
slashsum-setup-admin-<version>.exe	🔐 System-wide	Yes

Option 6: 🪟 Windows (Portable)

Download slashsum-windows-amd64-portable.zip from the releases page:

Expand-Archive slashsum-windows-amd64-portable.zip -DestinationPath .
cd slashsum-windows-amd64-portable
.\install.bat

Option 7: 🍎 macOS (Portable)

Download the portable package from the releases page:

tar -xzvf slashsum-darwin-amd64-portable.tar.gz
cd slashsum-darwin-amd64-portable
sudo ./install.sh

Option 8: 🔨 Build from source

Prerequisites: Rust toolchain (1.70+)

git clone https://github.com/NDXDeveloper/slashsum
cd slashsum
cargo build --release

The binary will be available at target/release/slashsum.

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🛠️ Usage

Basic Syntax

slashsum <FILE> [OPTIONS]

Options

Option	Description
--save	Save checksums to a .checksum file
-h, --help	Print help information
--version	Print version and license information

Examples

# Calculate checksums for a file
slashsum document.pdf

# Calculate and save results
slashsum large_file.iso --save
# Creates: large_file.iso.checksum

# Display help
slashsum --help

# Display version and license
slashsum --version

# Process multiple files (shell loop)
for f in *.iso; do slashsum "$f" --save; done

Output Format

File:     large_file.iso
Size:     4.68 GB (5033165312 bytes)
CRC32:    8d7be4e9
MD5:      a3b9d148c5f8d237f735a5d9795a2345
SHA1:     2aae6c35c94fcfb415dbe95f408b9ce91ee846ed
SHA256:   b94d27b9934d3e08a52e52d7da7dabfac484efe37a5380ee9088f7ace2efcde9
SHA512:   309ecc489c12d6eb4cc40f50c902f2b4d0ed77ee511a7c7a9bcd3ca86d4cd86f989dd35bc5ff499670da34255b45b0cfd830e81f605dcf7dc5542e93ae9cd76f
Time:     12.45s

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📈 Performance Benchmarks

🖥️ Test Environment

• CPU: AWS EC2 t2.xlarge (4 vCPUs)
• RAM: 16GB
• Storage: EBS SSD (gp3)
• OS: Ubuntu 22.04 LTS

📊 Results

File Size	Slashsum	sha256sum	md5sum	Improvement
100 MB	0.45s	0.28s	0.15s	5 hashes in ~1x time
1 GB	2.34s	2.10s	1.20s	5 hashes in ~1x time
10 GB	25.12s	22.50s	12.80s	5 hashes in ~1x time
50 GB	128.70s	115.00s	65.00s	5 hashes in ~1x time

💡 Key insight: Slashsum calculates 5 different checksums in approximately the same time it takes traditional tools to calculate just 1 checksum. This is because the bottleneck is disk I/O, not CPU.

🚀 Throughput

Storage Type	Read Speed	Slashsum Throughput
HDD (7200rpm)	~150 MB/s	~150 MB/s
SSD (SATA)	~550 MB/s	~500 MB/s
NVMe SSD	~3500 MB/s	~2000 MB/s

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⚖️ Comparison with Alternatives

Feature	Slashsum	sha256sum	md5sum	hashdeep
CRC32	Yes	No	No	No
MD5	Yes	No	Yes	Yes
SHA-1	Yes	No	No	Yes
SHA-256	Yes	Yes	No	Yes
SHA-512	Yes	No	No	No
All 5 at once	Yes	No	No	No
Parallel processing	Yes	No	No	Yes
Single binary	Yes	Yes	Yes	Yes
Cross-platform	Yes	Linux/macOS	Linux/macOS	Yes
Progress indicator	No	No	No	Yes
Recursive scan	No	No	No	Yes

✅ When to use Slashsum

• You need multiple checksums for the same file
• You want to verify file integrity with redundancy
• You're creating release artifacts that need multiple hashes
• You want one command instead of running 5 tools

⚠️ When to use alternatives

• You only need one specific hash
• You need to recursively scan directories (use hashdeep)
• You need a progress bar for very large files

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🧠 How It Works

┌─────────────────────────────────────────────────────────────────┐
│                         SLASHSUM                                │
├─────────────────────────────────────────────────────────────────┤
│                                                                 │
│   ┌─────────┐    ┌──────────────┐     ┌─────────────────────┐   │
│   │  File   │───>│   Reader     │────>│  Crossbeam Channel  │   │
│   │ (disk)  │    │ (1MB chunks) │     │   (broadcaster)     │   │
│   └─────────┘    └──────────────┘     └──────────┬──────────┘   │
│                                                  │              │
│                    ┌─────────────────────────────┼───────┐      │
│                    │                             │       │      │
│                    v                             v       v      │
│              ┌──────────┐  ┌──────────┐  ┌──────────┐   ...     │
│              │  CRC32   │  │   MD5    │  │  SHA-1   │           │
│              │ (thread) │  │ (thread) │  │ (thread) │           │
│              └────┬─────┘  └────┬─────┘  └────┬─────┘           │
│                   │             │             │                 │
│                   v             v             v                 │
│              ┌─────────────────────────────────────────────┐    │
│              │            Result Aggregator                │    │
│              └─────────────────────────────────────────────┘    │
│                                    │                            │
│                                    v                            │
│                             ┌────────────┐                      │
│                             │   Output   │                      │
│                             └────────────┘                      │
│                                                                 │
└─────────────────────────────────────────────────────────────────┘

⚙️ Processing Steps

1. 📖 File Reading: Buffered reading in 1MB chunks for optimal I/O
2. 📡 Data Distribution: Uses crossbeam channels to broadcast chunks to all hash workers
3. ⚡ Parallel Processing: Dedicated thread for each hash algorithm (5 threads)
4. 🔗 Result Aggregation: Waits for all threads to complete and collects results
5. 📝 Output Formatting: Human-readable sizes and standardized hash formats

🤔 Why 1MB chunks?

• ❌ Too small (4KB): High overhead from channel operations
• ❌ Too large (100MB): High memory usage, cache misses
• ✅ 1MB: Sweet spot balancing throughput and memory efficiency

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🔧 Technical Details

Property	Value
Binary size	~650 KB (Linux), ~700 KB (Windows)
Memory usage	~10-15 MB (5 threads × 1MB buffer + overhead)
Rust version	1.70+ (stable)
Architecture	x86_64 only
Dependencies	None (static binary)
Threads	5 (one per hash algorithm) + 1 (file reader)
Buffer size	1 MB per chunk
Channel capacity	1024 chunks

🖥️ Supported Platforms

Platform	Architecture	Format
🐧 Linux	x86_64	Binary, DEB, Snap, tar.gz
🪟 Windows	x86_64	EXE installer, ZIP portable
🍎 macOS	x86_64	tar.gz portable

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❓ FAQ

🤔 Why calculate 5 checksums instead of just one?

Different use cases require different algorithms:

• CRC32: Fast error detection, used in ZIP files
• MD5: Legacy compatibility, still widely used
• SHA-1: Git commits, some package managers
• SHA-256: Modern standard, security applications
• SHA-512: Maximum security, large file verification

Having all 5 ready saves time when you need to publish or verify files.

🚀 Why is Slashsum not much slower than single-hash tools?

Disk I/O is the bottleneck, not CPU. While reading the file once, all 5 hash algorithms process the data in parallel. The overhead of parallel processing is minimal compared to disk read time.

🎛️ Can I choose which algorithms to calculate?

Not currently. Slashsum always calculates all 5 checksums. This keeps the tool simple and ensures consistent output. Future versions may add algorithm selection.

✅ Does Slashsum verify checksums?

Not yet. Currently, Slashsum only calculates checksums. Verification mode (--verify) may be added in future versions.

💻 Why x86_64 only?

Cross-compilation for ARM and other architectures is planned but not yet implemented. You can build from source for other architectures if you have Rust installed.

🔒 Is it safe to use MD5/SHA-1?

For file integrity (detecting accidental corruption): ✅ Yes, they're fine. For security (detecting tampering): ⚠️ Use SHA-256 or SHA-512.

Slashsum provides both, so you can use the appropriate one for your needs.

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🗑️ Uninstall

🐧 Linux (Snap)

sudo snap remove slashsum

🐧 Linux (DEB)

sudo apt remove slashsum

🐧🍎 Linux/macOS (Portable)

# Using uninstall script
sudo ./uninstall.sh

# Or manually
sudo rm /usr/local/bin/slashsum

🪟 Windows (Installer)

• Settings > Apps > Slashsum > Uninstall
• Or: Control Panel > Programs > Uninstall

🪟 Windows (Portable)

# Using uninstall script
.\uninstall.bat

# Or manually delete from your PATH folder

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📚 Dependencies

• crossbeam-channel - High-performance multi-producer multi-consumer channels
• RustCrypto Hashes - Pure Rust cryptographic hash implementations
• crc - CRC32 calculation (IEEE 802.3 polynomial)

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🤝 Contributing

Contributions are welcome! Please read our guidelines before submitting.

• CONTRIBUTING.md - Contribution guidelines
• CODE_OF_CONDUCT.md - Code of conduct

How to contribute

1. Fork the repository
2. Create a feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'Add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

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📋 Changelog

See Releases for version history and release notes.

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👤 Author

Nicolas DEOUX

• Email: NDXDev@gmail.com
• LinkedIn: nicolas-deoux
• GitHub: NDXDeveloper

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📜 License

MIT License - See LICENSE for details.

Copyright (c) 2025-2026 Nicolas DEOUX

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software...

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Why "Slashsum"? Combination of "slash" (/) for file paths and "checksum" - because every good tool needs a catchy name!

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Happy hashing!

If you find this useful, a star is always appreciated.