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Jonas Resch edited this page Nov 27, 2025 · 1 revision

Frequently Asked Questions

Common questions about QuantHide.


General

What is steganography?

Steganography is the practice of hiding secret information within ordinary, non-secret data. Unlike encryption (which makes data unreadable), steganography hides the very existence of the secret.

Why "post-quantum"?

Current encryption like RSA and ECC will be broken by quantum computers using Shor's algorithm. QuantHide uses Kyber1024, a quantum-resistant algorithm selected by NIST, ensuring your secrets remain safe even in a post-quantum world.

Is QuantHide free?

Yes, QuantHide is completely free and open source under the MIT License.

Does QuantHide collect any data?

No. QuantHide runs entirely locally on your device. No data is ever sent to any server. No accounts, no analytics, no telemetry.


Security

How secure is QuantHide?

Very secure. QuantHide uses:

  • Kyber1024: NIST-approved post-quantum encryption (Level 5)
  • ChaCha20-Poly1305: Military-grade authenticated encryption
  • Argon2id: Memory-hard key derivation (64MB per attempt)

Can the hidden data be detected?

The encrypted data itself appears as random noise. However:

  • Basic visual inspection: No — changes are invisible
  • Statistical analysis: Unlikely with random padding
  • Advanced ML models: Possibly detect presence, but not content

What if I forget my password?

The data is lost forever. There's no recovery mechanism, no backdoor, no master key. Use a password manager.

Can someone prove I have hidden data?

With standard encoding: Potentially, through advanced analysis. With Decoy Mode: You can reveal plausible content while denying any other secrets exist.


Technical

What image formats are supported?

Input (cover images):

  • PNG ✅
  • JPEG ✅
  • WebP ✅

Output:

  • Always PNG (lossless, preserves hidden data)

How much data can I hide?

Approximately: (width × height × 3) ÷ 8 bytes

Image Size Capacity
1920×1080 ~760 KB
3840×2160 ~3 MB
4000×3000 ~4.3 MB

Does encoding visibly change the image?

No. QuantHide uses LSB (Least Significant Bit) encoding, modifying only the least important bit of each color channel. The changes are imperceptible to the human eye.

Can I hide files, not just text?

Yes! QuantHide can hide any file type up to the image's capacity.


Usage

Why does the output have to be PNG?

JPEG and WebP use lossy compression, which would destroy the hidden data. PNG is lossless, preserving every pixel exactly.

Can I upload the encoded image to social media?

Not recommended. Most social platforms re-compress images, which destroys the hidden data. Use direct sharing methods instead.

Can I edit the encoded image?

No. Any modification (cropping, resizing, filtering, format conversion) will destroy the hidden data.

What happens if I use the wrong password?

The decryption will fail, and you'll get an error message. The data remains intact in the image — you can try again with the correct password.


Troubleshooting

"Decoding failed" error

  • Wrong password
  • Image was modified/compressed after encoding
  • Image doesn't contain hidden data
  • Split decode: Missing one or more parts

Encoded image looks different

This shouldn't happen. If you notice visible changes:

  • Try a higher-resolution cover image
  • Use an image with more visual complexity
  • Report a bug if the issue persists

App won't start on macOS

Right-click the app → Open (first time only, to bypass Gatekeeper).

Split decode not working

  • Make sure you've loaded ALL parts
  • Parts must be from the same encoding session
  • Use the same password for all parts

Comparison

QuantHide vs OpenStego

Feature QuantHide OpenStego
Quantum-safe ✅ Kyber1024
Encryption ChaCha20-Poly1305 AES
Key derivation Argon2id (64MB) SHA
Decoy mode
Split encoding

QuantHide vs Steghide

Feature QuantHide Steghide
Quantum-safe
Encryption Modern 3DES (outdated)
GUI ✅ Modern ❌ CLI only
Active development ❌ (abandoned)

Contributing

How can I contribute?

  • Report bugs via GitHub Issues
  • Submit feature requests
  • Contribute code via Pull Requests
  • Help with documentation
  • Share QuantHide with others

I found a security vulnerability

Please report it responsibly. See SECURITY.md for instructions. Do NOT open a public issue.

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