QDN: The Power of Decentralized Data Hosting

The Qortal Data Network (QDN) is a decentralized hosting network that allows the transmission of any type of data via peer-to-peer communication.

It’s secured by the Qortal blockchain, and in a moment, you’ll see why that matters.'

How data is usually stored and shared (centralized model)

1. You upload a video to a centralized platform.

2. The platform either stores the file on its own servers or uses a third-party storage provider such as AWS.

This model has major drawbacks:

• For users: The platform can reject your content at any time.

• For platforms: Third-party storage providers can refuse to host certain files. Building your own storage infrastructure is costly and complex.

How QDN changes everything

On QDN, there’s no single controlling server and no dependency on a third party’s approval.

Data is stored across a global network of peers, and file integrity is enforced by the blockchain.

This means your content can’t be arbitrarily denied, and hosting costs and complexity are dramatically reduced.

How does QDN Work - a simplified illustration

How QDN Publishes and Shares Files

When you publish a video (or any data) on QDN, the file is first chunked into smaller pieces and stored locally on your file system. It is not uploaded to a central server.

The hash of your file, along with key details like who the owner is, is stored on the blockchain.

Your file only leaves your computer when another user requests it. At that point, the chunks are replicated from your system to the requester’s system, and they, in turn, become a peer. When a third user requests the file, they can fetch chunks from you, the second user, and any other peers who already have them.

Example: Bob Fetches Your_video_file.mp4

1. Bob asks his peers: Bob sends a request to all his peers, asking if they have any chunks of the file.

2. Peers respond: You, one of Bob’s peers, checks their local storage:

• If you have chunks, you reply with what you have.

• If you don’t have chunks, your node asks your peers if they have any.

In this new example, you (the original publisher) and Peter both have the file chunks.

3. Bob’s peer map. Bob now knows:

• Peer 1: You have all 4 chunks.

• Peer 2: John doesn’t have chunks himself, but his peer Peter does (all 4 chunks).

4. Chunk downloading:

• Chunk 1 → from you ✅

• Chunk 2 → from John (who fetches it from Peter) ✅

• Chunk 3 → from you ✅

• Chunk 4 → from John ❌ (fetch failed) → retried from you ✅

Rebuilding and Verifying the File

Once Bob has all 4 chunks:

1. The chunks are joined back into a single file.

2. The combined file’s hash is compared with the blockchain hash.

   • If they match → VALIDATED ✅

   • If they don’t match → file is discarded ❌

3. The validated file is decrypted and unzipped.

4. The complete file is ready to use.

5. Bob now stores both the full file and its individual chunks.

6. Bob becomes a peer for this file, just like you, and Peter.

How requesting chunks works on QDN

Why a blockchain for a p2p data network?

When accessing data, you need to be sure of two things:

1. Ownership: Who actually owns the data.

2. Integrity: Whether the data you download is exactly what was intended.

The blockchain acts as a decentralized, tamper-resistant source of truth for both.

Without it, any peer could claim that Your_video_file.mp4 belongs to someone else.

With it, ownership records are cryptographically verified and cannot be forged.

The blockchain also stores the hash of the QDN resource (the file). This ensures that when you download chunks from multiple peers and reassemble them, you can verify the final file matches the hash recorded on-chain.

If the reconstructed file’s hash doesn’t match the blockchain entry, the file is rejected, preventing you from using corrupted or malicious data.