Public Records on the blockchain

English Education
1

Good day to all.
It was suggested to me to look into using the Cardano blockchain to use as a platform for creating a public record for Notices and other lawful filings.
I know how to obtain ADA and stake it, and that’s about it.

How does someone ‘upload’ documents to the blockchain to create a secure public record?

2 Likes
2

Hello. That is an excellent and classic use case for blockchain technology.

There is a fundamental distinction to make that will clarify the process for you: you do not upload the document (the file itself) to the blockchain.

Blockchain as Notary, Not Storage

Think of the Cardano blockchain as an immutable public notary, not as a file storage system like Google Drive.

Storing entire files (like a PDF or DOCX) directly “on-chain” would be prohibitively expensive and incredibly inefficient. The transaction fees are related to the data size, and it would cause “blockchain bloat,” as every node in the entire network would be forced to store your specific document forever.

The “Hash” is the Proof

Instead of storing the file, you store a unique cryptographic “fingerprint” of that file. This is called a hash (e.g., an SHA-256 hash).

The process is this:

  1. You take your legal document (the “Notice”).
  2. You run it through a hashing function on your local machine. This function outputs a small, unique string of characters (e.g., b3a4c...f1d0).
  3. This hash is tiny (e.g., 32 or 64 bytes) but unique to your document. If anything changes in that document—even a single comma—the hash will change completely.
  4. You then create a transaction on Cardano and embed this hash inside its metadata.

The result: You now have a public, permanent, and time-stamped record proving that your specific document (represented by that hash) existed at that exact moment. You have “anchored” your document to the blockchain.

So, Where Does the Document Go?

This brings up the obvious question: if the file isn’t on the blockchain, how do people see it?

This is where decentralized storage solutions like IPFS (InterPlanetary File System) come in. IPFS is a peer-to-peer network designed to store files permanently.

The complete workflow looks like this:

  1. Upload to IPFS: You upload your legal document to IPFS. IPFS gives you back a unique identifier for that file, called a CID (which is also a hash).
  2. Anchor to Cardano: You create a Cardano transaction and put that IPFS CID (or the document’s hash) into the transaction’s metadata field.
  3. Verification: Now, anyone can look at your transaction on the Cardano blockchain, find the CID in the metadata, and use that CID to retrieve the original document from the IPFS network. They can then re-hash the document themselves to prove it’s the exact one you notarized.

Your Next Steps

You don’t necessarily need a complex smart contract for this. Your next step is to research how to create and submit a Cardano transaction with metadata. There are several tools, services, and libraries in the ecosystem that can help you do this without needing to be a developer. Look for terms like “Cardano data anchoring” or “Cardano notarization service.”

1 Like