Draw Console
Run an OCSA-certified draw. Every result is written permanently to the Polygon blockchain.
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Loading operator details...
OCSA Certified
Draw Verified
New Draw
Powered by Chainlink VRF · Polygon
Competition Details
This appears on the certificate exactly as written.
Ticket Range (Sold Tickets Only)
Operator (Pre-filled from your OCSA record)
Certificate PDF will be sent here automatically.
Drop your entry list here or click to browse
Excel, CSV or PDF · Your file is never uploaded · Hashing happens entirely in your browser
⚠ IMPORTANT – READ BEFORE HASHING
Hash your complete, final entry list only – the exact file you will publish publicly as proof of this draw. Hashing will fingerprint the state of your file at this precise moment in time. The fingerprint is permanent and immutable on the blockchain. Any change to the file after hashing – adding a row, deleting a ticket, correcting a single character – will produce a completely different hash that no longer matches your certificate.
⚠ The consequences cannot be overstated. If your published entry list does not match the hash on your certificate, it will appear to the world that the entry list was altered after the draw – by you, the operator. There are very few innocent explanations for this. Your reputation and the integrity of your draw could be permanently and publicly damaged — possibly beyond repair. Get the list right before you hash it.
Pricing: £2.50 per certified draw. If the winning number falls on an unsold ticket, each redraw costs £1.00 until a sold ticket is selected. The final winning draw is charged at £2.50.
Announcer Prompts
Waiting to start...
Press Run to begin. Prompts will appear here as the draw progresses.
Draw Log
Online Competition Standards Authority · Blockchain Draw Certificate
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Winning Ticket
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OCSA Certified
Blockchain Verified
| Entry list hash (SHA-256) | -- |
| Operator | -- |
| Chainlink request ID | -- |
| Transaction hash | -- |
| Block number | -- |
| Verify independently | -- |
How OCSA Certified Draws Work
The full process, documented. Security through transparency – not obscurity.
A draw system that requires you to trust the operator is not a draw system – it is a promise. OCSA was founded on the principle that promises are not enough. Every element of this process is documented here because none of it needs to be secret. The security does not live in the method. It lives in the mathematics. Publishing exactly how we work does not create a vulnerability. It eliminates one: the vulnerability of opacity. We are not asking anyone to trust OCSA. We are showing everyone exactly why they do not need to.
The small print in the big picture.
Production
The Real Process
What happens when the live Chainlink contract is active
This Demo
What This Demo Does
How the current version differs from production
Integrity
If Tampered Here
What breaks and why it cannot be hidden
1
Operator presses Run
The operator’s details are loaded from the OCSA member database. They enter the prize description and their sold ticket range. Nothing has happened on the blockchain yet.
1
Same Identical
The operator form, Capsule member data, and ticket range inputs work exactly as they will in production.
1
False ticket range submitted
Breaks at participant verification. Participants hold their own ticket numbers and can cross-reference against the operator’s published list. A manipulated range is detectable by anyone who downloaded the list before the draw.
2
Request written to Polygon
A signed transaction is sent to the OCSA smart contract at 0xB24C8D...2f92 on the Polygon mainnet. This costs a small amount of LINK – the cryptocurrency that pays Chainlink oracle nodes – and a small amount of MATIC, the native Polygon currency used to pay a transaction fee called gas. The transaction gets a permanent hash: a unique string of characters that identifies it on the blockchain forever. The winning number does not exist yet.
2
Block number is real Live
The demo polls the live Polygon blockchain and displays the current real block number. No transaction is sent. No LINK or MATIC is spent. LINK is the cryptocurrency that pays Chainlink oracle nodes for their work. MATIC is the native currency of the Polygon network, used to pay a small transaction fee – called gas – whenever anything is written to the blockchain. Both are handled automatically by OCSA as part of the certified draw service.
2
Fake transaction submitted
Breaks immediately. A fabricated transaction hash does not exist on Polygonscan. Any participant can paste the hash into polygonscan.com in seconds and confirm it is real or non-existent. There is nowhere to hide a fake transaction on a public blockchain.
3
Chainlink oracle network engages
A number of independent Chainlink oracle nodes each individually generate a random number and a cryptographic proof that it is genuinely random. This takes 30 to 90 seconds on Polygon. The winning number still does not exist. Nobody – including OCSA – can predict or influence the outcome at this point.
3
Number generated in browser Different
The winning number is generated immediately using crypto.getRandomValues() – your browser’s own cryptographic random number generator. It is genuinely random but it is generated on your computer, not by the Chainlink oracle network. The number already exists before the node animation starts.
3
Attempt to influence Chainlink output
Breaks cryptographically. Every Chainlink VRF response includes a mathematical proof that the number was generated correctly. The Polygon network verifies this proof automatically before accepting the transaction. A manipulated proof fails verification and is rejected by the network entirely. The request simply does not fulfil.
4
Consensus and result written to chain
Once enough nodes agree, Chainlink writes the result back to the OCSA smart contract in a second on-chain transaction. This is the exact moment the winning number comes into existence. It is generated by a decentralised network outside the control of OCSA, the operator, or any third party.
4
Node animation is illustrative Different
The six node panels show what the real oracle network process looks like. In the demo, the nodes are not doing real work – the animation runs for a realistic duration to demonstrate what the production experience looks and feels like. The hash strings flickering inside each node panel are randomly generated in the browser, not real cryptographic proofs.
4
Attempt to alter the result before it is written
Not possible. The Chainlink network writes the result directly to the smart contract. Neither OCSA nor the operator has the ability to intercept or modify this transaction. The smart contract accepts input only from the authorised Chainlink VRF coordinator address. Any other address attempting to write a result is rejected automatically.
5
Result read and certificate issued
The console polls the blockchain every 2 seconds until the result arrives. The winning number, Chainlink request ID, transaction hash and block number are all read directly from the chain. The certificate is generated using this real on-chain data and published permanently to the OCSA verified draws register.
5
Transaction hash is stub Different
The transaction hash and Chainlink request ID shown on the certificate are randomly generated strings. They do not exist on the blockchain. The Polygonscan link will not resolve.
5
Certificate altered after issue
Breaks at independent verification. The transaction hash on the certificate links directly to a permanent, unalterable record on Polygonscan. If the winning number on the certificate does not match the number in that transaction, the discrepancy is immediately visible to anyone who checks. The blockchain record always wins.
6
Independent verification
Anyone can take the transaction hash from the certificate and look it up on Polygonscan – a free public blockchain explorer, like a search engine for the Polygon network. The Chainlink VRF fulfillment event is visible in the transaction data, and the random number it produced is right there for anyone to read. The result is permanently and publicly verifiable by anyone with internet access, forever – regardless of what happens to OCSA or the operator.
6
Certificate format is production-ready Identical
The certificate layout, fields, timestamps, operator details and proof table are exactly as they will appear in production. Only the blockchain data will be real.
6
There is no step 6 attack
Once the result is on the Polygon blockchain it is permanent. Altering a blockchain record would require rewriting every subsequent block on a global decentralised network simultaneously – a task requiring more computational power than currently exists on Earth. This is not a theoretical security guarantee. It is a mathematical one.