How it works
Four steps from draw request to independently verified result
1
Operator runs a draw
Before the draw starts, the OCSA draw mechanism generates a SHA-256 fingerprint of the operator's entry list directly in their browser. The file never leaves their computer. That fingerprint is embedded permanently in the blockchain certificate – proving the list was not altered after the draw.
2
Chainlink generates randomness
Our smart contract sends a request to Chainlink's decentralised oracle network. The winning number does not exist yet. It is created at the moment of fulfilment using unpredictable blockchain data. A cryptographic proof is generated simultaneously and verified on the Polygon blockchain before the result can be used by anyone. It is mathematically impossible to predict or influence it.
3
Result written to blockchain
The winning ticket number and its cryptographic proof are written permanently to the Polygon blockchain the moment they are generated. This happens before any application – including ours – can use the result. The record is immutable and publicly visible on Polygonscan. It will be there for as long as humanity has need for the blockchain.
4
Certificate issued instantly
Your certificate is generated instantly and emailed to you. It is published automatically to the OCSA Public Draw Register, where anyone can search for it and verify the result using the transaction hash. The entry list hash on the certificate can also be used to verify that the operator's published entry list was not altered after the draw. No login required. The proof is permanently public and on the chain forever.
What a certified draw certificate looks like
Every completed draw produces a certificate like this one
Online Competition Standards Authority · Blockchain Draw Certificate
OCSA-2026-04-22-0001
Winning ticket
4827361
from 9,000,000 tickets
Lamborghini Huracan EVO — April 2026
Blockchain verified
Chainlink request ID
98471625837461928374651029384756
Transaction hash
0x3f8a2c91d4e7b05f6a1c3d9e2b7f4a8c5d1e3f9b...
Block number
58,247,391
Verify independently
polygonscan.com/tx/0x3f8a... ↗
This result was generated by Chainlink VRF and written permanently to the Polygon blockchain. It cannot be altered by OCSA, the operator, or any third party. The transaction hash above is your independent proof — no trust in OCSA is required to verify this draw.
Public draw register
Every certified draw published here automatically, permanently
Why this matters
What sets OCSA Certified Draws apart from standard random number generators
Genuinely independent
The random number is generated by Chainlink's decentralised oracle network. OCSA cannot influence, predict, or alter any result. Neither can the operator.
Publicly verifiable
Every result is published to the Polygon blockchain. Anyone with internet access can independently verify any draw using the transaction hash on Polygonscan.
Permanent record
Blockchain records cannot be altered, deleted, or fabricated. Every OCSA draw result is preserved permanently, regardless of what happens to OCSA or the operator.
DCMS Code compliant
The DCMS Voluntary Code requires "verifiably random and auditable" draw processes. Chainlink VRF is the industry standard for provably fair, independently auditable randomness.
A certificate every draw
Every completed draw produces its own signed, timestamped OCSA certificate. Not an annual audit. Not a sticker. Proof for this draw, on this date, at this time – in your hand.
Player confidence
Winners, entrants and sceptics can verify any draw result independently. No login required. No trust in OCSA required. The blockchain is the proof.
Ready to run certified draws?
OCSA Certified Draw is available to OCSA-certified operators. Certification starts at £75/month. Each draw costs £2.50 and produces an independently verifiable blockchain certificate automatically.
Contact OCSA to get startedTry the Demo