> For the complete documentation index, see [llms.txt](https://ovro.gitbook.io/ovro-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ovro.gitbook.io/ovro-docs/protocol/randomness.md).

# Randomness

OVRO uses the **drand League of Entropy** `evmnet` beacon, a public randomness network run by independent organisations. Each beacon round is a threshold **BLS signature**, and OVRO verifies it **inside the smart contract**.

## How a draw works

1. When a round closes, the randomness contract **commits to a future beacon round**, about one minute ahead. That value does not exist yet, so nobody (players, the team or the automation) can know or predict it.
2. When drand publishes that round, **anyone** submits the signature.
3. The contract verifies the BLS signature against drand's public key using Ethereum's BN254 precompiles. A wrong or forged value is rejected.
4. The verified signature is hashed with the request id, and the result selects the winning ticket.

## Why this is fair

| Property          | Guarantee                                                                                                                                                                          |
| ----------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| Unpredictable     | The committed beacon round is in the future at the moment of commitment.                                                                                                           |
| Unbiasable        | BLS signatures are unique: there is exactly one valid value per round, and the submitter cannot choose it.                                                                         |
| Verifiable        | Anyone can recompute the draw from the public beacon and the on-chain request.                                                                                                     |
| No trusted server | HTTP relays only transport the beacon; the contract checks the cryptography itself. OVRO uses several independent relays (`api.drand.sh`, `api2`, `api3`, `drand.cloudflare.com`). |
| One shot          | Each request can be fulfilled once. Late, duplicate or unauthorized callbacks are rejected.                                                                                        |

## Why drand

Chainlink VRF and Pyth Entropy are not deployed on Robinhood Chain. drand `evmnet` was designed specifically for on-chain verification on EVM chains, and it needs no subscription or trusted operator.

**Trust assumption:** a threshold of drand League of Entropy members does not collude.

## Timing

* The draw commits to a beacon **20 rounds ahead**, about 60 seconds.
* If no beacon is delivered within **1 hour**, anyone can request new randomness.
* If a round is still not drawn **7 days** after it closed, anyone can cancel it and every ticket is refunded.

## Verify a draw yourself

The full step-by-step recomputation, with explorer calls and `cast` commands, is on [Verify a draw](/ovro-docs/protocol/verify-a-draw.md).


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