Ultra.io Docs

RNG Contract ​

Overview ​

ultra.rng contract provides a secure and verifiable random number generation service for Ultra blockchain applications. It uses BLS12-381 cryptographic signatures to ensure the randomness cannot be manipulated by any party, including the oracle.

For Ultra, the RNG service is deployed under account ultra.rng and provides a decentralized solution for generating random numbers that can be used in games, lotteries, and other applications requiring randomness.

Contract features ​

1 - Request Random Numbers ​

  • Any smart contract can request a random number by calling the requestrand action with a unique seed and association ID.
  • The contract maintains a job queue and assigns unique job IDs to each request.
  • Seeds must be unique and cannot be zero to ensure proper randomness.

2 - Oracle Service Integration ​

  • The Ultra oracle service monitors the RNG contract for new random number requests.
  • When a request is detected, the oracle service generates a cryptographically secure random value.
  • The oracle service calls the setrand action with the generated random value and BLS12-381 signature.
  • The oracle service also manages the public key by calling setpubkey when needed.

3 - Verifiable Randomness ​

  • Uses BLS12-381 cryptographic signatures to ensure the randomness cannot be manipulated.
  • The oracle signs the random value with a private key, and the signature can be verified on-chain.
  • This prevents both the oracle and any other party from predicting or manipulating the random numbers.

4 - Callback System ​

  • When the oracle service calls setrand, the RNG contract verifies the signature and calls the receiverand action on the requesting contract.
  • The callback includes the association ID and the generated random number.
  • This allows contracts to receive random numbers asynchronously.

5 - Administrative Controls ​

  • The oracle service can set the public key used for signature verification via setpubkey.
  • DApps can be banned or unbanned from using the RNG service.
  • Jobs can be killed to clean up the job queue.
  • All administrative actions can be disabled through the contract manager.

6 - Security Features ​

  • Banned accounts are silently ignored when requesting random numbers.
  • Seeds are tracked to prevent reuse.
  • Job IDs are unique and incrementing.
  • All actions require proper authentication.

Integration ​

To use the RNG contract in your smart contract:

  1. Implement a receiverand action that accepts uint64_t assoc_id and uint64_t random_value parameters.
  2. Call requestrand with a unique seed and association ID to request a random number.
  3. Handle the callback in your receiverand action to use the generated random number.

For a complete step-by-step tutorial on integrating the RNG contract into your smart contract, see How to Integrate RNG in Smart Contracts.

The RNG contract provides a secure, decentralized solution for random number generation that can be trusted for critical applications like gaming, lotteries, and other use cases requiring verifiable randomness.