WitnetRandomness Contract
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The , also known as the ยซWitnet Randomness Oracleยป, is the easiest and most convenient way to generate EVM-agnostic and realiable randomness for your smart contracts.
The Witnet Foundation sponsors a pre-deployed instance of WitnetRandomness
in practically all the .
While the WitnetRandomness
contract internally uses an instance of the low-level WitnetRequestRandomness
, this contract implements also the whole request/resolution asynchronous flow involved in the resolution of a data request in the context of the Witnet side-chain.
Moreover, the same instance can be safely and concurrently used by any number of indepent applications running within the same EVM-chain.
And therefore, depending on the time-response constraints of your own app, the Witnet Randomness Oracle may become the cheapest EVM-agnostic mechanism to generate reliable randomness in the whole crypto arena (๐ฃ).
In a nutshell, by using a WitnetRandomness
you just need to:
Eventually, care for requesting and paying for new randomness at any given time: see randomize() payable
.
Eventually, fetching a randomness value generated by Witnet after any given block number: see isRandomized(uint256)
and getRandomnessAfter(uint256)
.
As simple as that ;-)
The WitnetRandomness
contract is not owned, so anyone is actually allowed to either request new randomness (i.e. randomize()
), or get previously solved randomness from storage (i.e. isRandomized(uint _blockNumber)
, getRandomnessAfter(uint _blockNumber)
).
Besides, you or your contract will be able to request for new randomness (i.e. randomize() payable
), even if other previous randomness requests (either coming from you, or other apps) were still pending to be solved.
The WitnetRandomness
contract is Clonable
, which means that you, or your contract, may cheaply create your own cloned copy as a means to gain ownership of the self-contained WitnetRequestRandomness
contract. Only the owner of a cloned copy will be allowed to change the witnessing parameters of the low-level Randomness Request.
The WitnetRandomness
contract provides the random(uint32 _range, uint256 _nonce, uint256 _block)
and random(uint32 _range, uint256 _nonce, bytes32 _seed)
helper functions.
Most of all, the WitnetRandomness
contract guarantees that the received randomness is the one requested for a given block number, or the subsequent randomness request posted after the given block if there was none posted back then, or if the ones posted after that got reverted for whatever reason at the Witnet side-chain level.
This logic alone protects the Witnet Randomness Oracle against front-running attacks from mallicious miners at the EVM-chain level (๐ฃ).
Once you call on randomize() payable
, you should not allow any change in your smart contract state that alters the outcome of whatever the requested randomness is planned to be used for.
This back door of letting the WitnetRandomness
operator modify the underlying witnessing parameters of the randomness request, is left open as to provide a means for adapting to eventual high-load situations within the Witnet oracle's side-chain.
While the WitnetRandomness
contract is not owned, the self-contained WitnetRequestRandomness
instance it is (i.e. ). This enables the operator of aWitnetRandomness
instance to eventually update the witnessing parameters of the underlying low-level Randomenss Request that gets posted to the Witnet side-chain.
The RAD bytecode of the self-contained WitnetRequestRandomness
instance (accesible via the ), will foerever remain immutable, though.