OpenRandom provides a way for generating pseudo random numbers using external data sources and can be used in applications where randomness is important (games, lottery e.t.c). Random based on hashing of combined chainlink round's price feed data and hash of request block. Chainlink feed provides price data by different roundIds - core idea is to use it as part for randomness
Getting random
Getting random number consists of two steps: "request" and "result". Each request has requestId and will have one result random value.
Both steps are separated in time and executed by different transactions. There can be many random numbers requests in one transaction.
Step 1 Request
Request can be done calling _requestRandom() functon, returns value is unique requestId. Each request aims to be resolved after responseRoundId come.
Step 2 Result
Result must be done calling _fillResponse(uint256 requestId) function. This function reads request parameter, request chainlink feed data with exact roundId. Recieved data used for getting random value and write results into request structure for use and proof.
Concept explanation
hash(
requestId #1,
response at 344 (343+roundDelta) price 18001.1
block #3 date 1680874160
App requestId #1 blockhash(block #3)
Layer _requestRandom() )
(user) | _fillResponse()
| |
| |
V V
block # ------3-----------4-------------5-------------6-----------7-----------8------------9---
chainlink ------*-------------------------*-------------------------*------------------------*---
round # 343 344 345 346
price 18000.0 18001.1 18002.9 18002.7
date 1680872934 1680874160 1680894231 1680917954npx hardhat test