Generating several random numbers in one transaction (Solidity)

Question

Is there a way to generate several random numbers in a single transaction? Let's suppose I have this code:

function example(uint _prop) public{
    while(random(100) < _prob){
      // Do something  
    }
}

The condition of the while loop depends on the random number chosen in each iteration. Is it possible to do this with VRF (Chainlink)? Or can only one random number be generated for each transaction?

For now I'm using this solution:

function random(uint _interval) internal returns (uint) {
    nonce++;
    return uint(keccak256(abi.encodePacked(block.difficulty, block.timestamp, nonce))) % _interval;
}

but I know this is not a random number... This serves my purpose, but it is not formal. I want to improve it.

See [this question](https://stackoverflow.com/questions/48848948/how-to-generate-a-random-number-in-solidity) or [this one](https://stackoverflow.com/questions/52467248/how-can-we-generate-multiple-random-number-in-ethereum). — pgSystemTester, Nov 25 '21 at 00:42

score 2 · Answer 1 · answered Nov 25 '21 at 00:58

2

What you'd want to do, is make a Chainlink Random number request and then use than number to "expand" to more random numbers, like so:

function expand(uint256 randomValue, uint256 n) public pure returns (uint256[] memory expandedValues) {
    expandedValues = new uint256[](n);
    for (uint256 i = 0; i < n; i++) {
        expandedValues[i] = uint256(keccak256(abi.encode(randomValue, i)));
    }
    return expandedValues;
}

Since we get the random number from a verifiably random location, we can then drop the number in this and get any number of random numbers after.

answered Nov 25 '21 at 00:58

Patrick Collins

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great solution is it safe ? – Amit Wagner Oct 02 '22 at 11:44
Chainlink VRF is safe to generate random numbers (and newer versions of VRF allow you to request many). But getting a random number without chainlink VRF is not safe. – Patrick Collins Oct 03 '22 at 12:51
yaa but generating new random numbers based on your solution (getting 1 random number from chainlink and then generating new ones) is it safe ? – Amit Wagner Oct 03 '22 at 13:53
If it's done in the same transaction as generating the original one - yes. Otherwise no. – Patrick Collins Oct 03 '22 at 13:58
1

thanks a lot!!!!!!!!!!! its will help me reduce a lot of gas as i need 60 random numbers and saving them on storage and then retrieve them is expansive – Amit Wagner Oct 03 '22 at 14:02

Generating several random numbers in one transaction (Solidity)

1 Answers1