Random number generator

[toxic beacon]

I need random numbers in smart contract. Previously I saw @zealous loom were suggesting
"As to your concrete question, you can safely rely on the entropy of the epoch seeds (see Mina.getNetworkState), which are protected by consensus and seed the VRF used for slot leader selection (can’t get any more secure than this)."
#1210200684922798090 message

I see this.network.stakingEpochData.seed field, but as I can understand it is updated once on epoche start.
Is there some random values per slot?

[prisma lynx]

I guess you want something that is not predictable before that block exists?

Otherwise just hash the staking epoch data plus the slot number

[toxic beacon]

Yes. The idea was that user send his transaction and in several blocks we call function that generate random for him using some data from block

We can't use block hash for that because it can be easily manipulated. But I saw the response with "entropy of the epoch seeds" and was interested if we can use that.

[zealous loom]

@toxic beacon combine them

[toxic beacon]

But it will be as easy to manipulate as just a block hash, isn't it?

[zealous loom]

Block ashes in mina are unpredictable due to the combination of the market activity, recorded inside of the block, as well as the epoch seed recorded for the entire epoch

[zealous loom]

Source any additional entropy thru interaction with the contract

[toxic beacon]

If block hashes are upredictable - why we can't just use them? I thought that the main problem with randomness form blockhash is that block producer can easily manipulate it. Why do we need stakingEpoch.seed?

[zealous loom]

You are correct with the problem, but the epoch seed combines all the entropy from individual block producers so no one party can manipulate.

[toxic beacon]

But if we do hash(epochSeed, blockHash), it as as easy to manipulate as just blockhash. And epochSeed is updated too rarely to use it by itself

[zealous loom]

This is why i suggest sourcing additional entropy by contract interaction; applying the same technique that Ouroboros itself uses but in your “appchain”

[toxic beacon]

Hmmmm,I need to explore more how Ouroboros do it. The problem with in-contract entropy, that users can influence the result of random, and it can lead to security issues. But maybe there is a way to do it secure

[valid trail]

Tagging @tall pasture as well, there is a team who will be focusing on this one - any input would be helpful.

[zealous loom]

There is a way to do it secure: monoid it together with the secure entropy that the protocol provides.

[tall pasture]

Hey, as @valid trail stated, there is another team who will get randomnes fromm Drand- Distributed Randomness Beacon. Regarding your question - Using the epoch and an additional 'random' number can work as well right ? I haven't thought about mathematical analysis of it but if you get get the data from epoch and also add somethings from user (not a manual input necessarily, but a signature that is again somehow created by user with a random message in the process) can work as increasing the entropy.

[toxic beacon]

It looks like I have a hell of a lot to read 😁

[zealous loom]

Yep, the other teams in the space need all the luck they can get.

If you haven’t thought about the mathematical analysis, keep your hands out of the code, and don’t ever ever ever put your money into a Mina smart contract.

[toxic beacon]

We are building a lottery game. So if we are using user input to generate random, the last user that would participate in it would be able to change random generation result, so his tikket would win.

[zealous loom]

The grinding problem.

[tall pasture]

Okay, i see now. I didn't know it was lottery gmae

[crystal swan]

is there a way to generate a random number but restricting it to a set of Field? e.g Field(1) .... Field(20)

[prisma lynx]

you mean, derive a number between 1 and 20 in a provable way from a seed?
or just, how to create a random number between 1 and 20 outside provable code?

[crystal swan]

both options so I understand and also figure out which is preferrable...thanks