Slash when accounts in transaction do not exist
Closed this issue · 7 comments
We need to add a condition to ensure that the coordinator gets slashed if the transaction contains an account which doesn't exist and hence it's impossible to create an Merkel proof for it
It should be possible to create merkle proofs for all indexes in the account tree. The tree should be initalized with 0 fro all leaves so you can always load an index at position x.
Yeah, that's possible.
Consider this:
- User signs a transaction with from index as 100 while the max index created was 50
- Coordinator submits the transaction
At the moment the processTx function tries to:
- Verify the public key is present via the PDA Merkle proof provided by the challenger
We need to find a way to somehow let the challenger indicate that the fromIndex doesn't exist and here's the MP that shows that the accountTree committed doesn't have a fromIndex mentioned in the transaction.
Agree you cannot have index gr8er than max index.
require(index >= max_index)
where max index as a variable we incrament every time a new address is added to the pda tree?
Yeah, we do have that variable but it's not part of the commitment. So it keeps changing.
One expensive way to deal with this would be, sending 2 PDA MP's which proves there exists 2 leaves with indexes n and n+1 where n is not zero while n+1 is zero. Thus proving n was the max_index
Yeah, we do have that variable but it's not part of the commitment. So it keeps changing.
It only incraments so there is no way for require(index >= max_index) to be true and then later false. index only gets bigger so if require(index >= max_index) is true then require(index+1 >= max_index)
We don't have to worry about this now. The public key Id will be passed into the MerkleTree.verify() as the path parameter, which will break nothing given all any possible path. It's also cryptographically impossible to create a valid proof out of a path outside of the tree. So no extra check required.
Can close this issue