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Properly define the on-chain handover protocol

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The new key publishing `Batch`s is more than sufficient.

Also uses the correct key to verify the published `Batch`s authenticity.
This commit is contained in:
Luke Parker
2023-10-10 23:55:59 -04:00
parent 1a0b4198ba
commit 13cbc99149
5 changed files with 55 additions and 36 deletions
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52
substrate/in-instructions/pallet/src/lib.rs
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@@ -80,29 +80,21 @@ pub mod pallet {
}
}
fn key_for_network<T: Config>(network: NetworkId) -> Result<Public, InvalidTransaction> {
// TODO: Get the latest session
let session = Session(0);
fn key_for_network<T: Config>(network: NetworkId) -> Result<(Session, Option<Public>, Option<Public>), InvalidTransaction> {
let session = ValidatorSets::<T>::session(network);
let mut set = ValidatorSet { session, network };
// TODO: If this session just set their keys, it'll invalidate any batches in the mempool
// Should there be a transitory period/future-set cut off?
if let Some(keys) = ValidatorSets::<T>::keys(set) {
Ok(keys.0)
} else {
// If this set hasn't set their keys yet, use the previous set's
if set.session.0 == 0 {
// Since there haven't been any keys set, no signature can legitimately exist
Err(InvalidTransaction::BadProof)?;
}
let latest = ValidatorSets::<T>::keys(set).map(|keys| keys.0);
let prior = if set.session.0 != 0 {
set.session.0 -= 1;
if let Some(keys) = ValidatorSets::<T>::keys(set) {
Ok(keys.0)
} else {
Err(InvalidTransaction::BadProof)?
}
ValidatorSets::<T>::keys(set).map(|keys| keys.0)
} else {
None
};
// If there's no keys set, then this must be an invalid signature
if prior.is_none() && latest.is_none() {
Err(InvalidTransaction::BadProof)?;
}
Ok((session, prior, latest))
}
#[pallet::call]
@@ -155,7 +147,7 @@ pub mod pallet {
};
let network = batch.batch.network;
let key = key_for_network::<T>(network)?;
let (current_session, prior, current) = key_for_network::<T>(network)?;
// verify the batch size
// TODO: Merge this encode with the one done by batch_message
@@ -164,10 +156,26 @@ pub mod pallet {
}
// verify the signature
if !key.verify(&batch_message(&batch.batch), &batch.signature) {
let batch_message = batch_message(&batch.batch);
// Check the prior key first since only a single `Batch` (the last one) will be when prior is
// Some yet prior wasn't the signing key
let valid_by_prior = if let Some(key) = prior {
key.verify(&batch_message, &batch.signature)
} else { false };
let valid = valid_by_prior || (if let Some(key) = current {
key.verify(&batch_message, &batch.signature)
} else { false });
if !valid {
Err(InvalidTransaction::BadProof)?;
}
// If it wasn't valid by the prior key, meaning it was valid by the current key, the current
// key is publishing `Batch`s. This should only happen once the current key has verified all
// `Batch`s published by the prior key, meaning they are accepting the hand-over.
if prior.is_some() && (!valid_by_prior) {
ValidatorSets::<T>::retire_session(network, Session(current_session.0 - 1));
}
// check that this validator set isn't publishing a batch more than once per block
let current_block = <frame_system::Pallet<T>>::block_number();
let last_block = LastBatchBlock::<T>::get(network).unwrap_or(Zero::zero());