Makes RemoveParticipantDueToDkg a voted-on event instead of a Provided.
This removes the requirement for offline parties to be able to fully validate
blame, yet unfortunately lets an dishonest supermajority have an honest node
label any arbitrary node as dishonest.
Corrects a variety of `.i(...)` calls which panicked when they shouldn't have.
Cleans up a couple no-longer-used storage values.
With a DKG removal comes a reduction in the amount of participants which was
ignored by re-attempts.
Now, we determine n/i based on the parties removed, and deterministically
obtain the context of who was removd.
* Schedule re-attempts and add a (not filled out) match statement to actually execute them
A comment explains the methodology. To copy it here:
"""
This is because we *always* re-attempt any protocol which had participation. That doesn't
mean we *should* re-attempt this protocol.
The alternatives were:
1) Note on-chain we completed a protocol, halting re-attempts upon 34%.
2) Vote on-chain to re-attempt a protocol.
This schema doesn't have any additional messages upon the success case (whereas
alternative #1 does) and doesn't have overhead (as alternative #2 does, sending votes and
then preprocesses. This only sends preprocesses).
"""
Any signing protocol which reaches sufficient participation will be
re-attempted until it no longer does.
* Have the Substrate scanner track DKG removals/completions for the Tributary code
* Don't keep trying to publish a participant removal if we've already set keys
* Pad out the re-attempt match a bit more
* Have CosignEvaluator reload from the DB
* Correctly schedule cosign re-attempts
* Actuall spawn new DKG removal attempts
* Use u32 for Batch ID in SubstrateSignableId, finish Batch re-attempt routing
The batch ID was an opaque [u8; 5] which also included the network, yet that's
redundant and unhelpful.
* Clarify a pair of TODOs in the coordinator
* Remove old TODO
* Final comment cleanup
* Correct usage of TARGET_BLOCK_TIME in reattempt scheduler
It's in ms and I assumed it was in s.
* Have coordinator tests drop BatchReattempts which aren't relevant yet may exist
* Bug fix and pointless oddity removal
We scheduled a re-attempt upon receiving 2/3rds of preprocesses and upon
receiving 2/3rds of shares, so any signing protocol could cause two re-attempts
(not one more).
The coordinator tests randomly generated the Batch ID since it was prior an
opaque byte array. While that didn't break the test, it was pointless and did
make the already-succeeded check before re-attempting impossible to hit.
* Add log statements, correct dead-lock in coordinator tests
* Increase pessimistic timeout on recv_message to compensate for tighter best-case timeouts
* Further bump timeout by a minute
AFAICT, GH failed by just a few seconds.
This also is worst-case in a single instance, making it fine to be decently long.
* Further further bump timeout due to lack of distinct error
* Move logic for evaluating if a cosign should occur to its own file
Cleans it up and makes it more robust.
* Have expected_next_batch return an error instead of retrying
While convenient to offer an error-free implementation, it potentially caused
very long lived lock acquisitions in handle_processor_message.
* Unify and clean DkgConfirmer and DkgRemoval
Does so via adding a new file for the common code, SigningProtocol.
Modifies from_cache to return the preprocess with the machine, as there's no
reason not to. Also removes an unused Result around the type.
Clarifies the security around deterministic nonces, removing them for
saved-to-disk cached preprocesses. The cached preprocesses are encrypted as the
DB is not a proper secret store.
Moves arguments always present in the protocol from function arguments into the
struct itself.
Removes the horribly ugly code in DkgRemoval, fixing multiple issues present
with it which would cause it to fail on use.
* Set SeraiBlockNumber in cosign.rs as it's used by the cosigning protocol
* Remove unnecessary Clone from lambdas in coordinator
* Remove the EventDb from Tributary scanner
We used per-Transaction DB TXNs so on error, we don't have to rescan the entire
block yet only the rest of it. We prevented scanning multiple transactions by
tracking which we already had.
This is over-engineered and not worth it.
* Implement borsh for HasEvents, removing the manual encoding
* Merge DkgConfirmer and DkgRemoval into signing_protocol.rs
Fixes a bug in DkgConfirmer which would cause it to improperly handle indexes
if any validator had multiple key shares.
* Strictly type DataSpecification's Label
* Correct threshold_i_map_to_keys_and_musig_i_map
It didn't include the participant's own index and accordingly was offset.
* Create TributaryBlockHandler
This struct contains all variables prior passed to handle_block and stops them
from being passed around again and again.
This also ensures fatal_slash is only called while handling a block, as needed
as it expects to operate under perfect consensus.
* Inline accumulate, store confirmation nonces with shares
Inlining accumulate makes sense due to the amount of data accumulate needed to
be passed.
Storing confirmation nonces with shares ensures that both are available or
neither. Prior, one could be yet the other may not have been (requiring an
assert in runtime to ensure we didn't bungle it somehow).
* Create helper functions for handling DkgRemoval/SubstrateSign/Sign Tributary TXs
* Move Label into SignData
All of our transactions which use SignData end up with the same common usage
pattern for Label, justifying this.
Removes 3 transactions, explicitly de-duplicating their handlers.
* Remove CurrentlyCompletingKeyPair for the non-contextual DkgKeyPair
* Remove the manual read/write for TributarySpec for borsh
This struct doesn't have any optimizations booned by the manual impl. Using
borsh reduces our scope.
* Use temporary variables to further minimize LoC in tributary handler
* Remove usage of tuples for non-trivial Tributary transactions
* Remove serde from dkg
serde could be used to deserialize intenrally inconsistent objects which could
lead to panics or faults.
The BorshDeserialize derives have been replaced with a manual implementation
which won't produce inconsistent objects.
* Abstract Future generics using new trait definitions in coordinator
* Move published_signed_transaction to tributary/mod.rs to reduce the size of main.rs
* Split coordinator/src/tributary/mod.rs into spec.rs and transaction.rs
Uses a full-fledged serai-abi to do so.
Removes use of UncheckedExtrinsic as a pointlessly (for us) length-prefixed
block with a more complicated signing algorithm than advantageous.
In the future, we should considering consolidating the various primitives
crates. I'm not convinced we benefit from one primitives crate per pallet.
* Update ValidatorSets with a remove_participant call
* Add DkgRemoval, a sign machine for producing the relevant MuSig signatures
* Don't use position-dependent u8s yet Public when removing validators from the DKG
* Add DkgRemovalPreprocess, DkgRemovalShares
Implementation is via a new publish_tributary_tx lambda.
This is code is a copy-pasted mess which will need to be cleaned up.
* Only allow non-removed validators to vote for removals
Otherwise, it's risked that the remaining validators fall below 67% of the
original set.
* Correct publish_serai_tx, which was prior publish_set_keys in practice
This mirrors how Provided TXs handle topics.
Now, instead of managing a global nonce stream, we can use items such as plan
IDs as topics.
This massively benefits re-attempts, as else we'd need a NOP TX to clear unused
nonces.
* Remove NetworkId from processor-messages
Because intent binds to the sender/receiver, it's not needed for intent.
The processor knows what the network is.
The coordinator knows which to use because it's sending this message to the
processor for that network.
Also removes the unused zeroize.
* ProcessorMessage::Completed use Session instead of key
* Move SubstrateSignId to Session
* Finish replacing key with session
* Add SignalsConfig to chain_spec
* Correct multiexp feature flagging for rand_core std
* Remove bincode for borsh
Replaces a non-canonical encoding with a canonical encoding which additionally
should be faster.
Also fixes an issue where we used bincode in transcripts where it cannot be
trusted.
This ended up fixing a myriad of other bugs observed, unfortunately.
Accordingly, it either has to be merged or the bug fixes from it must be ported
to a new PR.
* Make serde optional, minimize usage
* Make borsh an optional dependency of substrate/ crates
* Remove unused dependencies
* Use [u8; 64] where possible in the processor messages
* Correct borsh feature flagging
* Add a function to deterministically decide which Serai blocks should be co-signed
Has a 5 minute latency between co-signs, also used as the maximal latency
before a co-sign is started.
* Get all active tributaries we're in at a specific block
* Add and route CosignSubstrateBlock, a new provided TX
* Split queued cosigns per network
* Rename BatchSignId to SubstrateSignId
* Add SubstrateSignableId, a meta-type for either Batch or Block, and modularize around it
* Handle the CosignSubstrateBlock provided TX
* Revert substrate_signer.rs to develop (and patch to still work)
Due to SubstrateSigner moving when the prior multisig closes, yet cosigning
occurring with the most recent key, a single SubstrateSigner can be reused.
We could manage multiple SubstrateSigners, yet considering the much lower
specifications for cosigning, I'd rather treat it distinctly.
* Route cosigning through the processor
* Add note to rename SubstrateSigner post-PR
I don't want to do so now in order to preserve the diff's clarity.
* Implement cosign evaluation into the coordinator
* Get tests to compile
* Bug fixes, mark blocks without cosigners available as cosigned
* Correct the ID Batch preprocesses are saved under, add log statements
* Create a dedicated function to handle cosigns
* Correct the flow around Batch verification/queueing
Verifying `Batch`s could stall when a `Batch` was signed before its
predecessors/before the block it's contained in was cosigned (the latter being
inevitable as we can't sign a block containing a signed batch before signing
the batch).
Now, Batch verification happens on a distinct async task in order to not block
the handling of processor messages. This task is the sole caller of verify in
order to ensure last_verified_batch isn't unexpectedly mutated.
When the processor message handler needs to access it, or needs to queue a
Batch, it associates the DB TXN with a lock preventing the other task from
doing so.
This lock, as currently implemented, is a poor and inefficient design. It
should be modified to the pattern used for cosign management. Additionally, a
new primitive of a DB-backed channel may be immensely valuable.
Fixes a standing potential deadlock and a deadlock introduced with the
cosigning protocol.
* Working full-stack tests
After the last commit, this only required extending a timeout.
* Replace "co-sign" with "cosign" to make finding text easier
* Update the coordinator tests to support cosigning
* Inline prior_batch calculation to prevent panic on rotation
Noticed when doing a final review of the branch.
* chore: convert nonce_deicer to use create_db macro
* Restore pub NonceDecider
* Remove extraneous comma
I forgot to run git commit --amend on the prior commit :/
---------
Co-authored-by: Luke Parker <lukeparker5132@gmail.com>
* Have processor report errors during the DKG to the coordinator
* Add RemoveParticipant, InvalidDkgShare to coordinator
* Route DKG blame around coordinator
* Allow public construction of AdditionalBlameMachine
Necessary for upcoming work on handling DKG blame in the processor and
coordinator.
Additionally fixes a publicly reachable panic when commitments parsed with one
ThresholdParams are used in a machine using another set of ThresholdParams.
Renames InvalidProofOfKnowledge to InvalidCommitments.
* Remove unused error from dleq
* Implement support for VerifyBlame in the processor
* Have coordinator send the processor share message relevant to Blame
* Remove desync between processors reporting InvalidShare and ones reporting GeneratedKeyPair
* Route blame on sign between processor and coordinator
Doesn't yet act on it in coordinator.
* Move txn usage as needed for stable Rust to build
* Correct InvalidDkgShare serialization
* Update the coordinator to give key shares based on weight, not based on existence
Participants are now identified by their starting index. While this compiles,
the following is unimplemented:
1) A conversion for DKG `i` values. It assumes the threshold `i` values used
will be identical for the MuSig signature used to confirm the DKG.
2) Expansion from compressed values to full values before forwarding to the
processor.
* Add a fn to the DkgConfirmer to convert `i` values as needed
Also removes TODOs regarding Serai ensuring validator key uniqueness +
validity. The current infra achieves both.
* Have the Tributary DB track participation by shares, not by count
* Prevent a node from obtaining 34% of the maximum amount of key shares
This is actually mainly intended to set a bound on message sizes in the
coordinator. Message sizes are amplified by the amount of key shares held, so
setting an upper bound on said amount lets it determine constants. While that
upper bound could be 150, that'd be unreasonable and increase the potential for
DoS attacks.
* Correct the mechanism to detect if sufficient accumulation has occured
It used to check if the latest accumulation hit the required threshold. Now,
accumulations may jump past the required threshold. The required mechanism is
to check the threshold wasn't prior met and is now met.
* Finish updating the coordinator to handle a multiple key share per validator environment
* Adjust stategy re: preventing noce reuse in DKG Confirmer
* Add TODOs regarding dropped transactions, add possible TODO fix
* Update tests/coordinator
This doesn't add new multi-key-share tests, it solely updates the existing
single key-share tests to compile and run, with the necessary fixes to the
coordinator.
* Update processor key_gen to handle generating multiple key shares at once
* Update SubstrateSigner
* Update signer, clippy
* Update processor tests
* Update processor docker tests
Adds Event::SetRetired to validator-sets.
Emit TributaryRetired.
Replaces is_active_set, which made multiple network requests, with
is_retired_tributary, a DB read.
Performs most of the removals necessary upon TributaryRetired.
Still needs to clean up the actual Tributary/Tendermint tasks.
Prior, we only supported a single Tributary per network, and spawned a task to
handled Processor messages per Tributary. Now, we handle Processor messages per
network, yet we still only supported a single Tributary in that handling
function.
Now, when we handle a message, we load the Tributary which is relevant. Once we
know it, we ensure we have it (preventing race conditions), and then proceed.
We do need work to check if we should have a Tributary, or if we're not
participating. We also need to check if a Tributary has been retired, meaning
we shouldn't handle any transactions related to them, and to clean up retired
Tributaries.
It was a piece of duplicated data used to achieve context-less
de)serialization. This new Vec code is a bit tricker to first read, yet overall
clean and removes a potential fault.
Saves 2 bytes from DkgShares messages.
See prior commit message for more info.
With the plan for the batch sign ID to be just 5 bytes (potentially 4), this
does incur a +5 bytes cost compared to the ExternalBlock system *even in the
standard case*. The simplicity remains preferred at this time.
The initial TODO was simply to use one ExternalBlock per all batches in the
block. This would require publishing ExternalBlock after the last batch,
requiring knowing the last batch. While we could add such a pipeline, it'd
require:
1) Initial preprocesses using a distinct message from BatchPreprocess
2) An additional message sent after all BatchPreprocess are sent
Unfortunately, both would require tweaks to the SubstrateSigner which aren't
worth the complexity compared to the solution here, at least, not at this time.
While this will cause, if a Tributary is signing a block whose total batch data
exceeds 25 kB, to use multiple transactions which could be optimized out by
'better' local data pipelining, that's an extreme edge case. Given the temporal
nature of each Tributary, it's also an acceptable edge.
This does no longer achieve synchrony over external blocks accordingly. While
signed batches have synchrony, as they embed their block hash, batches being
signed don't have cryptographic synchrony on their contents. This means
validators who are eclipsed may produce invalid shares, as they sign a
different batch. This will be introduced in a follow-up commit.
They used &mut self to prevent execution at the same time. This uses a lock
over the channel to achieve the same security, without requiring a lock over
the entire tributary.
This fixes post-provided Provided transactions. sync_block waited for the TX to
be provided, yet it never would as sync_block held a mutable reference over the
entire Tributary, preventing any other read/write operations of any scope.
A timeout increased (bc2f23f72b) due to this bug
not being identified has been decreased back, thankfully.
Also shims in basic support for Completed, which was the WIP before this bug
was identified.
