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lib.rs
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// This file is part of Substrate.
// Copyright (C) Parity Technologies (UK) Ltd.
// SPDX-License-Identifier: Apache-2.0
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#![cfg_attr(not(feature = "std"), no_std)]
#![warn(missing_docs)]
//! Primitives for BEEFY protocol.
//!
//! The crate contains shared data types used by BEEFY protocol and documentation (in a form of
//! code) for building a BEEFY light client.
//!
//! BEEFY is a gadget that runs alongside another finality gadget (for instance GRANDPA).
//! For simplicity (and the initially intended use case) the documentation says GRANDPA in places
//! where a more abstract "Finality Gadget" term could be used, but there is no reason why BEEFY
//! wouldn't run with some other finality scheme.
//! BEEFY validator set is supposed to be tracking the Finality Gadget validator set, but note that
//! it will use a different set of keys. For Polkadot use case we plan to use `secp256k1` for BEEFY,
//! while GRANDPA uses `ed25519`.
mod commitment;
mod payload;
pub mod mmr;
pub mod witness;
/// Test utilities
#[cfg(feature = "std")]
pub mod test_utils;
pub use commitment::{Commitment, SignedCommitment, VersionedFinalityProof};
pub use payload::{known_payloads, BeefyPayloadId, Payload, PayloadProvider};
use codec::{Codec, Decode, Encode};
use core::fmt::{Debug, Display};
use scale_info::TypeInfo;
use sp_application_crypto::{AppCrypto, AppPublic, ByteArray, RuntimeAppPublic};
use sp_core::H256;
use sp_runtime::traits::{Hash, Keccak256, NumberFor};
use sp_std::prelude::*;
/// Key type for BEEFY module.
pub const KEY_TYPE: sp_core::crypto::KeyTypeId = sp_application_crypto::key_types::BEEFY;
/// Trait representing BEEFY authority id, including custom signature verification.
///
/// Accepts custom hashing fn for the message and custom convertor fn for the signer.
pub trait BeefyAuthorityId<MsgHash: Hash>: RuntimeAppPublic {
/// Verify a signature.
///
/// Return `true` if signature over `msg` is valid for this id.
fn verify(&self, signature: &<Self as RuntimeAppPublic>::Signature, msg: &[u8]) -> bool;
}
/// Hasher used for BEEFY signatures.
pub type BeefySignatureHasher = sp_runtime::traits::Keccak256;
/// A trait bound which lists all traits which are required to be implemented by
/// a BEEFY AuthorityId type in order to be able to be used in BEEFY Keystore
pub trait AuthorityIdBound:
Codec
+ Debug
+ Clone
+ AsRef<[u8]>
+ ByteArray
+ AppPublic
+ AppCrypto
+ RuntimeAppPublic
+ Display
+ BeefyAuthorityId<BeefySignatureHasher>
{
}
/// BEEFY cryptographic types for ECDSA crypto
///
/// This module basically introduces four crypto types:
/// - `ecdsa_crypto::Pair`
/// - `ecdsa_crypto::Public`
/// - `ecdsa_crypto::Signature`
/// - `ecdsa_crypto::AuthorityId`
///
/// Your code should use the above types as concrete types for all crypto related
/// functionality.
pub mod ecdsa_crypto {
use super::{AuthorityIdBound, BeefyAuthorityId, Hash, RuntimeAppPublic, KEY_TYPE};
use sp_application_crypto::{app_crypto, ecdsa};
use sp_core::crypto::Wraps;
app_crypto!(ecdsa, KEY_TYPE);
/// Identity of a BEEFY authority using ECDSA as its crypto.
pub type AuthorityId = Public;
/// Signature for a BEEFY authority using ECDSA as its crypto.
pub type AuthoritySignature = Signature;
impl<MsgHash: Hash> BeefyAuthorityId<MsgHash> for AuthorityId
where
<MsgHash as Hash>::Output: Into<[u8; 32]>,
{
fn verify(&self, signature: &<Self as RuntimeAppPublic>::Signature, msg: &[u8]) -> bool {
let msg_hash = <MsgHash as Hash>::hash(msg).into();
match sp_io::crypto::secp256k1_ecdsa_recover_compressed(
signature.as_inner_ref().as_ref(),
&msg_hash,
) {
Ok(raw_pubkey) => raw_pubkey.as_ref() == AsRef::<[u8]>::as_ref(self),
_ => false,
}
}
}
impl AuthorityIdBound for AuthorityId {}
}
/// BEEFY cryptographic types for BLS crypto
///
/// This module basically introduces four crypto types:
/// - `bls_crypto::Pair`
/// - `bls_crypto::Public`
/// - `bls_crypto::Signature`
/// - `bls_crypto::AuthorityId`
///
/// Your code should use the above types as concrete types for all crypto related
/// functionality.
#[cfg(feature = "bls-experimental")]
pub mod bls_crypto {
use super::{AuthorityIdBound, BeefyAuthorityId, Hash, RuntimeAppPublic, KEY_TYPE};
use sp_application_crypto::{app_crypto, bls377};
use sp_core::{bls377::Pair as BlsPair, crypto::Wraps, Pair as _};
app_crypto!(bls377, KEY_TYPE);
/// Identity of a BEEFY authority using BLS as its crypto.
pub type AuthorityId = Public;
/// Signature for a BEEFY authority using BLS as its crypto.
pub type AuthoritySignature = Signature;
impl<MsgHash: Hash> BeefyAuthorityId<MsgHash> for AuthorityId
where
<MsgHash as Hash>::Output: Into<[u8; 32]>,
{
fn verify(&self, signature: &<Self as RuntimeAppPublic>::Signature, msg: &[u8]) -> bool {
// `w3f-bls` library uses IETF hashing standard and as such does not expose
// a choice of hash-to-field function.
// We are directly calling into the library to avoid introducing new host call.
// and because BeefyAuthorityId::verify is being called in the runtime so we don't have
BlsPair::verify(signature.as_inner_ref(), msg, self.as_inner_ref())
}
}
impl AuthorityIdBound for AuthorityId {}
}
/// BEEFY cryptographic types for (ECDSA,BLS) crypto pair
///
/// This module basically introduces four crypto types:
/// - `ecdsa_bls_crypto::Pair`
/// - `ecdsa_bls_crypto::Public`
/// - `ecdsa_bls_crypto::Signature`
/// - `ecdsa_bls_crypto::AuthorityId`
///
/// Your code should use the above types as concrete types for all crypto related
/// functionality.
#[cfg(feature = "bls-experimental")]
pub mod ecdsa_bls_crypto {
use super::{AuthorityIdBound, BeefyAuthorityId, Hash, RuntimeAppPublic, KEY_TYPE};
use sp_application_crypto::{app_crypto, ecdsa_bls377};
use sp_core::{crypto::Wraps, ecdsa_bls377::Pair as EcdsaBlsPair};
app_crypto!(ecdsa_bls377, KEY_TYPE);
/// Identity of a BEEFY authority using (ECDSA,BLS) as its crypto.
pub type AuthorityId = Public;
/// Signature for a BEEFY authority using (ECDSA,BLS) as its crypto.
pub type AuthoritySignature = Signature;
impl<H> BeefyAuthorityId<H> for AuthorityId
where
H: Hash,
H::Output: Into<[u8; 32]>,
{
fn verify(&self, signature: &<Self as RuntimeAppPublic>::Signature, msg: &[u8]) -> bool {
// We can not simply call
// `EcdsaBlsPair::verify(signature.as_inner_ref(), msg, self.as_inner_ref())`
// because that invokes ECDSA default verification which perfoms Blake2b hash
// which we don't want. This is because ECDSA signatures are meant to be verified
// on Ethereum network where Keccak hasher is significantly cheaper than Blake2b.
// See Figure 3 of [OnSc21](https://www.scitepress.org/Papers/2021/106066/106066.pdf)
// for comparison.
EcdsaBlsPair::verify_with_hasher::<H>(
signature.as_inner_ref(),
msg,
self.as_inner_ref(),
)
}
}
impl AuthorityIdBound for AuthorityId {}
}
/// The `ConsensusEngineId` of BEEFY.
pub const BEEFY_ENGINE_ID: sp_runtime::ConsensusEngineId = *b"BEEF";
/// Authority set id starts with zero at BEEFY pallet genesis.
pub const GENESIS_AUTHORITY_SET_ID: u64 = 0;
/// A typedef for validator set id.
pub type ValidatorSetId = u64;
/// A set of BEEFY authorities, a.k.a. validators.
#[derive(Decode, Encode, Debug, PartialEq, Clone, TypeInfo)]
pub struct ValidatorSet<AuthorityId> {
/// Public keys of the validator set elements
validators: Vec<AuthorityId>,
/// Identifier of the validator set
id: ValidatorSetId,
}
impl<AuthorityId> ValidatorSet<AuthorityId> {
/// Return a validator set with the given validators and set id.
pub fn new<I>(validators: I, id: ValidatorSetId) -> Option<Self>
where
I: IntoIterator<Item = AuthorityId>,
{
let validators: Vec<AuthorityId> = validators.into_iter().collect();
if validators.is_empty() {
// No validators; the set would be empty.
None
} else {
Some(Self { validators, id })
}
}
/// Return a reference to the vec of validators.
pub fn validators(&self) -> &[AuthorityId] {
&self.validators
}
/// Return the validator set id.
pub fn id(&self) -> ValidatorSetId {
self.id
}
/// Return the number of validators in the set.
pub fn len(&self) -> usize {
self.validators.len()
}
}
/// The index of an authority.
pub type AuthorityIndex = u32;
/// The Hashing used within MMR.
pub type MmrHashing = Keccak256;
/// The type used to represent an MMR root hash.
pub type MmrRootHash = H256;
/// A consensus log item for BEEFY.
#[derive(Decode, Encode, TypeInfo)]
pub enum ConsensusLog<AuthorityId: Codec> {
/// The authorities have changed.
#[codec(index = 1)]
AuthoritiesChange(ValidatorSet<AuthorityId>),
/// Disable the authority with given index.
#[codec(index = 2)]
OnDisabled(AuthorityIndex),
/// MMR root hash.
#[codec(index = 3)]
MmrRoot(MmrRootHash),
}
/// BEEFY vote message.
///
/// A vote message is a direct vote created by a BEEFY node on every voting round
/// and is gossiped to its peers.
// TODO: Remove `Signature` generic type, instead get it from `Id::Signature`.
#[derive(Clone, Debug, Decode, Encode, PartialEq, TypeInfo)]
pub struct VoteMessage<Number, Id, Signature> {
/// Commit to information extracted from a finalized block
pub commitment: Commitment<Number>,
/// Node authority id
pub id: Id,
/// Node signature
pub signature: Signature,
}
/// Proof of voter misbehavior on a given set id. Misbehavior/equivocation in
/// BEEFY happens when a voter votes on the same round/block for different payloads.
/// Proving is achieved by collecting the signed commitments of conflicting votes.
#[derive(Clone, Debug, Decode, Encode, PartialEq, TypeInfo)]
pub struct EquivocationProof<Number, Id, Signature> {
/// The first vote in the equivocation.
pub first: VoteMessage<Number, Id, Signature>,
/// The second vote in the equivocation.
pub second: VoteMessage<Number, Id, Signature>,
}
impl<Number, Id, Signature> EquivocationProof<Number, Id, Signature> {
/// Returns the authority id of the equivocator.
pub fn offender_id(&self) -> &Id {
&self.first.id
}
/// Returns the round number at which the equivocation occurred.
pub fn round_number(&self) -> &Number {
&self.first.commitment.block_number
}
/// Returns the set id at which the equivocation occurred.
pub fn set_id(&self) -> ValidatorSetId {
self.first.commitment.validator_set_id
}
}
/// Check a commitment signature by encoding the commitment and
/// verifying the provided signature using the expected authority id.
pub fn check_commitment_signature<Number, Id, MsgHash>(
commitment: &Commitment<Number>,
authority_id: &Id,
signature: &<Id as RuntimeAppPublic>::Signature,
) -> bool
where
Id: BeefyAuthorityId<MsgHash>,
Number: Clone + Encode + PartialEq,
MsgHash: Hash,
{
let encoded_commitment = commitment.encode();
BeefyAuthorityId::<MsgHash>::verify(authority_id, signature, &encoded_commitment)
}
/// Verifies the equivocation proof by making sure that both votes target
/// different blocks and that its signatures are valid.
pub fn check_equivocation_proof<Number, Id, MsgHash>(
report: &EquivocationProof<Number, Id, <Id as RuntimeAppPublic>::Signature>,
) -> bool
where
Id: BeefyAuthorityId<MsgHash> + PartialEq,
Number: Clone + Encode + PartialEq,
MsgHash: Hash,
{
let first = &report.first;
let second = &report.second;
// if votes
// come from different authorities,
// are for different rounds,
// have different validator set ids,
// or both votes have the same commitment,
// --> the equivocation is invalid.
if first.id != second.id ||
first.commitment.block_number != second.commitment.block_number ||
first.commitment.validator_set_id != second.commitment.validator_set_id ||
first.commitment.payload == second.commitment.payload
{
return false
}
// check signatures on both votes are valid
let valid_first = check_commitment_signature(&first.commitment, &first.id, &first.signature);
let valid_second =
check_commitment_signature(&second.commitment, &second.id, &second.signature);
return valid_first && valid_second
}
/// New BEEFY validator set notification hook.
pub trait OnNewValidatorSet<AuthorityId> {
/// Function called by the pallet when BEEFY validator set changes.
fn on_new_validator_set(
validator_set: &ValidatorSet<AuthorityId>,
next_validator_set: &ValidatorSet<AuthorityId>,
);
}
/// No-op implementation of [OnNewValidatorSet].
impl<AuthorityId> OnNewValidatorSet<AuthorityId> for () {
fn on_new_validator_set(_: &ValidatorSet<AuthorityId>, _: &ValidatorSet<AuthorityId>) {}
}
/// An opaque type used to represent the key ownership proof at the runtime API
/// boundary. The inner value is an encoded representation of the actual key
/// ownership proof which will be parameterized when defining the runtime. At
/// the runtime API boundary this type is unknown and as such we keep this
/// opaque representation, implementors of the runtime API will have to make
/// sure that all usages of `OpaqueKeyOwnershipProof` refer to the same type.
#[derive(Decode, Encode, PartialEq, TypeInfo)]
pub struct OpaqueKeyOwnershipProof(Vec<u8>);
impl OpaqueKeyOwnershipProof {
/// Create a new `OpaqueKeyOwnershipProof` using the given encoded
/// representation.
pub fn new(inner: Vec<u8>) -> OpaqueKeyOwnershipProof {
OpaqueKeyOwnershipProof(inner)
}
/// Try to decode this `OpaqueKeyOwnershipProof` into the given concrete key
/// ownership proof type.
pub fn decode<T: Decode>(self) -> Option<T> {
codec::Decode::decode(&mut &self.0[..]).ok()
}
}
sp_api::decl_runtime_apis! {
/// API necessary for BEEFY voters.
#[api_version(3)]
pub trait BeefyApi<AuthorityId> where
AuthorityId : Codec + RuntimeAppPublic,
{
/// Return the block number where BEEFY consensus is enabled/started
fn beefy_genesis() -> Option<NumberFor<Block>>;
/// Return the current active BEEFY validator set
fn validator_set() -> Option<ValidatorSet<AuthorityId>>;
/// Submits an unsigned extrinsic to report an equivocation. The caller
/// must provide the equivocation proof and a key ownership proof
/// (should be obtained using `generate_key_ownership_proof`). The
/// extrinsic will be unsigned and should only be accepted for local
/// authorship (not to be broadcast to the network). This method returns
/// `None` when creation of the extrinsic fails, e.g. if equivocation
/// reporting is disabled for the given runtime (i.e. this method is
/// hardcoded to return `None`). Only useful in an offchain context.
fn submit_report_equivocation_unsigned_extrinsic(
equivocation_proof:
EquivocationProof<NumberFor<Block>, AuthorityId, <AuthorityId as RuntimeAppPublic>::Signature>,
key_owner_proof: OpaqueKeyOwnershipProof,
) -> Option<()>;
/// Generates a proof of key ownership for the given authority in the
/// given set. An example usage of this module is coupled with the
/// session historical module to prove that a given authority key is
/// tied to a given staking identity during a specific session. Proofs
/// of key ownership are necessary for submitting equivocation reports.
/// NOTE: even though the API takes a `set_id` as parameter the current
/// implementations ignores this parameter and instead relies on this
/// method being called at the correct block height, i.e. any point at
/// which the given set id is live on-chain. Future implementations will
/// instead use indexed data through an offchain worker, not requiring
/// older states to be available.
fn generate_key_ownership_proof(
set_id: ValidatorSetId,
authority_id: AuthorityId,
) -> Option<OpaqueKeyOwnershipProof>;
}
}
#[cfg(test)]
mod tests {
use super::*;
use sp_application_crypto::ecdsa::{self, Public};
use sp_core::crypto::{Pair, Wraps};
use sp_crypto_hashing::{blake2_256, keccak_256};
use sp_runtime::traits::{BlakeTwo256, Keccak256};
#[test]
fn validator_set() {
// Empty set not allowed.
assert_eq!(ValidatorSet::<Public>::new(vec![], 0), None);
let alice = ecdsa::Pair::from_string("//Alice", None).unwrap();
let set_id = 0;
let validators = ValidatorSet::<Public>::new(vec![alice.public()], set_id).unwrap();
assert_eq!(validators.id(), set_id);
assert_eq!(validators.validators(), &vec![alice.public()]);
}
#[test]
fn ecdsa_beefy_verify_works() {
let msg = &b"test-message"[..];
let (pair, _) = ecdsa_crypto::Pair::generate();
let keccak_256_signature: ecdsa_crypto::Signature =
pair.as_inner_ref().sign_prehashed(&keccak_256(msg)).into();
let blake2_256_signature: ecdsa_crypto::Signature =
pair.as_inner_ref().sign_prehashed(&blake2_256(msg)).into();
// Verification works if same hashing function is used when signing and verifying.
assert!(BeefyAuthorityId::<Keccak256>::verify(&pair.public(), &keccak_256_signature, msg));
assert!(BeefyAuthorityId::<BlakeTwo256>::verify(
&pair.public(),
&blake2_256_signature,
msg
));
// Verification fails if distinct hashing functions are used when signing and verifying.
assert!(!BeefyAuthorityId::<Keccak256>::verify(&pair.public(), &blake2_256_signature, msg));
assert!(!BeefyAuthorityId::<BlakeTwo256>::verify(
&pair.public(),
&keccak_256_signature,
msg
));
// Other public key doesn't work
let (other_pair, _) = ecdsa_crypto::Pair::generate();
assert!(!BeefyAuthorityId::<Keccak256>::verify(
&other_pair.public(),
&keccak_256_signature,
msg,
));
assert!(!BeefyAuthorityId::<BlakeTwo256>::verify(
&other_pair.public(),
&blake2_256_signature,
msg,
));
}
#[test]
#[cfg(feature = "bls-experimental")]
fn bls_beefy_verify_works() {
let msg = &b"test-message"[..];
let (pair, _) = bls_crypto::Pair::generate();
let signature: bls_crypto::Signature = pair.as_inner_ref().sign(&msg).into();
// Verification works if same hashing function is used when signing and verifying.
assert!(BeefyAuthorityId::<Keccak256>::verify(&pair.public(), &signature, msg));
// Other public key doesn't work
let (other_pair, _) = bls_crypto::Pair::generate();
assert!(!BeefyAuthorityId::<Keccak256>::verify(&other_pair.public(), &signature, msg,));
}
#[test]
#[cfg(feature = "bls-experimental")]
fn ecdsa_bls_beefy_verify_works() {
let msg = &b"test-message"[..];
let (pair, _) = ecdsa_bls_crypto::Pair::generate();
let signature: ecdsa_bls_crypto::Signature =
pair.as_inner_ref().sign_with_hasher::<Keccak256>(&msg).into();
// Verification works if same hashing function is used when signing and verifying.
assert!(BeefyAuthorityId::<Keccak256>::verify(&pair.public(), &signature, msg));
// Verification doesn't work if we verify function provided by pair_crypto implementation
assert!(!ecdsa_bls_crypto::Pair::verify(&signature, msg, &pair.public()));
// Other public key doesn't work
let (other_pair, _) = ecdsa_bls_crypto::Pair::generate();
assert!(!BeefyAuthorityId::<Keccak256>::verify(&other_pair.public(), &signature, msg,));
}
}