feat(lib/babe): Submit BABE equivocation report (#2947)

- Added support for runtime functions `BabeGenerateKeyOwnershipProof` and `BabeSubmitReportEquivocationUnsignedExtrinsic`
- and report a babe equivocation report when it occurs

Issue #2853

dot/core/interfaces.go

@@ -45,6 +45,12 @@ type RuntimeInstance interface {
 	DecodeSessionKeys(enc []byte) ([]byte, error)
 	PaymentQueryInfo(ext []byte) (*types.RuntimeDispatchInfo, error)
 	CheckInherents()
+	BabeGenerateKeyOwnershipProof(slot uint64, authorityID [32]byte) (
+		types.OpaqueKeyOwnershipProof, error)
+	BabeSubmitReportEquivocationUnsignedExtrinsic(
+		equivocationProof types.BabeEquivocationProof,
+		keyOwnershipProof types.OpaqueKeyOwnershipProof,
+	) error
 	RandomSeed()
 	OffchainWorker()
 	GenerateSessionKeys()

dot/interfaces.go

@@ -64,6 +64,8 @@ type runtimeInterface interface {
 	DecodeSessionKeys(enc []byte) ([]byte, error)
 	PaymentQueryInfo(ext []byte) (*types.RuntimeDispatchInfo, error)
 	CheckInherents()
+	BabeGenerateKeyOwnershipProof(slot uint64, offenderPublicKey [32]byte) (types.OpaqueKeyOwnershipProof, error)
+	BabeSubmitReportEquivocationUnsignedExtrinsic(types.BabeEquivocationProof, types.OpaqueKeyOwnershipProof) error
 	RandomSeed()
 	OffchainWorker()
 	GenerateSessionKeys()

dot/rpc/modules/interfaces_test.go

@@ -33,6 +33,8 @@ type Runtime interface {
 	ExecuteBlock(block *types.Block) ([]byte, error)
 	DecodeSessionKeys(enc []byte) ([]byte, error)
 	PaymentQueryInfo(ext []byte) (*types.RuntimeDispatchInfo, error)
+	BabeGenerateKeyOwnershipProof(slot uint64, offenderPublicKey [32]byte) (types.OpaqueKeyOwnershipProof, error)
+	BabeSubmitReportEquivocationUnsignedExtrinsic(types.BabeEquivocationProof, types.OpaqueKeyOwnershipProof) error
 	CheckInherents()
 	RandomSeed()
 	OffchainWorker()

dot/state/interfaces.go

@@ -89,6 +89,8 @@ type Runtime interface {
 	DecodeSessionKeys(enc []byte) ([]byte, error)
 	PaymentQueryInfo(ext []byte) (*types.RuntimeDispatchInfo, error)
 	CheckInherents()
+	BabeGenerateKeyOwnershipProof(slot uint64, offenderPublicKey [32]byte) (types.OpaqueKeyOwnershipProof, error)
+	BabeSubmitReportEquivocationUnsignedExtrinsic(types.BabeEquivocationProof, types.OpaqueKeyOwnershipProof) error
 	RandomSeed()
 	OffchainWorker()
 	GenerateSessionKeys()

dot/types/equivocation.go

@@ -0,0 +1,32 @@
+// Copyright 2023 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package types
+
+import "github.com/ChainSafe/gossamer/lib/crypto/sr25519"
+
+// BabeEquivocationProof represents a babe equivocation proof.
+// An equivocation happens when a validator produces more than one block on the same slot.
+// The proof of equivocation are the given distinct headers that were signed by the validator
+// and which include the slot number.
+type BabeEquivocationProof struct {
+	// Offender is the public key of the equivocator.
+	Offender AuthorityID
+	// Slot at which the equivocation happened.
+	Slot uint64
+	// FirstHeader is the first header involved in the equivocation.
+	FirstHeader Header
+	// SecondHeader is the second header involved in the equivocation.
+	SecondHeader Header
+}
+
+// AuthorityID represents a babe authority identifier.
+type AuthorityID [sr25519.PublicKeyLength]byte
+
+// OpaqueKeyOwnershipProof is 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, implementers of the runtime API will have to make
+// sure that all usages of `OpaqueKeyOwnershipProof` refer to the same type.
+type OpaqueKeyOwnershipProof []byte

dot/types/equivocation_test.go

@@ -0,0 +1,30 @@
+// Copyright 2022 ChainSafe Systems (ON)
+// SPDX-License-Identifier: LGPL-3.0-only
+
+package types
+
+import (
+	"testing"
+
+	"github.com/ChainSafe/gossamer/lib/common"
+	"github.com/ChainSafe/gossamer/pkg/scale"
+	"github.com/stretchr/testify/require"
+)
+
+func TestEquivocationProof(t *testing.T) {
+	// To get these bytes run
+	// https://github.com/paritytech/substrate/blob/17c07af0b953b84dbe89341294e98e586f9b4591/frame/babe/src/tests.rs#L932
+	expectedEncoding := common.MustHexToBytes("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") //nolint:lll
+
+	decodedProof := BabeEquivocationProof{
+		FirstHeader:  *NewEmptyHeader(),
+		SecondHeader: *NewEmptyHeader(),
+	}
+
+	err := scale.Unmarshal(expectedEncoding, &decodedProof)
+	require.NoError(t, err)
+
+	actualEncoding, err := scale.Marshal(decodedProof)
+	require.NoError(t, err)
+	require.Equal(t, expectedEncoding, actualEncoding)
+}

lib/babe/errors.go

@@ -24,6 +24,9 @@ import (
 )
 
 var (
+	// ErrAuthIndexOutOfBound is returned when a authority index doesn't exist
+	ErrAuthIndexOutOfBound = errors.New("authority index doesn't exist")
+
 	// ErrBadSlotClaim is returned when a slot claim is invalid
 	ErrBadSlotClaim = errors.New("could not verify slot claim VRF proof")