eth/protocols/wit, consensus/bor: WIT2 — BP-signed witness announcements with transitive relay and pre-import serving

accounts/accounts.go

@@ -37,10 +37,11 @@
 }
 
 const (
 	MimetypeDataWithValidator = "data/validator"
 	MimetypeTypedData         = "data/typed"
 	MimetypeClique            = "application/x-clique-header"
 	MimetypeBor               = "application/x-bor-header"
+	MimetypeBorWitnessAnnounce = "application/x-bor-wit2-announce"
 	MimetypeTextPlain         = "text/plain"
 )
 

consensus/bor/bor.go

@@ -1510,6 +1510,42 @@ func Sign(signFn SignerFn, signer common.Address, header *types.Header, c *param
 	return nil
 }
 
+// SignBytes signs the supplied preimage bytes under a context-specific
+// mimetype using the engine's currently authorized signer. The mimetype is the
+// domain tag the underlying signer (clef, keystore) sees, so callers MUST pass
+// a context-specific value (e.g. accounts.MimetypeBorWitnessAnnounce) and
+// never reuse accounts.MimetypeBor outside of header sealing — that would let
+// a signature produced here be replayed as a block-seal signature on any
+// header BorRLP that hashes to the same digest.
+//
+// Callers pass the unhashed preimage; the wallet's SignData implementation
+// applies keccak256 once before signing. Verifiers must independently hash
+// the same preimage and ecrecover against the resulting digest.
+func (c *Bor) SignBytes(mimetype string, digest []byte) (signer common.Address, sig []byte, err error) {
+	if mimetype == "" || mimetype == accounts.MimetypeBor {
+		return common.Address{}, nil, errors.New("bor: SignBytes requires a non-empty, non-header mimetype")
+	}
+	current := c.authorizedSigner.Load()
+	if current == nil || current.signer == (common.Address{}) {
+		return common.Address{}, nil, errors.New("bor: no authorized signer configured")
+	}
+	sig, err = current.signFn(accounts.Account{Address: current.signer}, mimetype, digest)
+	if err != nil {
+		return common.Address{}, nil, err
+	}
+	return current.signer, sig, nil
+}
+
+// CurrentSigner returns the address of the currently authorized signer, or
+// the zero address if none has been configured.
+func (c *Bor) CurrentSigner() common.Address {
+	current := c.authorizedSigner.Load()
+	if current == nil {
+		return common.Address{}
+	}
+	return current.signer
+}
+
 // CalcDifficulty is the difficulty adjustment algorithm. It returns the difficulty
 // that a new block should have based on the previous blocks in the chain and the
 // current signer.

consensus/bor/signbytes_test.go

@@ -0,0 +1,70 @@
+package bor
+
+import (
+	"bytes"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/accounts"
+	"github.com/ethereum/go-ethereum/common"
+)
+
+// TestSignBytesForwardsMimetype is the regression for the wit2 announce
+// signing path's external-signer compatibility: bor.SignBytes must hand the
+// caller-supplied mimetype to the configured signer untouched. Operators
+// configuring Clef whitelist a specific string ("application/x-bor-wit2-
+// announce"); if SignBytes ever rewrote, lower-cased, or stripped that, the
+// signer would either reject the request or sign under a different domain.
+//
+// The test captures the (mimetype, payload) the wallet sees and asserts both
+// match exactly what the caller passed.
+func TestSignBytesForwardsMimetype(t *testing.T) {
+	bor := &Bor{}
+	addr := common.HexToAddress("0x1234")
+
+	var (
+		gotMimetype string
+		gotPayload  []byte
+	)
+	bor.Authorize(addr, func(_ accounts.Account, mimetype string, data []byte) ([]byte, error) {
+		gotMimetype = mimetype
+		gotPayload = append([]byte(nil), data...)
+		return make([]byte, 65), nil
+	})
+
+	preimage := []byte("wit2-announce-preimage")
+	signer, sig, err := bor.SignBytes(accounts.MimetypeBorWitnessAnnounce, preimage)
+	if err != nil {
+		t.Fatalf("SignBytes: %v", err)
+	}
+	if signer != addr {
+		t.Fatalf("signer addr mismatch: got %s want %s", signer, addr)
+	}
+	if len(sig) != 65 {
+		t.Fatalf("expected 65-byte signature, got %d", len(sig))
+	}
+	if gotMimetype != accounts.MimetypeBorWitnessAnnounce {
+		t.Fatalf("mimetype not forwarded literally: got %q want %q",
+			gotMimetype, accounts.MimetypeBorWitnessAnnounce)
+	}
+	if !bytes.Equal(gotPayload, preimage) {
+		t.Fatalf("payload not forwarded literally: got %x want %x", gotPayload, preimage)
+	}
+}
+
+// TestSignBytesRejectsHeaderMimetype guards against accidental cross-context
+// reuse: callers must never pass MimetypeBor (header sealing) into SignBytes,
+// since that would let an announce signature replay as a block-seal.
+func TestSignBytesRejectsHeaderMimetype(t *testing.T) {
+	bor := &Bor{}
+	bor.Authorize(common.HexToAddress("0x1234"), func(accounts.Account, string, []byte) ([]byte, error) {
+		t.Fatal("signFn must not be reached for rejected mimetype")
+		return nil, nil
+	})
+
+	if _, _, err := bor.SignBytes("", []byte{0x01}); err == nil {
+		t.Fatal("empty mimetype must be rejected")
+	}
+	if _, _, err := bor.SignBytes(accounts.MimetypeBor, []byte{0x01}); err == nil {
+		t.Fatal("MimetypeBor must be rejected to prevent header-seal replay")
+	}
+}

core/stateless/encoding.go

@@ -17,7 +17,9 @@
 package stateless
 
 import (
+	"bytes"
 	"io"
+	"sort"
 
 	"github.com/ethereum/go-ethereum/common/hexutil"
 	"github.com/ethereum/go-ethereum/core/types"
@@ -84,19 +86,29 @@ func (w *Witness) fromExtWitness(ext *ExtWitness) error {
 // EncodeRLP serializes a witness as RLP using the canonical BorWitness 3-field
 // format. Only state trie nodes are encoded; contract bytecodes are not
 // included in the wire format.
+//
+// State entries are sorted lexicographically before encoding so the output is
+// byte-identical for any two witnesses with the same logical contents. Without
+// this, Go's randomized map iteration would produce different bytes per call,
+// breaking any code that hashes the encoded witness for content addressing —
+// notably the WIT2 BP-signed witness hash, which is computed by both producer
+// and verifiers and must match exactly.
 func (w *Witness) EncodeRLP(wr io.Writer) error {
 	w.lock.RLock()
 	defer w.lock.RUnlock()
 
-	bw := &BorWitness{
-		Context: w.context,
-		Headers: w.Headers,
-		State:   make([][]byte, 0, len(w.State)),
-	}
+	state := make([][]byte, 0, len(w.State))
 	for node := range w.State {
-		bw.State = append(bw.State, []byte(node))
+		state = append(state, []byte(node))
 	}
-	return rlp.Encode(wr, bw)
+	sort.Slice(state, func(i, j int) bool {
+		return bytes.Compare(state[i], state[j]) < 0
+	})
+	return rlp.Encode(wr, &BorWitness{
+		Context: w.context,
+		Headers: w.Headers,
+		State:   state,
+	})
 }
 
 // DecodeRLP decodes a witness from RLP. It first attempts the canonical

core/stateless/encoding_test.go

@@ -180,3 +180,62 @@ func TestRoundtrip_BorWitnessFormat(t *testing.T) {
 		t.Errorf("Codes should be empty after BorWitness roundtrip, got %d", len(decoded.Codes))
 	}
 }
+
+// TestEncodeRLP_DeterministicAcrossInsertionOrder is the regression test for
+// the WIT2 byte-blame model. State entries arrive via a Go map, whose
+// iteration order is randomised, so without sorting in EncodeRLP two
+// witnesses with identical logical content would encode to different bytes
+// and hash differently. Receivers verifying response bytes against the BP-
+// signed witness hash would falsely drop honest peers.
+func TestEncodeRLP_DeterministicAcrossInsertionOrder(t *testing.T) {
+	const N = 64
+	nodes := make([][]byte, N)
+	for i := 0; i < N; i++ {
+		nodes[i] = []byte{byte(i), byte(i ^ 0x5a), byte(i ^ 0xa5)}
+	}
+
+	makeWitness := func(insertionOrder []int) *Witness {
+		w := &Witness{
+			Headers: []*types.Header{{Number: big.NewInt(1)}},
+			Codes:   make(map[string]struct{}),
+			State:   make(map[string]struct{}, len(insertionOrder)),
+		}
+		w.context = &types.Header{Number: big.NewInt(2)}
+		for _, i := range insertionOrder {
+			w.State[string(nodes[i])] = struct{}{}
+		}
+		return w
+	}
+
+	encode := func(w *Witness) []byte {
+		raw, err := rlp.EncodeToBytes(w)
+		if err != nil {
+			t.Fatalf("encode: %v", err)
+		}
+		return raw
+	}
+
+	forward := make([]int, N)
+	for i := range forward {
+		forward[i] = i
+	}
+	reverse := make([]int, N)
+	for i := range reverse {
+		reverse[i] = N - 1 - i
+	}
+
+	wForward := makeWitness(forward)
+	wReverse := makeWitness(reverse)
+	if got, want := encode(wForward), encode(wReverse); string(got) != string(want) {
+		t.Fatalf("EncodeRLP must be deterministic across map insertion orders; got divergent bytes (%d vs %d)", len(got), len(want))
+	}
+
+	// Re-encoding the same witness multiple times must also yield identical
+	// bytes, even though Go map iteration is fresh each call.
+	first := encode(wForward)
+	for i := 0; i < 5; i++ {
+		if string(encode(wForward)) != string(first) {
+			t.Fatalf("repeat encode call %d differs from first", i)
+		}
+	}
+}

core/stateless/witness_bench_test.go

@@ -0,0 +1,110 @@
+package stateless
+
+import (
+	"crypto/rand"
+	"fmt"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// BenchmarkWitnessEncodeRLP measures the cost of EncodeRLP, which sorts
+// state nodes lexicographically before serialization. Surfaces regressions if
+// the comparator changes (e.g. swapping bytes.Compare for an allocating
+// alternative). Synthetic 50 MiB witness with realistic node sizes.
+func BenchmarkWitnessEncodeRLP(b *testing.B) {
+	for _, sizeMiB := range []int{1, 15, 50} {
+		w := buildSyntheticWitness(sizeMiB<<20, 256)
+		b.Run(fmt.Sprintf("%dMiB", sizeMiB), func(b *testing.B) {
+			b.ReportAllocs()
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				if err := w.EncodeRLP(discardWriter{}); err != nil {
+					b.Fatalf("encode: %v", err)
+				}
+			}
+		})
+	}
+}
+
+type discardWriter struct{}
+
+func (discardWriter) Write(p []byte) (int, error) { return len(p), nil }
+
+// BenchmarkWitnessKeccakBySize measures the throughput of keccak256 over a
+// pre-allocated witness-sized buffer. This is the cost the producer pays to
+// compute WitnessHash on the WIT2 announce path (and the cost a relayer or
+// requester pays to verify response bytes against the BP-signed WitnessHash).
+//
+// Run with `go test -bench=BenchmarkWitnessKeccakBySize ./core/stateless/`.
+// b.SetBytes lets `go test -benchmem` print throughput in MB/s alongside ns/op,
+// which is what we actually want to know — the absolute size of any one
+// witness varies, but per-byte cost scales linearly.
+func BenchmarkWitnessKeccakBySize(b *testing.B) {
+	for _, sizeMiB := range []int{1, 5, 15, 30, 50} {
+		size := sizeMiB << 20
+		buf := make([]byte, size)
+		if _, err := rand.Read(buf); err != nil {
+			b.Fatalf("rand: %v", err)
+		}
+		b.Run(fmt.Sprintf("%dMiB", sizeMiB), func(b *testing.B) {
+			b.SetBytes(int64(size))
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				_ = crypto.Keccak256Hash(buf)
+			}
+		})
+	}
+}
+
+// BenchmarkWitnessAnnounceSign measures the marginal ECDSA cost of signing the
+// 32-byte announcement digest, independent of witness size. This isolates the
+// secp256k1 sign cost from the keccak cost so a single number per platform is
+// directly comparable to libsecp256k1 microbenchmarks.
+func BenchmarkWitnessAnnounceSign(b *testing.B) {
+	key, err := crypto.GenerateKey()
+	if err != nil {
+		b.Fatalf("key: %v", err)
+	}
+	digest := make([]byte, 32)
+	if _, err := rand.Read(digest); err != nil {
+		b.Fatalf("rand: %v", err)
+	}
+	b.ResetTimer()
+	for i := 0; i < b.N; i++ {
+		if _, err := crypto.Sign(digest, key); err != nil {
+			b.Fatalf("sign: %v", err)
+		}
+	}
+}
+
+// BenchmarkWitnessHashAndSignCombined measures the realistic producer-side
+// cost of the WIT2 announce path: keccak256 over witness bytes followed by
+// ECDSA sign over the (small) signing digest. This is the latency the BP
+// adds before emitting a signed announce. Compare against the ~500ms-per-hop
+// savings: as long as this stays well under the savings, the change is a
+// net win even at 50 MiB witnesses.
+func BenchmarkWitnessHashAndSignCombined(b *testing.B) {
+	key, err := crypto.GenerateKey()
+	if err != nil {
+		b.Fatalf("key: %v", err)
+	}
+	for _, sizeMiB := range []int{1, 5, 15, 30, 50} {
+		size := sizeMiB << 20
+		buf := make([]byte, size)
+		if _, err := rand.Read(buf); err != nil {
+			b.Fatalf("rand: %v", err)
+		}
+		b.Run(fmt.Sprintf("%dMiB", sizeMiB), func(b *testing.B) {
+			b.SetBytes(int64(size))
+			b.ResetTimer()
+			for i := 0; i < b.N; i++ {
+				witnessHash := crypto.Keccak256Hash(buf)
+				digest := crypto.Keccak256Hash(witnessHash[:], []byte{0x01, 0x02, 0x03, 0x04})
+				if _, err := crypto.Sign(digest[:], key); err != nil {
+					b.Fatalf("sign: %v", err)
+				}
+			}
+		})
+	}
+}