fix: redundant proof-of-absence stems (ethereum#93)

go.mod

@@ -26,7 +26,7 @@ require (
 	github.com/fatih/color v1.7.0
 	github.com/fjl/memsize v0.0.0-20190710130421-bcb5799ab5e5
 	github.com/gballet/go-libpcsclite v0.0.0-20190607065134-2772fd86a8ff
-	github.com/gballet/go-verkle v0.0.0-20220330063001-d9fddb499b7a
+	github.com/gballet/go-verkle v0.0.0-20220401072859-0ae88725b839
 	github.com/go-ole/go-ole v1.2.1 // indirect
 	github.com/go-stack/stack v1.8.0
 	github.com/golang/protobuf v1.4.3

go.sum

@@ -181,6 +181,8 @@ github.com/gballet/go-verkle v0.0.0-20220309192943-d9f613553c79 h1:IGryvoVakS5AN
 github.com/gballet/go-verkle v0.0.0-20220309192943-d9f613553c79/go.mod h1:S2TbrZxLyGqCqwtl2IA09xxun6oretK6byC1lHY+sAk=
 github.com/gballet/go-verkle v0.0.0-20220330063001-d9fddb499b7a h1:WDnnkoIpO6lqoUydcAzsrYnXOaZyZCFBz3IIRZy5fZ0=
 github.com/gballet/go-verkle v0.0.0-20220330063001-d9fddb499b7a/go.mod h1:S2TbrZxLyGqCqwtl2IA09xxun6oretK6byC1lHY+sAk=
+github.com/gballet/go-verkle v0.0.0-20220401072859-0ae88725b839 h1:Dmwdz0Db5n3PwCu+xvrnyIohV7PMfsfaFFuUDULMJyU=
+github.com/gballet/go-verkle v0.0.0-20220401072859-0ae88725b839/go.mod h1:S2TbrZxLyGqCqwtl2IA09xxun6oretK6byC1lHY+sAk=
 github.com/getkin/kin-openapi v0.53.0/go.mod h1:7Yn5whZr5kJi6t+kShccXS8ae1APpYTW6yheSwk8Yi4=
 github.com/getkin/kin-openapi v0.61.0/go.mod h1:7Yn5whZr5kJi6t+kShccXS8ae1APpYTW6yheSwk8Yi4=
 github.com/ghodss/yaml v1.0.0/go.mod h1:4dBDuWmgqj2HViK6kFavaiC9ZROes6MMH2rRYeMEF04=

trie/verkle_test.go

@@ -254,3 +254,50 @@ func TestChunkifyCodeFuzz(t *testing.T) {
 	}
 	t.Logf("code=%x, chunks=%x\n", code, chunks)
 }
+
+// Cover the case in which a stem is both used for a proof of absence, and for a proof of presence.
+func TestReproduceCondrieuPoAStemConflictWithAnotherStem(t *testing.T) {
+	presentKeys := [][]byte{
+		common.Hex2Bytes("6766d007d8fd90ea45b2ac9027ff04fa57e49527f11010a12a73f58ffa580800"),
+	}
+
+	absentKeys := [][]byte{
+		common.Hex2Bytes("6766d007d8fd90ea45b2ac9027ff04fa57e49527f11010a12a73008ffa580800"),
+		// the key differs from the key present...                            ^^ here
+	}
+
+	values := [][]byte{
+		common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000000"),
+	}
+
+	root := verkle.New()
+	kv := make(map[string][]byte)
+
+	for i, key := range presentKeys {
+		root.Insert(key, values[i], nil)
+		kv[string(key)] = values[i]
+	}
+
+	proof, Cs, zis, yis := verkle.MakeVerkleMultiProof(root, append(presentKeys, absentKeys...), kv)
+	cfg, _ := verkle.GetConfig()
+	if !verkle.VerifyVerkleProof(proof, Cs, zis, yis, cfg) {
+		t.Fatal("could not verify proof")
+	}
+
+	t.Log("commitments returned by proof:")
+	for i, c := range Cs {
+		t.Logf("%d %x", i, c.Bytes())
+	}
+
+	p, _, err := verkle.SerializeProof(proof)
+	if err != nil {
+		t.Fatal(err)
+	}
+	t.Logf("serialized: %x", p)
+	t.Logf("tree: %s\n%x\n", verkle.ToDot(root), root.ComputeCommitment().Bytes())
+
+	t.Logf("%d", len(proof.ExtStatus))
+	if len(proof.PoaStems) != 0 {
+		t.Fatal("a proof-of-absence stem was declared, when there was no need")
+	}
+}