proof generation panic

Signed-off-by: Ignacio Hagopian <[email protected]>

proof_test.go

@@ -667,3 +667,42 @@ func TestStatelessDeserializeDepth2(t *testing.T) {
 		t.Fatal("differing commitment for child #0")
 	}
 }
+
+func TestProofOfAbsenceBorderCase(t *testing.T) {
+	root := New()
+
+	key1, _ := hex.DecodeString("0000000000000000000000000000000000000000000000000000000000000001")
+	key2, _ := hex.DecodeString("0001000000000000000000000000000000000000000000000000000000000001")
+
+	// Insert an arbitrary value at key 0000000000000000000000000000000000000000000000000000000000000001
+	root.Insert(oneKeyTest, fourtyKeyTest, nil)
+
+	// Generate a proof for the following keys:
+	// - key1, which is present.
+	// - key2, which isn't present.
+	// Note that all three keys will land on the same leaf value.
+	proof, _, _, _, _ := MakeVerkleMultiProof(root, keylist{key1, key2})
+
+	serialized, statediff, err := SerializeProof(proof)
+	if err != nil {
+		t.Fatalf("could not serialize proof: %v", err)
+	}
+
+	dproof, err := DeserializeProof(serialized, statediff)
+	if err != nil {
+		t.Fatalf("error deserializing proof: %v", err)
+	}
+
+	droot, err := TreeFromProof(dproof, root.Commit())
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !Equal(droot.Commit(), root.Commit()) {
+		t.Fatal("differing root commitments")
+	}
+
+	if !Equal(droot.(*InternalNode).children[0].Commit(), root.(*InternalNode).children[0].Commit()) {
+		t.Fatal("differing commitment for child #0")
+	}
+}

tree.go

@@ -1339,7 +1339,7 @@ func (n *LeafNode) GetProofItems(keys keylist) (*ProofElements, []byte, [][]byte
 			if len(esses) == 0 {
 				esses = append(esses, extStatusAbsentOther|(n.depth<<3))
 				poass = append(poass, n.stem)
-				pe.Vals = append(pe.Vals, nil)
+				pe.Vals = append(pe.Vals, nil) // jsign comment: there's the cause.
 			}
 			continue
 		}