whisper: individual filters can only have one type of key

It has been decided not to allow filters to be both for
symmetric and asymmetric keys, because that's already
what the API enforces.

whisper/whisperv6/envelope.go

@@ -208,17 +208,18 @@ func (e *Envelope) OpenSymmetric(key []byte) (msg *ReceivedMessage, err error) {
 
 // Open tries to decrypt an envelope, and populates the message fields in case of success.
 func (e *Envelope) Open(watcher *Filter) (msg *ReceivedMessage) {
-	// if the filter has some asymmetric key provided, it will
-	// attempt to open it asymmetrically. If this fails, then
-	// attempt to open it symmetrically.
+	// The API interface forbids filters doing both symmetric and
+	// asymmetric encryption.
+	if watcher.expectsAsymmetricEncryption() && watcher.expectsSymmetricEncryption() {
+		return nil
+	}
+
 	if watcher.expectsAsymmetricEncryption() {
 		msg, _ = e.OpenAsymmetric(watcher.KeyAsym)
 		if msg != nil {
 			msg.Dst = &watcher.KeyAsym.PublicKey
 		}
-	}
-
-	if msg == nil && watcher.expectsSymmetricEncryption() {
+	} else if watcher.expectsSymmetricEncryption() {
 		msg, _ = e.OpenSymmetric(watcher.KeySym)
 		if msg != nil {
 			msg.SymKeyHash = crypto.Keccak256Hash(watcher.KeySym)

whisper/whisperv6/envelope_test.go

@@ -0,0 +1,64 @@
+// Copyright 2017 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Contains the tests associated with the Whisper protocol Envelope object.
+
+package whisperv6
+
+import (
+	mrand "math/rand"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+func TestEnvelopeOpenAcceptsOnlyOneKeyTypeInFilter(t *testing.T) {
+	symKey := make([]byte, aesKeyLength)
+	mrand.Read(symKey)
+
+	asymKey, err := crypto.GenerateKey()
+	if err != nil {
+		t.Fatalf("failed GenerateKey with seed %d: %s.", seed, err)
+	}
+
+	params := MessageParams{
+		PoW:      0.01,
+		WorkTime: 1,
+		TTL:      uint32(mrand.Intn(1024)),
+		Payload:  make([]byte, 50),
+		KeySym:   symKey,
+		Dst:      nil,
+	}
+
+	mrand.Read(params.Payload)
+
+	msg, err := NewSentMessage(&params)
+	if err != nil {
+		t.Fatalf("failed to create new message with seed %d: %s.", seed, err)
+	}
+
+	e, err := msg.Wrap(&params)
+	if err != nil {
+		t.Fatalf("Failed to Wrap the message in an envelope with seed %d: %s", seed, err)
+	}
+
+	f := Filter{KeySym: symKey, KeyAsym: asymKey}
+
+	decrypted := e.Open(&f)
+	if decrypted != nil {
+		t.Fatalf("Managed to decrypt a message with an invalid filter, seed %d", seed)
+	}
+}

whisper/whisperv6/filter.go

@@ -53,6 +53,10 @@ func NewFilters(w *Whisper) *Filters {
 }
 
 func (fs *Filters) Install(watcher *Filter) (string, error) {
+	if watcher.KeySym != nil && watcher.KeyAsym != nil {
+		return "", fmt.Errorf("filters must choose between symmetric and asymmetric keys")
+	}
+
 	if watcher.Messages == nil {
 		watcher.Messages = make(map[common.Hash]*ReceivedMessage)
 	}

whisper/whisperv6/filter_test.go

@@ -229,6 +229,36 @@ func TestInstallIdenticalFilters(t *testing.T) {
 	}
 }
 
+func TestInstallFilterWithSymAndAsymKeys(t *testing.T) {
+	InitSingleTest()
+
+	w := New(&Config{})
+	filters := NewFilters(w)
+	filter1, _ := generateFilter(t, true)
+
+	asymKey, err := crypto.GenerateKey()
+	if err != nil {
+		t.Fatalf("Unable to create asymetric keys", err)
+	}
+
+	// Copy the first filter since some of its fields
+	// are randomly gnerated.
+	filter := &Filter{
+		KeySym:   filter1.KeySym,
+		KeyAsym:  asymKey,
+		Topics:   filter1.Topics,
+		PoW:      filter1.PoW,
+		AllowP2P: filter1.AllowP2P,
+		Messages: make(map[common.Hash]*ReceivedMessage),
+	}
+
+	_, err = filters.Install(filter)
+
+	if err == nil {
+		t.Fatalf("Error detecting that a filter had both an asymmetric and symmetric key, with seed %d", seed)
+	}
+}
+
 func TestComparePubKey(t *testing.T) {
 	InitSingleTest()
 

whisper/whisperv6/message_test.go

@@ -240,7 +240,12 @@ func singleEnvelopeOpenTest(t *testing.T, symmetric bool) {
 		t.Fatalf("failed Wrap with seed %d: %s.", seed, err)
 	}
 
-	f := Filter{KeyAsym: key, KeySym: params.KeySym}
+	var f Filter
+	if symmetric {
+		f = Filter{KeySym: params.KeySym}
+	} else {
+		f = Filter{KeyAsym: key}
+	}
 	decrypted := env.Open(&f)
 	if decrypted == nil {
 		t.Fatalf("failed to open with seed %d.", seed)