gamma generation algorithm changed

libwhisper/Message.cpp

@@ -64,23 +64,17 @@ bool Message::openBroadcastEnvelope(Envelope const& _e, FullTopic const& _fk, by
 				break;
 			}
 
-	if (_e.data().size() < _e.topic().size() * 32)
+	if (_e.data().size() < _e.topic().size() * h256::size)
 		return false;
 
-	h256 encryptedKey = h256(bytesConstRef(&(_e.data())).cropped(32 * topicIndex, 32));
+	unsigned index = topicIndex * 2;
-	h256 key = generateGamma(topicSecret) ^ encryptedKey;
+	h256 encryptedKey = h256(bytesConstRef(&(_e.data())).cropped(h256::size * index, h256::size));
-	bytesConstRef cipherText = bytesConstRef(&(_e.data())).cropped(32 * _e.topic().size());
+	h256 salt = h256(bytesConstRef(&(_e.data())).cropped(h256::size * ++index, h256::size));
+	h256 key = generateGamma(topicSecret, salt) ^ encryptedKey;
+	bytesConstRef cipherText = bytesConstRef(&(_e.data())).cropped(h256::size * 2 * _e.topic().size());
 	return decryptSym(key, cipherText, o_b);
 }
 
-h256 Message::generateGamma(h256 const& _seed) const
-{
-	int const c_rounds = 128;
-	bytes zeroSalt;
-	bytes hashedTopic = dev::pbkdf2(_seed.hex(), zeroSalt, c_rounds);
-	return h256(hashedTopic);
-}
-
 bool Message::populate(bytes const& _data)
 {
 	if (!_data.size())
@@ -111,7 +105,7 @@ Envelope Message::seal(Secret _from, FullTopic const& _fullTopic, unsigned _ttl,
 	input[0] = 0;
 	memcpy(input.data() + 1, m_payload.data(), m_payload.size());
 
-	if (_from)		// needs a sig
+	if (_from) // needs a signature
 	{
 		input.resize(1 + m_payload.size() + sizeof(Signature));
 		input[0] |= ContainsSignature;
@@ -124,10 +118,15 @@ Envelope Message::seal(Secret _from, FullTopic const& _fullTopic, unsigned _ttl,
 		encrypt(m_to, &input, ret.m_data);
 	else
 	{
+		// this message is for broadcast (could be read by anyone who knows at least one of the topics)
 		// create the shared secret for encrypting the payload, then encrypt the shared secret with each topic
 		Secret s = Secret::random();
 		for (h256 const& t : _fullTopic)
-			ret.m_data += (generateGamma(t) ^ s).asBytes();
+		{
+			h256 salt = h256::random();
+			ret.m_data += (generateGamma(t, salt) ^ s).asBytes();
+			ret.m_data += salt.asBytes();
+		}
 
 		bytes d;
 		encryptSym(s, &input, d);

libwhisper/Message.h

@@ -127,8 +127,8 @@ public:
 
 private:
 	bool populate(bytes const& _data);
-	h256 generateGamma(h256 const& _seed) const;
 	bool openBroadcastEnvelope(Envelope const& _e, FullTopic const& _fk, bytes& o_b);
+	h256 generateGamma(h256 const& _key, h256 const& _salt) const { return sha3(_key ^ _salt); }
 
 	Public m_from;
 	Public m_to;

test/libwhisper/whisperMessage.cpp

@@ -28,7 +28,7 @@ using namespace dev::shh;
 
 struct VerbosityHolder
 {
-	VerbosityHolder() : oldLogVerbosity(g_logVerbosity) { g_logVerbosity = 10; }
+	VerbosityHolder(int _temporaryValue) : oldLogVerbosity(g_logVerbosity) { g_logVerbosity = _temporaryValue; }
 	~VerbosityHolder() { g_logVerbosity = oldLogVerbosity; }
 
 	int oldLogVerbosity;
@@ -90,14 +90,11 @@ BOOST_AUTO_TEST_SUITE(whisperMessage)
 
 BOOST_AUTO_TEST_CASE(seal)
 {
-	VerbosityHolder verbosityHolder;
+	VerbosityHolder setTemporaryLevel(10);
 	cnote << "Testing Envelope encryption...";
 
-	for (unsigned int i = 1; i < 32; ++i)
+	for (unsigned int i = 1; i < 10; ++i)
-	{
-		cnote << i;
 		sealAndOpenSingleMessage(i);
-	}
 }
 
 BOOST_AUTO_TEST_SUITE_END()