topic encryption with pbkdf2

libwhisper/Message.cpp

@@ -35,34 +35,8 @@ Message::Message(Envelope const& _e, FullTopic const& _fk, Secret const& _s)
 			if (!decrypt(_s, &(_e.data()), b))
 				return;
 			else{}
-		else
-		{
-			// public - need to get the key through combining with the topic/topicIndex we know.
-			unsigned topicIndex = 0;
-			Secret topicSecret;
-
-			// determine topicSecret/topicIndex from knowledge of the collapsed topics (which give the order) and our full-size filter topic.
-			CollapsedTopic knownTopic = collapse(_fk);
-			for (unsigned ti = 0; ti < _fk.size() && !topicSecret; ++ti)
-				for (unsigned i = 0; i < _e.topic().size(); ++i)
-					if (_e.topic()[i] == knownTopic[ti])
-					{
-						topicSecret = _fk[ti];
-						topicIndex = i;
-						break;
-					}
-
-			if (_e.data().size() < _e.topic().size() * 32)
-				return;
-
-			// get key from decrypted topic key: just xor
-			h256 tk = h256(bytesConstRef(&(_e.data())).cropped(32 * topicIndex, 32));
-			bytesConstRef cipherText = bytesConstRef(&(_e.data())).cropped(32 * _e.topic().size());
-//			cdebug << "Decrypting(" << topicIndex << "): " << topicSecret << tk << (topicSecret ^ tk) << toHex(cipherText);
-			if (!decryptSym(topicSecret ^ tk, cipherText, b))
-				return;
-//			cdebug << "Got: " << toHex(b);
-		}
+		else if (!openBroadcastEnvelope(_e, _fk, b))
+			return;
 
 		if (populate(b))
 			if (_s)
@@ -73,6 +47,40 @@ Message::Message(Envelope const& _e, FullTopic const& _fk, Secret const& _s)
 	}
 }
 
+bool Message::openBroadcastEnvelope(Envelope const& _e, FullTopic const& _fk, bytes& o_b)
+{
+	// retrieve the key using the known topic and topicIndex.
+	unsigned topicIndex = 0;
+	Secret topicSecret;
+
+	// determine topicSecret/topicIndex from knowledge of the collapsed topics (which give the order) and our full-size filter topic.
+	CollapsedTopic knownTopic = collapse(_fk);
+	for (unsigned ti = 0; ti < _fk.size() && !topicSecret; ++ti)
+		for (unsigned i = 0; i < _e.topic().size(); ++i)
+			if (_e.topic()[i] == knownTopic[ti])
+			{
+				topicSecret = _fk[ti];
+				topicIndex = i;
+				break;
+			}
+
+	if (_e.data().size() < _e.topic().size() * 32)
+		return false;
+
+	h256 encryptedKey = h256(bytesConstRef(&(_e.data())).cropped(32 * topicIndex, 32));
+	h256 key = generateGamma(topicSecret) ^ encryptedKey;
+	bytesConstRef cipherText = bytesConstRef(&(_e.data())).cropped(32 * _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())
@@ -116,23 +124,14 @@ Envelope Message::seal(Secret _from, FullTopic const& _fullTopic, unsigned _ttl,
 		encrypt(m_to, &input, ret.m_data);
 	else
 	{
-		// create the shared secret and encrypt
+		// 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 += (t ^ s).asBytes();
+		for (h256 const& t : _fullTopic)
+			ret.m_data += (generateGamma(t) ^ s).asBytes();
+
 		bytes d;
 		encryptSym(s, &input, d);
 		ret.m_data += d;
-
-		for (unsigned i = 0; i < _fullTopic.size(); ++i)
-		{
-			bytes b;
-			h256 tk = h256(bytesConstRef(&(ret.m_data)).cropped(32 * i, 32));
-			bytesConstRef cipherText = bytesConstRef(&(ret.m_data)).cropped(32 * ret.topic().size());
-			cnote << "Test decrypting(" << i << "): " << _fullTopic[i] << tk << (_fullTopic[i] ^ tk) << toHex(cipherText);
-			assert(decryptSym(_fullTopic[i] ^ tk, cipherText, b));
-			cnote << "Got: " << toHex(b);
-		}
 	}
 
 	ret.proveWork(_workToProve);

libwhisper/Message.h

@@ -127,6 +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);
 
 	Public m_from;
 	Public m_to;

test/libwhisper/whisperMessage.cpp

@@ -0,0 +1,103 @@
+/*
+This file is part of cpp-ethereum.
+
+cpp-ethereum is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+cpp-ethereum 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 General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with cpp-ethereum.  If not, see <http://www.gnu.org/licenses/>.
+*/
+/** @file whisperMessage.cpp
+* @author Vladislav Gluhovsky <vlad@ethdev.com>
+* @date May 2015
+*/
+
+#include <boost/test/unit_test.hpp>
+#include <libwhisper/Message.h>
+
+using namespace std;
+using namespace dev;
+using namespace dev::shh;
+
+struct VerbosityHolder
+{
+	VerbosityHolder() : oldLogVerbosity(g_logVerbosity) { g_logVerbosity = 10; }
+	~VerbosityHolder() { g_logVerbosity = oldLogVerbosity; }
+
+	int oldLogVerbosity;
+};
+
+FullTopic createRandomTopics(unsigned int i)
+{
+	FullTopic ret;
+	h256 t(i);
+
+	for (int j = 0; j < 8; ++j)
+	{
+		t = sha3(t);
+		ret.push_back(t);
+	}
+
+	return move(ret);
+}
+
+bytes createRandomPayload(unsigned int i)
+{
+	bytes ret;
+	srand(i);
+	int const sz = rand() % 1024;
+	for (int j = 0; j < sz; ++j)
+		ret.push_back(rand() % 256);
+
+	return move(ret);
+}
+
+void comparePayloads(Message const& m1, Message const& m2)
+{
+	bytes const& p1 = m1.payload();
+	bytes const& p2 = m2.payload();
+	BOOST_REQUIRE_EQUAL(p1.size(), p2.size());
+
+	for (size_t i = 0; i < p1.size(); ++i)
+		BOOST_REQUIRE_EQUAL(p1[i], p2[i]);
+}
+
+void sealAndOpenSingleMessage(unsigned int i)
+{
+	Secret zero;
+	FullTopic topics = createRandomTopics(i);
+	bytes const payload = createRandomPayload(i);
+	Message m1(payload);
+	Envelope e = m1.seal(zero, topics, 1, 1);
+
+	for (auto const& t: topics)
+	{
+		FullTopic singleTopic;
+		singleTopic.push_back(t);
+		Message m2(e, singleTopic, zero);
+		comparePayloads(m1, m2);
+	}
+}
+
+BOOST_AUTO_TEST_SUITE(whisperMessage)
+
+BOOST_AUTO_TEST_CASE(seal)
+{
+	VerbosityHolder verbosityHolder;
+	cnote << "Testing Envelope encryption...";
+
+	for (unsigned int i = 1; i < 32; ++i)
+	{
+		cnote << i;
+		sealAndOpenSingleMessage(i);
+	}
+}
+
+BOOST_AUTO_TEST_SUITE_END()