tunnels through ECIES routers

libi2pd/I2NPProtocol.h

@@ -81,6 +81,25 @@ namespace i2p
 	const size_t BUILD_RESPONSE_RECORD_PADDING_SIZE = 495;
 	const size_t BUILD_RESPONSE_RECORD_RET_OFFSET = BUILD_RESPONSE_RECORD_PADDING_OFFSET + BUILD_RESPONSE_RECORD_PADDING_SIZE;
 
+	// ECIES BuildRequestRecordClearText
+	const size_t ECIES_BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET = 0;
+	const size_t ECIES_BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET = ECIES_BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET + 4;
+	const size_t ECIES_BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET = ECIES_BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET + 4;
+	const size_t ECIES_BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET = ECIES_BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET + 32;
+	const size_t ECIES_BUILD_REQUEST_RECORD_IV_KEY_OFFSET = ECIES_BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET + 32;
+	const size_t ECIES_BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET = ECIES_BUILD_REQUEST_RECORD_IV_KEY_OFFSET + 32;
+	const size_t ECIES_BUILD_REQUEST_RECORD_REPLY_IV_OFFSET = ECIES_BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET + 32;
+	const size_t ECIES_BUILD_REQUEST_RECORD_FLAG_OFFSET = ECIES_BUILD_REQUEST_RECORD_REPLY_IV_OFFSET + 16;
+	const size_t ECIES_BUILD_REQUEST_RECORD_MORE_FLAGS_OFFSET = ECIES_BUILD_REQUEST_RECORD_FLAG_OFFSET + 1;
+	const size_t ECIES_BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET = ECIES_BUILD_REQUEST_RECORD_MORE_FLAGS_OFFSET + 3;
+	const size_t ECIES_BUILD_REQUEST_RECORD_REQUEST_EXPIRATION_OFFSET = ECIES_BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET + 4;
+	const size_t ECIES_BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET = ECIES_BUILD_REQUEST_RECORD_REQUEST_EXPIRATION_OFFSET + 4;
+	const size_t ECIES_BUILD_REQUEST_RECORD_PADDING_OFFSET = ECIES_BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET + 4;
+	const size_t ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE = 464;
+
+	// ECIES BuildResponseRecord
+	const size_t ECIES_BUILD_RESPONSE_RECORD_RET_OFFSET = 511;
+	
 	enum I2NPMessageType
 	{
 		eI2NPDummyMsg = 0,

libi2pd/Timestamp.cpp

@@ -35,15 +35,21 @@ namespace util
 			std::chrono::system_clock::now().time_since_epoch()).count ();
 	}
 
-	static uint32_t GetLocalHoursSinceEpoch ()
+	static uint64_t GetLocalSecondsSinceEpoch ()
 	{
-		return std::chrono::duration_cast<std::chrono::hours>(
+		return std::chrono::duration_cast<std::chrono::seconds>(
 			std::chrono::system_clock::now().time_since_epoch()).count ();
 	}
 
-	static uint64_t GetLocalSecondsSinceEpoch ()
+	static uint32_t GetLocalMinutesSinceEpoch ()
 	{
-		return std::chrono::duration_cast<std::chrono::seconds>(
+		return std::chrono::duration_cast<std::chrono::minutes>(
+			std::chrono::system_clock::now().time_since_epoch()).count ();
+	}
+	
+	static uint32_t GetLocalHoursSinceEpoch ()
+	{
+		return std::chrono::duration_cast<std::chrono::hours>(
 			std::chrono::system_clock::now().time_since_epoch()).count ();
 	}
 
@@ -178,14 +184,19 @@ namespace util
 		return GetLocalMillisecondsSinceEpoch () + g_TimeOffset*1000;
 	}
 
-	uint32_t GetHoursSinceEpoch ()
+	uint64_t GetSecondsSinceEpoch ()
 	{
-		return GetLocalHoursSinceEpoch () + g_TimeOffset/3600;
+		return GetLocalSecondsSinceEpoch () + g_TimeOffset;
 	}	
 	
-	uint64_t GetSecondsSinceEpoch ()
+	uint32_t GetMinutesSinceEpoch ()
 	{
-		return GetLocalSecondsSinceEpoch () + g_TimeOffset;
+		return GetLocalMinutesSinceEpoch () + g_TimeOffset/60;
+	}
+	
+	uint32_t GetHoursSinceEpoch ()
+	{
+		return GetLocalHoursSinceEpoch () + g_TimeOffset/3600;
 	}
 
 	void GetCurrentDate (char * date)

libi2pd/Timestamp.h

@@ -20,8 +20,9 @@ namespace i2p
 namespace util
 {
 	uint64_t GetMillisecondsSinceEpoch ();
-	uint32_t GetHoursSinceEpoch ();
 	uint64_t GetSecondsSinceEpoch ();
+	uint32_t GetMinutesSinceEpoch ();
+	uint32_t GetHoursSinceEpoch ();
 
 	void GetCurrentDate (char * date); // returns date as YYYYMMDD string, 9 bytes
 	void GetDateString (uint64_t timestamp, char * date); // timestap is seconds since epoch, returns date as YYYYMMDD string, 9 bytes

libi2pd/Tunnel.cpp

@@ -111,7 +111,7 @@ namespace tunnel
 		while (hop)
 		{
 			decryption.SetKey (hop->replyKey);
-			// decrypt records before and including current hop
+			// decrypt records before and current hop 
 			TunnelHopConfig * hop1 = hop;
 			while (hop1)
 			{
@@ -119,8 +119,22 @@ namespace tunnel
 				if (idx >= 0 && idx < msg[0])
 				{
 					uint8_t * record = msg + 1 + idx*TUNNEL_BUILD_RECORD_SIZE;
-					decryption.SetIV (hop->replyIV);
-					decryption.Decrypt(record, TUNNEL_BUILD_RECORD_SIZE, record);
+					if (hop1 == hop && hop1->IsECIES ())
+					{
+						uint8_t nonce[12];
+						memset (nonce, 0, 12);
+						if (!i2p::crypto::AEADChaCha20Poly1305 (record, TUNNEL_BUILD_RECORD_SIZE - 16, 
+							hop->h, 32, hop->ck, nonce, record, TUNNEL_BUILD_RECORD_SIZE - 16, false)) // decrypt
+						{
+							LogPrint (eLogWarning, "Tunnel: Response AEAD decryption failed");
+							return false;
+						}	
+					}
+					else
+					{	
+						decryption.SetIV (hop->replyIV);
+						decryption.Decrypt(record, TUNNEL_BUILD_RECORD_SIZE, record);
+					}	
 				}
 				else
 					LogPrint (eLogWarning, "Tunnel: hop index ", idx, " is out of range");
@@ -134,7 +148,7 @@ namespace tunnel
 		while (hop)
 		{
 			const uint8_t * record = msg + 1 + hop->recordIndex*TUNNEL_BUILD_RECORD_SIZE;
-			uint8_t ret = record[BUILD_RESPONSE_RECORD_RET_OFFSET];
+			uint8_t ret = record[hop->IsECIES () ? ECIES_BUILD_RESPONSE_RECORD_RET_OFFSET : BUILD_RESPONSE_RECORD_RET_OFFSET];
 			LogPrint (eLogDebug, "Tunnel: Build response ret code=", (int)ret);
 			auto profile = i2p::data::netdb.FindRouterProfile (hop->ident->GetIdentHash ());
 			if (profile)

libi2pd/TunnelConfig.cpp

@@ -9,6 +9,9 @@
 
 #include <memory>
 #include <openssl/rand.h>
+#include <openssl/sha.h>
+#include "Crypto.h"
+#include "Log.h"
 #include "Transports.h"
 #include "Timestamp.h"
 #include "I2PEndian.h"
@@ -76,39 +79,86 @@ namespace tunnel
 		}
 	}
 	
-	void TunnelHopConfig::CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID, BN_CTX * ctx) const
+	void TunnelHopConfig::CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID, BN_CTX * ctx)
 	{
-		uint8_t clearText[BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE];
-		htobe32buf (clearText + BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID);
-		memcpy (clearText + BUILD_REQUEST_RECORD_OUR_IDENT_OFFSET, ident->GetIdentHash (), 32);
-		htobe32buf (clearText + BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET, nextTunnelID);
-		memcpy (clearText + BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET, nextIdent, 32);
-		memcpy (clearText + BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET, layerKey, 32);
-		memcpy (clearText + BUILD_REQUEST_RECORD_IV_KEY_OFFSET, ivKey, 32);
-		memcpy (clearText + BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET, replyKey, 32);
-		memcpy (clearText + BUILD_REQUEST_RECORD_REPLY_IV_OFFSET, replyIV, 16);
 		uint8_t flag = 0;
 		if (isGateway) flag |= 0x80;
 		if (isEndpoint) flag |= 0x40;
-		clearText[BUILD_REQUEST_RECORD_FLAG_OFFSET] = flag;
-		htobe32buf (clearText + BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET, i2p::util::GetHoursSinceEpoch ());
-		htobe32buf (clearText + BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET, replyMsgID);
-		RAND_bytes (clearText + BUILD_REQUEST_RECORD_PADDING_OFFSET, BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE - BUILD_REQUEST_RECORD_PADDING_OFFSET);
 		auto encryptor = ident->CreateEncryptor (nullptr);
-		if (encryptor)
+		if (IsECIES ())
 		{
-			if (ident->GetCryptoKeyType () == i2p::data::CRYPTO_KEY_TYPE_ECIES_X25519_AEAD_RATCHET)
+			uint8_t clearText[ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE];
+			htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID);
+			htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET, nextTunnelID);
+			memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET, nextIdent, 32);
+			memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET, layerKey, 32);
+			memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_IV_KEY_OFFSET, ivKey, 32);
+			memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET, replyKey, 32);
+			memcpy (clearText + ECIES_BUILD_REQUEST_RECORD_REPLY_IV_OFFSET, replyIV, 16);
+			clearText[ECIES_BUILD_REQUEST_RECORD_FLAG_OFFSET] = flag;
+			memset (clearText + ECIES_BUILD_REQUEST_RECORD_MORE_FLAGS_OFFSET, 0, 3); // set to 0 for compatibility
+			htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET, i2p::util::GetMinutesSinceEpoch ());
+			htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_REQUEST_EXPIRATION_OFFSET, i2p::util::GetSecondsSinceEpoch () + 600); // 10 minutes
+			htobe32buf (clearText + ECIES_BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET, replyMsgID);
+			memset (clearText + ECIES_BUILD_REQUEST_RECORD_PADDING_OFFSET, 0, ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE - ECIES_BUILD_REQUEST_RECORD_PADDING_OFFSET);
+			if (encryptor)
 				EncryptECIES (encryptor, clearText, record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET, ctx);
-			else	
+		}
+		else
+		{	
+			uint8_t clearText[BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE];
+			htobe32buf (clearText + BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID);
+			memcpy (clearText + BUILD_REQUEST_RECORD_OUR_IDENT_OFFSET, ident->GetIdentHash (), 32);
+			htobe32buf (clearText + BUILD_REQUEST_RECORD_NEXT_TUNNEL_OFFSET, nextTunnelID);
+			memcpy (clearText + BUILD_REQUEST_RECORD_NEXT_IDENT_OFFSET, nextIdent, 32);
+			memcpy (clearText + BUILD_REQUEST_RECORD_LAYER_KEY_OFFSET, layerKey, 32);
+			memcpy (clearText + BUILD_REQUEST_RECORD_IV_KEY_OFFSET, ivKey, 32);
+			memcpy (clearText + BUILD_REQUEST_RECORD_REPLY_KEY_OFFSET, replyKey, 32);
+			memcpy (clearText + BUILD_REQUEST_RECORD_REPLY_IV_OFFSET, replyIV, 16);
+			clearText[BUILD_REQUEST_RECORD_FLAG_OFFSET] = flag;
+			htobe32buf (clearText + BUILD_REQUEST_RECORD_REQUEST_TIME_OFFSET, i2p::util::GetHoursSinceEpoch ());
+			htobe32buf (clearText + BUILD_REQUEST_RECORD_SEND_MSG_ID_OFFSET, replyMsgID);
+			RAND_bytes (clearText + BUILD_REQUEST_RECORD_PADDING_OFFSET, BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE - BUILD_REQUEST_RECORD_PADDING_OFFSET);
+			if (encryptor)
 				encryptor->Encrypt (clearText, record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET, ctx, false);
 		}	
 		memcpy (record + BUILD_REQUEST_RECORD_TO_PEER_OFFSET, (const uint8_t *)ident->GetIdentHash (), 16);
 	}
 
 	void TunnelHopConfig::EncryptECIES (std::shared_ptr<i2p::crypto::CryptoKeyEncryptor>& encryptor, 
-			const uint8_t * clearText, uint8_t * encrypted, BN_CTX * ctx) const
+			const uint8_t * plainText, uint8_t * encrypted, BN_CTX * ctx)
+	{
+		static const char protocolName[] = "Noise_N_25519_ChaChaPoly_SHA256"; // 31 chars
+		memcpy (ck, protocolName, 32);	// ck = h = protocol_name || 0
+		SHA256 (ck, 32, h); // h = SHA256(h);
+		uint8_t hepk[32];
+		encryptor->Encrypt (nullptr, hepk, nullptr, false); 
+		MixHash (hepk, 32);
+		auto ephemeralKeys = i2p::transport::transports.GetNextX25519KeysPair ();
+		memcpy (encrypted, ephemeralKeys->GetPublicKey (), 32); encrypted += 32;
+		uint8_t sharedSecret[32];
+		ephemeralKeys->Agree (hepk, sharedSecret); // x25519(sesk, hepk)
+		uint8_t keydata[64];
+		i2p::crypto::HKDF (ck, sharedSecret, 32, "", keydata); 
+		memcpy (ck, keydata, 32);
+		uint8_t nonce[12];
+		memset (nonce, 0, 12);
+		if (!i2p::crypto::AEADChaCha20Poly1305 (plainText, ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE, h, 32, 
+			keydata + 32, nonce, encrypted, ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE + 16, true)) // encrypt
+		{	
+			LogPrint (eLogWarning, "Tunnel: Plaintext AEAD encryption failed");
+			return;
+		}	
+		MixHash (encrypted, ECIES_BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE + 16); // h = SHA256(h || ciphertext)
+	}	
+
+	void TunnelHopConfig::MixHash (const uint8_t * buf, size_t len)
 	{
-		memset (encrypted, 0, 512); // TODO: implement
+		SHA256_CTX ctx;
+		SHA256_Init (&ctx);
+		SHA256_Update (&ctx, h, 32);
+		SHA256_Update (&ctx, buf, len);
+		SHA256_Final (h, &ctx);
 	}
 }
 }

libi2pd/TunnelConfig.h

@@ -30,6 +30,7 @@ namespace tunnel
 
 		TunnelHopConfig * next, * prev;
 		int recordIndex; // record # in tunnel build message
+		uint8_t ck[32], h[32]; // for ECIES
 	
 		TunnelHopConfig (std::shared_ptr<const i2p::data::IdentityEx> r);
 	
@@ -38,9 +39,11 @@ namespace tunnel
 		void SetNext (TunnelHopConfig * n);
 		void SetPrev (TunnelHopConfig * p);		
 
-		void CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID, BN_CTX * ctx) const;
+		bool IsECIES () const { return ident->GetCryptoKeyType () == i2p::data::CRYPTO_KEY_TYPE_ECIES_X25519_AEAD_RATCHET; };
+		void CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID, BN_CTX * ctx);
 		void EncryptECIES (std::shared_ptr<i2p::crypto::CryptoKeyEncryptor>& encryptor, 
-			const uint8_t * clearText, uint8_t * encrypted, BN_CTX * ctx) const;
+			const uint8_t * clearText, uint8_t * encrypted, BN_CTX * ctx);
+		void MixHash (const uint8_t * buf, size_t len);
 	};
 
 	class TunnelConfig