diff --git a/SSUData.cpp b/SSUData.cpp
index a1b8163b..db71edb7 100644
--- a/SSUData.cpp
+++ b/SSUData.cpp
@@ -19,8 +19,27 @@ namespace ssu
 				DeleteI2NPMessage (it.second->msg);
 				delete it.second;
 			}	
+		for (auto it: m_SentMessages)
+		{
+			for (auto f: it.second)
+			delete[] f;
+		}	
 	}
 
+	void SSUData::ProcessSentMessageAck (uint32_t msgID)
+	{
+		auto it = m_SentMessages.find (msgID);
+		if (it != m_SentMessages.end ())
+		{
+			// delete all ack-ed message's fragments
+			for (auto f: it->second)
+				delete[] f;
+			m_SentMessages.erase (it);	
+		}
+		else
+			LogPrint ("SSU ack received for unknown message ", msgID);
+	}		
+
 	void SSUData::ProcessMessage (uint8_t * buf, size_t len)
 	{
 		//uint8_t * start = buf;
@@ -32,7 +51,8 @@ namespace ssu
 			// explicit ACKs
 			uint8_t numAcks =*buf;
 			buf++;
-			// TODO: process ACKs
+			for (int i = 0; i < numAcks; i++)
+				ProcessSentMessageAck (be32toh (((uint32_t *)buf)[i]));
 			buf += numAcks*4;
 		}
 		if (flag & DATA_FLAG_ACK_BITFIELDS_INCLUDED)
@@ -42,8 +62,9 @@ namespace ssu
 			buf++;
 			for (int i = 0; i < numBitfields; i++)
 			{
+				ProcessSentMessageAck (be32toh (*(uint32_t *)buf)); // TODO: should be replaced to fragments
 				buf += 4; // msgID
-				// TODO: process ACH bitfields
+				// TODO: process individual Ack bitfields
 				while (*buf & 0x80) // not last
 					buf++;
 				buf++; // last byte
@@ -137,7 +158,9 @@ namespace ssu
 
 	void SSUData::Send (i2p::I2NPMessage * msg)
 	{
-		uint32_t msgID = htobe32 (msg->ToSSU ());
+		uint32_t msgID = msg->ToSSU ();
+		auto fragments = m_SentMessages[msgID];
+		msgID = htobe32 (msgID);	
 		size_t payloadSize = SSU_MTU - sizeof (SSUHeader) - 9; // 9  =  flag + #frg(1) + messageID(4) + frag info (3) 
 		size_t len = msg->GetLength ();
 		uint8_t * msgBuf = msg->GetSSUHeader ();
@@ -145,7 +168,9 @@ namespace ssu
 		uint32_t fragmentNum = 0;
 		while (len > 0)
 		{	
-			uint8_t buf[SSU_MTU + 18], * payload = buf + sizeof (SSUHeader);
+			uint8_t * buf = new uint8_t[SSU_MTU + 18];
+			fragments.push_back (buf);
+			uint8_t	* payload = buf + sizeof (SSUHeader);
 			*payload = DATA_FLAG_WANT_REPLY; // for compatibility
 			payload++;
 			*payload = 1; // always 1 message fragment per message
diff --git a/SSUData.h b/SSUData.h
index 71273dc2..4829aa56 100644
--- a/SSUData.h
+++ b/SSUData.h
@@ -3,6 +3,7 @@
 
 #include <inttypes.h>
 #include <map>
+#include <vector>
 #include "I2NPProtocol.h"
 
 namespace i2p
@@ -32,6 +33,7 @@ namespace ssu
 		private:
 
 			void SendMsgAck (uint32_t msgID);
+			void ProcessSentMessageAck (uint32_t msgID);
 
 		private:
 
@@ -45,6 +47,7 @@ namespace ssu
 
 			SSUSession& m_Session;
 			std::map<uint32_t, IncompleteMessage *> m_IncomleteMessages;
+			std::map<uint32_t, std::vector<uint8_t *> > m_SentMessages; // msgID -> fragments	
 	};	
 }
 }