moved compute cwbits to a separate function

preprocessing/dpfgen.h

@@ -272,14 +272,46 @@ void write_evalfull_outs_into_a_file(bool party, size_t i, size_t db_nitems,  in
 	}
 }
 
-void compute_CW(tcp::socket& sout, tcp::socket& sin, __m128i L, __m128i R, uint8_t bit, __m128i & CW)
+
+struct cw_construction
 {
+  __m128i rand_b, gamma_b;
+  uint8_t bit_b;
+};
+
+struct BlindsCW
+{
+	__m128i blinded_message;
+	uint8_t blinded_bit;
+};
 
-	struct cw_construction
-	{
-	  __m128i rand_b, gamma_b;
-	  uint8_t bit_b;
-	};
+
+void compute_CW_bits(tcp::socket& sout,   __m128i L, __m128i R, uint8_t bit, uint8_t &cwt_L, uint8_t &cwt_R)
+{
+		uint8_t advice_L = get_lsb(L) ^ bit;
+		uint8_t advice_R = get_lsb(R) ^ bit;
+
+			
+		
+		uint8_t advice[2];
+		uint8_t cwts[2];	
+
+		advice[0] = advice_L;
+		advice[1] = advice_R;
+			
+		boost::asio::write(sout, boost::asio::buffer(&advice, sizeof(advice)));
+		boost::asio::read(sout, boost::asio::buffer(&cwts, sizeof(cwts)));
+			
+		cwt_L = cwts[0];
+		cwt_R = cwts[1];
+
+		cwt_L = cwt_L ^ advice_L ^ 1;
+		cwt_R = cwt_R ^ advice_R;	
+
+}
+
+void compute_CW(tcp::socket& sout, tcp::socket& sin, __m128i L, __m128i R, uint8_t bit, __m128i & CW)
+{
 
 
 	cw_construction computecw;
@@ -290,8 +322,6 @@ void compute_CW(tcp::socket& sout, tcp::socket& sin, __m128i L, __m128i R, uint8
 	__m128i gamma_b = computecw.gamma_b;
 	uint8_t bit_b   = computecw.bit_b;
 	
-
-
 	#ifdef DEBUG 
 		__m128i rand_b2, gamma_b2;
 		uint8_t bit_b2;
@@ -312,22 +342,11 @@ void compute_CW(tcp::socket& sout, tcp::socket& sin, __m128i L, __m128i R, uint8
 	__m128i blinded_L = L ^ R ^ rand_b;
 	__m128i blinded_L_read; 
 
-
-	struct BlindsCW
-	{
-		__m128i blinded_message;
-		uint8_t blinded_bit;
-	};
-
 	BlindsCW blinds_sent, blinds_recv;
-
 	blinds_sent.blinded_bit = blinded_bit;
 	blinds_sent.blinded_message = blinded_L;
-
- 
- 
- 	boost::asio::write(sout, boost::asio::buffer(&blinds_sent, sizeof(blinds_sent)));
-	boost::asio::read(sout, boost::asio::buffer(&blinds_recv, sizeof(blinds_recv)));
+ 	boost::asio::write(sout, boost::asio::buffer(&blinds_sent, sizeof(BlindsCW)));
+	boost::asio::read(sout, boost::asio::buffer(&blinds_recv, sizeof(BlindsCW)));
 	
 	blinded_bit_read = blinds_recv.blinded_bit;
 	blinded_L_read   =  blinds_recv.blinded_message;
@@ -452,7 +471,7 @@ inline void create_dpfs(  size_t db_nitems,
 
  
 	dpfP2 dpf_instance;
-	dpf_instance.root           = root;
+	dpf_instance.root = root;
 	for (size_t layer = 0; layer < depth; ++layer)
 	{
 			#ifdef VERBOSE	
@@ -486,29 +505,14 @@ inline void create_dpfs(  size_t db_nitems,
 				}
 			}
 
+			// Computes the correction word using OSWAP
 			compute_CW(socketsPb[socket_no], socketsP2[socket_no], L,  R, target_share[layer], CW[layer]);
 
-			uint8_t advice_L = get_lsb(L) ^ target_share[layer];
-			uint8_t advice_R = get_lsb(R) ^ target_share[layer];
-
 			uint8_t cwt_L, cwt_R;
-		
-			uint8_t advice[2];
-			uint8_t cwts[2];	
-
-			advice[0] = advice_L;
-			advice[1] = advice_R;
-			
-			boost::asio::write(socketsPb[socket_no+1], boost::asio::buffer(&advice, sizeof(advice)));
-			boost::asio::read(socketsPb[socket_no+1], boost::asio::buffer(&cwts, sizeof(cwts)));
+			// Computes the correction word bits
+			compute_CW_bits(socketsPb[socket_no+1], L,  R, target_share[layer], cwt_L,  cwt_R);
 			
-			cwt_L = cwts[0];
-			cwt_R = cwts[1];
-
-			cwt_L = cwt_L ^ advice_L ^ 1;
-			cwt_R = cwt_R ^ advice_R;	 	
-			
-			 #ifdef DEBUG
+			#ifdef DEBUG
 				if(ind == 0) 
 				{ 
 					std::cout << "CW reconstruction  = " << CW[layer][0] << " " << CW[layer][1] << std::endl;
@@ -522,8 +526,6 @@ inline void create_dpfs(  size_t db_nitems,
 			dpf_instance.cwt_L[layer]   =  cwt_L;
 			dpf_instance.cwt_R[layer]   =  cwt_R;
 			
-
-
 			for(size_t j = 0; j < nodes_in_prev_layer; ++j)
 			{	
 				t[curlayer][2*j] 	 = get_lsb(s[curlayer][2*j]) ^ (cwt_L & t[1-curlayer][j]);
@@ -533,26 +535,28 @@ inline void create_dpfs(  size_t db_nitems,
 			}
 	}
  
-		boost::asio::write(socketsP2[socket_no+1], boost::asio::buffer(&dpf_instance, sizeof(dpfP2)));
+	boost::asio::write(socketsP2[socket_no+1], boost::asio::buffer(&dpf_instance, sizeof(dpfP2)));
 	 
 	__m128i Gamma  =  _mm_setzero_si128();
 	 
 	for (size_t i = 0; i < to + 1; ++i)
 	{
-	  Gamma[0] += output[i][0];
+	  Gamma[0] += output[i][0]; // the correction word for duoram update
 	  Gamma[1] += output[i][1]; // the correction word for share conversion
 	}
 		
 	if(party) 
 	{
-	  Gamma[0] = -Gamma[0];
+	  Gamma[0] = -Gamma[0];  // the correction word for duoram update
 	  Gamma[1] = -Gamma[1];  // the correction word for share conversion
 	}
 	
-	// boost::asio::write(socketsPb[socket_no + 3], boost::asio::buffer(&Gamma, sizeof(Gamma)));
- 	// boost::asio::read(socketsPb[socket_no + 3], boost::asio::buffer(&final_correction_word, sizeof(final_correction_word)));
+	#ifdef DEBUG
+		boost::asio::write(socketsPb[socket_no + 3], boost::asio::buffer(&Gamma, sizeof(Gamma)));
+ 		boost::asio::read(socketsPb[socket_no + 3], boost::asio::buffer(&final_correction_word, sizeof(final_correction_word)));
+	#endif
 
- 	final_correction_word = Gamma; // final_correction_word + Gamma;
+ 	final_correction_word = Gamma;  
 
 } // dpf::__evalinterval
 
@@ -606,6 +610,7 @@ inline void evaluate_dpfs( size_t db_nitems,  dpfP2 dpfinstance,  const AES_KEY&
 			std::cout << "t[curlayer][0] " << (int) t[curlayer][0] << std::endl;
 		}
 	#endif
+
 	for (size_t layer = 0; layer < depth; ++layer)
 	{
 			#ifdef VERBOSE	
@@ -618,13 +623,10 @@ inline void evaluate_dpfs( size_t db_nitems,  dpfP2 dpfinstance,  const AES_KEY&
 			auto nextbit = (from_node >> (nbits-layer-1)) & 1;
 			size_t nodes_in_prev_layer = std::ceil(static_cast<double>(nodes_in_interval) / (1ULL << (depth-layer)));
 			size_t nodes_in_cur_layer = std::ceil(static_cast<double>(nodes_in_interval) / (1ULL << (depth-layer-1)));
-
-
 			
  			for (i = nextbit, j = nextbit; j < nodes_in_prev_layer-1; ++j, i+=2)
 			{
 				traverse(prgkey, s[1-curlayer][j], &s[curlayer][i]);
-
 			}
 			
 			if (nodes_in_prev_layer > j)
@@ -632,7 +634,6 @@ inline void evaluate_dpfs( size_t db_nitems,  dpfP2 dpfinstance,  const AES_KEY&
 				if (i < nodes_in_cur_layer - 1) 
 				{
 					traverse(prgkey, s[1-curlayer][j], &s[curlayer][i]);
-	
 				}
 			}
 
@@ -658,13 +659,13 @@ inline void evaluate_dpfs( size_t db_nitems,  dpfP2 dpfinstance,  const AES_KEY&
 	 
 	for (size_t i = 0; i < to + 1; ++i)
 	{
-	  Gamma[0] += output[i][0];
+	  Gamma[0] += output[i][0];	// the correction word for duoram update
 	  Gamma[1] += output[i][1]; // the correction word for share conversion
 	}
 		
 	if(party) 
 	{
-	  Gamma[0] = -Gamma[0];
+	  Gamma[0] = -Gamma[0];	 // the correction word for duoram update
 	  Gamma[1] = -Gamma[1];  // the correction word for share conversion
 	}