use common context for ElGamal encrypt/decrypt

Crypto.cpp

@@ -272,9 +272,8 @@ namespace crypto
 	}	
 	
 // ElGamal
-	void ElGamalEncrypt (const uint8_t * key, const uint8_t * data, uint8_t * encrypted, bool zeroPadding)
+	void ElGamalEncrypt (const uint8_t * key, const uint8_t * data, uint8_t * encrypted, BN_CTX * ctx, bool zeroPadding)
 	{
-		BN_CTX * ctx = BN_CTX_new ();
 		BN_CTX_start (ctx);
 		// everything, but a, because a might come from table	
 		BIGNUM * k = BN_CTX_get (ctx);
@@ -324,13 +323,11 @@ namespace crypto
 		}		
 		BN_free (a);
 		BN_CTX_end (ctx);
-		BN_CTX_free (ctx);
 	}
 
 	bool ElGamalDecrypt (const uint8_t * key, const uint8_t * encrypted, 
-		uint8_t * data, bool zeroPadding)
+		uint8_t * data, BN_CTX * ctx, bool zeroPadding)
 	{
-		BN_CTX * ctx = BN_CTX_new ();
 		BN_CTX_start (ctx);
 		BIGNUM * x = BN_CTX_get (ctx), * a = BN_CTX_get (ctx), * b = BN_CTX_get (ctx);
 		BN_bin2bn (key, 256, x);
@@ -343,7 +340,6 @@ namespace crypto
 		uint8_t m[255];
 		bn2buf (b, m, 255); 
 		BN_CTX_end (ctx);
-		BN_CTX_free (ctx);
 		uint8_t hash[32];
 		SHA256 (m + 33, 222, hash);
 		if (memcmp (m + 1, hash, 32))

Crypto.h

@@ -48,8 +48,8 @@ namespace crypto
 	};	
 	
 	// ElGamal
-	void ElGamalEncrypt (const uint8_t * key, const uint8_t * data, uint8_t * encrypted, bool zeroPadding = false);
-	bool ElGamalDecrypt (const uint8_t * key, const uint8_t * encrypted, uint8_t * data, bool zeroPadding = false);
+	void ElGamalEncrypt (const uint8_t * key, const uint8_t * data, uint8_t * encrypted, BN_CTX * ctx, bool zeroPadding = false);
+	bool ElGamalDecrypt (const uint8_t * key, const uint8_t * encrypted, uint8_t * data, BN_CTX * ctx, bool zeroPadding = false);
 	void GenerateElGamalKeyPair (uint8_t * priv, uint8_t * pub);
 
 	// HMAC

Garlic.cpp

@@ -187,7 +187,8 @@ namespace garlic
 			RAND_bytes (elGamal.preIV, 32); // Pre-IV
 			uint8_t iv[32]; // IV is first 16 bytes
 			SHA256(elGamal.preIV, 32, iv); 
-			i2p::crypto::ElGamalEncrypt (m_Destination->GetEncryptionPublicKey (), (uint8_t *)&elGamal, buf, true);			
+			i2p::crypto::ElGamalEncrypt (m_Destination->GetEncryptionPublicKey (), 
+				(uint8_t *)&elGamal, buf, m_Owner->GetBNContext (), true);			
 			m_Encryption.SetIV (iv);
 			buf += 514;
 			len += 514;	
@@ -389,8 +390,14 @@ namespace garlic
 		return size;
 	}
 
+	GarlicDestination::GarlicDestination (): m_NumTags (32) // 32 tags by default
+	{
+		m_Ctx = BN_CTX_new ();
+	} 
+		
 	GarlicDestination::~GarlicDestination ()
 	{
+		BN_CTX_free (m_Ctx);
 	}
 
 	void GarlicDestination::CleanUp ()
@@ -446,7 +453,7 @@ namespace garlic
 		{
 			// tag not found. Use ElGamal
 			ElGamalBlock elGamal;
-			if (length >= 514 && i2p::crypto::ElGamalDecrypt (GetEncryptionPrivateKey (), buf, (uint8_t *)&elGamal, true))
+			if (length >= 514 && i2p::crypto::ElGamalDecrypt (GetEncryptionPrivateKey (), buf, (uint8_t *)&elGamal, m_Ctx, true))
 			{	
 				auto decryption = std::make_shared<i2p::crypto::CBCDecryption>();
 				decryption->SetKey (elGamal.sessionKey);

Garlic.h

@@ -153,11 +153,12 @@ namespace garlic
 	{
 		public:
 
-			GarlicDestination (): m_NumTags (32) {}; // 32 tags by default
+			GarlicDestination ();
 			~GarlicDestination ();
 
 			void CleanUp ();
 			void SetNumTags (int numTags) { m_NumTags = numTags; };	
+			BN_CTX * GetBNContext () const { return m_Ctx; };
 			std::shared_ptr<GarlicRoutingSession> GetRoutingSession (std::shared_ptr<const i2p::data::RoutingDestination> destination, bool attachLeaseSet);	
 			void CleanupExpiredTags ();
 			void RemoveDeliveryStatusSession (uint32_t msgID);
@@ -189,6 +190,7 @@ namespace garlic
 
 		private:
 
+			BN_CTX * m_Ctx;
 			// outgoing sessions
 			int m_NumTags;
 			std::mutex m_SessionsMutex;

I2NPProtocol.cpp

@@ -326,8 +326,9 @@ namespace i2p
 			if (!memcmp (record + BUILD_REQUEST_RECORD_TO_PEER_OFFSET, (const uint8_t *)i2p::context.GetRouterInfo ().GetIdentHash (), 16))
 			{	
 				LogPrint (eLogDebug, "I2NP: Build request record ", i, " is ours");
-			
-				i2p::crypto::ElGamalDecrypt (i2p::context.GetEncryptionPrivateKey (), record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET, clearText);
+				BN_CTX * ctx = BN_CTX_new ();
+				i2p::crypto::ElGamalDecrypt (i2p::context.GetEncryptionPrivateKey (), record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET, clearText, ctx);
+				BN_CTX_free (ctx);
 				// replace record to reply			
 				if (i2p::context.AcceptsTunnels () && 
 					i2p::tunnel::tunnels.GetTransitTunnels ().size () <= g_MaxNumTransitTunnels &&

Tunnel.cpp

@@ -51,6 +51,7 @@ namespace tunnel
 		uint8_t * records = msg->GetPayload () + 1; 
 		TunnelHopConfig * hop = m_Config->GetFirstHop ();
 		int i = 0;
+		BN_CTX * ctx = BN_CTX_new ();
 		while (hop)
 		{
 			uint32_t msgID;
@@ -59,7 +60,7 @@ namespace tunnel
 			else
 				msgID = replyMsgID;
 			int idx = recordIndicies[i];
-			hop->CreateBuildRequestRecord (records + idx*TUNNEL_BUILD_RECORD_SIZE, msgID); 
+			hop->CreateBuildRequestRecord (records + idx*TUNNEL_BUILD_RECORD_SIZE, msgID, ctx); 
 			hop->recordIndex = idx; 
 			i++;
 #ifdef WITH_EVENTS
@@ -67,6 +68,7 @@ namespace tunnel
 #endif
 			hop = hop->next;
 		}
+		BN_CTX_free (ctx);
 #ifdef WITH_EVENTS
 		EmitTunnelEvent("tunnel.build", this, peers);
 #endif

TunnelConfig.h

@@ -83,7 +83,7 @@ namespace tunnel
 			}	
 		}
 
-		void CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID) const
+		void CreateBuildRequestRecord (uint8_t * record, uint32_t replyMsgID, BN_CTX * ctx) const
 		{
 			uint8_t clearText[BUILD_REQUEST_RECORD_CLEAR_TEXT_SIZE];
 			htobe32buf (clearText + BUILD_REQUEST_RECORD_RECEIVE_TUNNEL_OFFSET, tunnelID); 
@@ -101,7 +101,7 @@ namespace tunnel
 			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);
-			i2p::crypto::ElGamalEncrypt (ident->GetEncryptionPublicKey (), clearText, record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET);
+			i2p::crypto::ElGamalEncrypt (ident->GetEncryptionPublicKey (), clearText, record + BUILD_REQUEST_RECORD_ENCRYPTED_OFFSET, ctx);
 			memcpy (record + BUILD_REQUEST_RECORD_TO_PEER_OFFSET, (const uint8_t *)ident->GetIdentHash (), 16);
 		}	
 	};