diff --git a/Telegram/SourceFiles/mtproto/concurrent_sender.cpp b/Telegram/SourceFiles/mtproto/concurrent_sender.cpp
index b2ffb0028..3d484296a 100644
--- a/Telegram/SourceFiles/mtproto/concurrent_sender.cpp
+++ b/Telegram/SourceFiles/mtproto/concurrent_sender.cpp
@@ -111,7 +111,7 @@ auto ConcurrentSender::with_instance(Method &&method)
 
 ConcurrentSender::RequestBuilder::RequestBuilder(
 	not_null<ConcurrentSender*> sender,
-	SecureRequest &&serialized) noexcept
+	details::SerializedRequest &&serialized) noexcept
 : _sender(sender)
 , _serialized(std::move(serialized)) {
 }
diff --git a/Telegram/SourceFiles/mtproto/concurrent_sender.h b/Telegram/SourceFiles/mtproto/concurrent_sender.h
index 5929f800c..68fb22781 100644
--- a/Telegram/SourceFiles/mtproto/concurrent_sender.h
+++ b/Telegram/SourceFiles/mtproto/concurrent_sender.h
@@ -12,6 +12,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/weak_ptr.h"
 #include "base/flat_map.h"
 #include "mtproto/core_types.h"
+#include "mtproto/details/mtproto_serialized_request.h"
 
 #ifndef _DEBUG
 #define MTP_SENDER_USE_GENERIC_HANDLERS
@@ -61,7 +62,7 @@ class ConcurrentSender : public base::has_weak_ptr {
 	protected:
 		RequestBuilder(
 			not_null<ConcurrentSender*> sender,
-			SecureRequest &&serialized) noexcept;
+			details::SerializedRequest &&serialized) noexcept;
 
 		void setToDC(ShiftedDcId dcId) noexcept;
 		void setCanWait(crl::time ms) noexcept;
@@ -74,7 +75,7 @@ class ConcurrentSender : public base::has_weak_ptr {
 
 	private:
 		not_null<ConcurrentSender*> _sender;
-		SecureRequest _serialized;
+		details::SerializedRequest _serialized;
 		ShiftedDcId _dcId = 0;
 		crl::time _canWait = 0;
 
@@ -224,8 +225,8 @@ void ConcurrentSender::RequestBuilder::setFailHandler(
 template <typename Request>
 ConcurrentSender::SpecificRequestBuilder<Request>::SpecificRequestBuilder(
 	not_null<ConcurrentSender*> sender,
-	Request &&request
-) noexcept : RequestBuilder(sender, SecureRequest::Serialize(request)) {
+	Request &&request) noexcept
+: RequestBuilder(sender, details::SerializedRequest::Serialize(request)) {
 }
 
 template <typename Request>
diff --git a/Telegram/SourceFiles/mtproto/connection.cpp b/Telegram/SourceFiles/mtproto/connection.cpp
index e5d5be76a..80f4e478e 100644
--- a/Telegram/SourceFiles/mtproto/connection.cpp
+++ b/Telegram/SourceFiles/mtproto/connection.cpp
@@ -85,11 +85,15 @@ using namespace details;
 		: TemporaryKeyType::Regular;
 }
 
-void wrapInvokeAfter(SecureRequest &to, const SecureRequest &from, const RequestMap &haveSent, int32 skipBeforeRequest = 0) {
+void WrapInvokeAfter(
+		SerializedRequest &to,
+		const SerializedRequest &from,
+		const base::flat_map<mtpMsgId, SerializedRequest> &haveSent,
+		int32 skipBeforeRequest = 0) {
 	const auto afterId = *(mtpMsgId*)(from->after->data() + 4);
-	const auto i = afterId ? haveSent.constFind(afterId) : haveSent.cend();
+	const auto i = afterId ? haveSent.find(afterId) : haveSent.end();
 	int32 size = to->size(), lenInInts = (tl::count_length(from) >> 2), headlen = 4, fulllen = headlen + lenInInts;
-	if (i == haveSent.constEnd()) { // no invoke after or such msg was not sent or was completed recently
+	if (i == haveSent.end()) { // no invoke after or such msg was not sent or was completed recently
 		to->resize(size + fulllen + skipBeforeRequest);
 		if (skipBeforeRequest) {
 			memcpy(to->data() + size, from->constData() + 4, headlen * sizeof(mtpPrime));
@@ -229,41 +233,41 @@ int16 ConnectionPrivate::getProtocolDcId() const {
 }
 
 void ConnectionPrivate::checkSentRequests() {
-	QVector<mtpMsgId> removingIds; // remove very old (10 minutes) containers and resend requests
+	// Remove very old (10 minutes) containers and resend requests.
+	auto removingIds = std::vector<mtpMsgId>();
 	auto requesting = false;
 	{
 		QReadLocker locker(_sessionData->haveSentMutex());
 		auto &haveSent = _sessionData->haveSentMap();
 		const auto haveSentCount = haveSent.size();
-		auto ms = crl::now();
-		for (auto i = haveSent.begin(), e = haveSent.end(); i != e; ++i) {
-			auto &req = i.value();
-			if (req->msDate > 0) {
-				if (req->msDate + kCheckSentRequestTimeout < ms) {
-					// Need to check state.
-					req->msDate = ms;
-					if (_stateRequestData.emplace(i.key()).second) {
-						requesting = true;
-					}
+		auto now = crl::now();
+		for (const auto &[msgId, request] : haveSent) {
+			if (request.isStateRequest()) {
+				continue;
+			} else if (request.isSentContainer()) {
+				if (base::unixtime::now()
+					> int32(msgId >> 32) + kContainerLives) {
+					removingIds.push_back(msgId);
+				}
+			} else if (request->lastSentTime + kCheckSentRequestTimeout
+				< now) {
+				// Need to check state.
+				request->lastSentTime = now;
+				if (_stateRequestData.emplace(msgId).second) {
+					requesting = true;
 				}
-			} else if (base::unixtime::now()
-				> int32(i.key() >> 32) + kContainerLives) {
-				removingIds.reserve(haveSentCount);
-				removingIds.push_back(i.key());
 			}
 		}
 	}
 	if (requesting) {
 		_sessionData->queueSendAnything(kSendStateRequestWaiting);
 	}
-	if (!removingIds.isEmpty()) {
+	if (!removingIds.empty()) {
 		QWriteLocker locker(_sessionData->haveSentMutex());
 		auto &haveSent = _sessionData->haveSentMap();
-		for (uint32 i = 0, l = removingIds.size(); i < l; ++i) {
-			auto j = haveSent.find(removingIds[i]);
-			if (j != haveSent.cend()) {
-				Assert(!j.value()->requestId);
-				haveSent.erase(j);
+		for (const auto msgId : removingIds) {
+			if (const auto removed = haveSent.take(msgId)) {
+				Assert(!(*removed)->requestId);
 			}
 		}
 	}
@@ -436,7 +440,7 @@ bool ConnectionPrivate::markSessionAsStarted() {
 }
 
 mtpMsgId ConnectionPrivate::prepareToSend(
-		SecureRequest &request,
+		SerializedRequest &request,
 		mtpMsgId currentLastId,
 		bool forceNewMsgId) {
 	Expects(request->size() > 8);
@@ -460,7 +464,7 @@ mtpMsgId ConnectionPrivate::prepareToSend(
 	return currentLastId;
 }
 
-mtpMsgId ConnectionPrivate::replaceMsgId(SecureRequest &request, mtpMsgId newId) {
+mtpMsgId ConnectionPrivate::replaceMsgId(SerializedRequest &request, mtpMsgId newId) {
 	Expects(request->size() > 8);
 
 	const auto oldMsgId = request.getMsgId();
@@ -472,11 +476,14 @@ mtpMsgId ConnectionPrivate::replaceMsgId(SecureRequest &request, mtpMsgId newId)
 
 	while (_resendingIds.contains(newId)
 		|| _ackedIds.contains(newId)
-		|| haveSent.constFind(newId) != haveSent.cend()) {
+		|| haveSent.contains(newId)) {
 		newId = base::unixtime::mtproto_msg_id();
 	}
 
-	MTP_LOG(_shiftedDcId, ("[r%1] msg_id %2 -> %3").arg(request->requestId).arg(oldMsgId).arg(newId));
+	MTP_LOG(_shiftedDcId, ("[r%1] msg_id %2 -> %3"
+		).arg(request->requestId
+		).arg(oldMsgId
+		).arg(newId));
 
 	const auto i = _resendingIds.find(oldMsgId);
 	if (i != _resendingIds.end()) {
@@ -486,24 +493,23 @@ mtpMsgId ConnectionPrivate::replaceMsgId(SecureRequest &request, mtpMsgId newId)
 	}
 
 	const auto j = _ackedIds.find(oldMsgId);
-	if (j != _ackedIds.cend()) {
+	if (j != _ackedIds.end()) {
 		const auto requestId = j->second;
 		_ackedIds.erase(j);
 		_ackedIds.emplace(newId, requestId);
 	}
 
 	const auto k = haveSent.find(oldMsgId);
-	if (k != haveSent.cend()) {
-		const auto req = k.value();
+	if (k != haveSent.end()) {
+		const auto request = k->second;
 		haveSent.erase(k);
-		haveSent.insert(newId, req);
+		haveSent.emplace(newId, request);
 	}
 
-	for (auto l = haveSent.begin(); l != haveSent.cend(); ++l) {
-		const auto req = l.value();
-		if (req.isSentContainer()) {
-			const auto ids = (mtpMsgId *)(req->data() + 8);
-			for (uint32 i = 0, l = (req->size() - 8) >> 1; i < l; ++i) {
+	for (const auto &[requestId, sent] : haveSent) {
+		if (sent.isSentContainer()) {
+			const auto ids = (mtpMsgId *)(sent->data() + 8);
+			for (uint32 i = 0, l = (sent->size() - 8) >> 1; i < l; ++i) {
 				if (ids[i] == oldMsgId) {
 					ids[i] = newId;
 				}
@@ -517,11 +523,11 @@ mtpMsgId ConnectionPrivate::replaceMsgId(SecureRequest &request, mtpMsgId newId)
 }
 
 mtpMsgId ConnectionPrivate::placeToContainer(
-		SecureRequest &toSendRequest,
+		SerializedRequest &toSendRequest,
 		mtpMsgId &bigMsgId,
 		bool forceNewMsgId,
 		mtpMsgId *&haveSentArr,
-		SecureRequest &req) {
+		SerializedRequest &req) {
 	const auto msgId = prepareToSend(req, bigMsgId, forceNewMsgId);
 	if (msgId >= bigMsgId) {
 		bigMsgId = base::unixtime::mtproto_msg_id();
@@ -560,28 +566,28 @@ void ConnectionPrivate::tryToSend() {
 		_keyCreator->restartBinder();
 	}
 
-	auto pingRequest = SecureRequest();
-	auto ackRequest = SecureRequest();
-	auto resendRequest = SecureRequest();
-	auto stateRequest = SecureRequest();
-	auto httpWaitRequest = SecureRequest();
-	auto bindDcKeyRequest = SecureRequest();
+	auto pingRequest = SerializedRequest();
+	auto ackRequest = SerializedRequest();
+	auto resendRequest = SerializedRequest();
+	auto stateRequest = SerializedRequest();
+	auto httpWaitRequest = SerializedRequest();
+	auto bindDcKeyRequest = SerializedRequest();
 	if (_pingIdToSend) {
 		if (sendOnlyFirstPing || !isMainSession) {
 			DEBUG_LOG(("MTP Info: sending ping, ping_id: %1"
 				).arg(_pingIdToSend));
-			pingRequest = SecureRequest::Serialize(MTPPing(
+			pingRequest = SerializedRequest::Serialize(MTPPing(
 				MTP_long(_pingIdToSend)
 			));
 		} else {
 			DEBUG_LOG(("MTP Info: sending ping_delay_disconnect, "
 				"ping_id: %1").arg(_pingIdToSend));
-			pingRequest = SecureRequest::Serialize(MTPPing_delay_disconnect(
+			pingRequest = SerializedRequest::Serialize(MTPPing_delay_disconnect(
 				MTP_long(_pingIdToSend),
 				MTP_int(kPingDelayDisconnect)));
 			_pingSender.callOnce(kPingSendAfterForce);
 		}
-		_pingSendAt = pingRequest->msDate + kPingSendAfter;
+		_pingSendAt = pingRequest->lastSentTime + kPingSendAfter;
 		_pingId = base::take(_pingIdToSend);
 	} else if (!sendAll) {
 		DEBUG_LOG(("MTP Info: dc %1 sending only service or bind."
@@ -594,12 +600,12 @@ void ConnectionPrivate::tryToSend() {
 
 	if (!sendOnlyFirstPing) {
 		if (!_ackRequestData.isEmpty()) {
-			ackRequest = SecureRequest::Serialize(MTPMsgsAck(
+			ackRequest = SerializedRequest::Serialize(MTPMsgsAck(
 				MTP_msgs_ack(MTP_vector<MTPlong>(
 					base::take(_ackRequestData)))));
 		}
 		if (!_resendRequestData.isEmpty()) {
-			resendRequest = SecureRequest::Serialize(MTPMsgResendReq(
+			resendRequest = SerializedRequest::Serialize(MTPMsgResendReq(
 				MTP_msg_resend_req(MTP_vector<MTPlong>(
 					base::take(_resendRequestData)))));
 		}
@@ -609,13 +615,13 @@ void ConnectionPrivate::tryToSend() {
 			for (const auto id : base::take(_stateRequestData)) {
 				ids.push_back(MTP_long(id));
 			}
-			stateRequest = SecureRequest::Serialize(MTPMsgsStateReq(
+			stateRequest = SerializedRequest::Serialize(MTPMsgsStateReq(
 				MTP_msgs_state_req(MTP_vector<MTPlong>(ids))));
 			// Add to haveSent / _ackedIds, but don't add to requestMap.
 			stateRequest->requestId = GetNextRequestId();
 		}
 		if (_connection->usingHttpWait()) {
-			httpWaitRequest = SecureRequest::Serialize(MTPHttpWait(
+			httpWaitRequest = SerializedRequest::Serialize(MTPHttpWait(
 				MTP_http_wait(MTP_int(100), MTP_int(30), MTP_int(25000))));
 		}
 		if (!_bindMsgId && _keyCreator && _keyCreator->readyToBind()) {
@@ -631,7 +637,7 @@ void ConnectionPrivate::tryToSend() {
 		}
 	}
 
-	MTPInitConnection<SecureRequest> initWrapper;
+	MTPInitConnection<SerializedRequest> initWrapper;
 	int32 initSize = 0, initSizeInInts = 0;
 	if (needsLayer) {
 		Assert(_connectionOptions != nullptr);
@@ -660,8 +666,8 @@ void ConnectionPrivate::tryToSend() {
 				MTP_string(_connectionOptions->proxy.host),
 				MTP_int(_connectionOptions->proxy.port))
 			: MTPInputClientProxy();
-		using Flag = MTPInitConnection<SecureRequest>::Flag;
-		initWrapper = MTPInitConnection<SecureRequest>(
+		using Flag = MTPInitConnection<SerializedRequest>::Flag;
+		initWrapper = MTPInitConnection<SerializedRequest>(
 			MTP_flags(mtprotoProxy ? Flag::f_proxy : Flag(0)),
 			MTP_int(ApiId),
 			MTP_string(deviceModel),
@@ -671,25 +677,22 @@ void ConnectionPrivate::tryToSend() {
 			MTP_string(langPackName),
 			MTP_string(cloudLangCode),
 			clientProxyFields,
-			SecureRequest());
+			SerializedRequest());
 		initSizeInInts = (tl::count_length(initWrapper) >> 2) + 2;
 		initSize = initSizeInInts * sizeof(mtpPrime);
 	}
 
 	bool needAnyResponse = false;
-	SecureRequest toSendRequest;
+	SerializedRequest toSendRequest;
 	{
 		QWriteLocker locker1(_sessionData->toSendMutex());
 
-		auto toSendDummy = PreRequestMap();
+		auto toSendDummy = base::flat_map<mtpRequestId, SerializedRequest>();
 		auto &toSend = sendAll
 			? _sessionData->toSendMap()
 			: toSendDummy;
 		if (!sendAll) {
 			locker1.unlock();
-		} else {
-			int time = crl::now();
-			int now = crl::now();
 		}
 
 		uint32 toSendCount = toSend.size();
@@ -716,8 +719,8 @@ void ConnectionPrivate::tryToSend() {
 			? httpWaitRequest
 			: bindDcKeyRequest
 			? bindDcKeyRequest
-			: toSend.cbegin().value();
-		if (toSendCount == 1 && first->msDate > 0) { // if can send without container
+			: toSend.begin()->second;
+		if (toSendCount == 1 && !first->forceSendInContainer) {
 			toSendRequest = first;
 			if (sendAll) {
 				toSend.clear();
@@ -740,27 +743,27 @@ void ConnectionPrivate::tryToSend() {
 
 			if (toSendRequest->requestId) {
 				if (toSendRequest.needAck()) {
-					toSendRequest->msDate = toSendRequest.isStateRequest() ? 0 : crl::now();
+					toSendRequest->lastSentTime = crl::now();
 
 					QWriteLocker locker2(_sessionData->haveSentMutex());
 					auto &haveSent = _sessionData->haveSentMap();
-					haveSent.insert(msgId, toSendRequest);
+					haveSent.emplace(msgId, toSendRequest);
 
 					const auto wrapLayer = needsLayer && toSendRequest->needsLayer;
 					if (toSendRequest->after) {
 						const auto toSendSize = tl::count_length(toSendRequest) >> 2;
-						auto wrappedRequest = SecureRequest::Prepare(
+						auto wrappedRequest = SerializedRequest::Prepare(
 							toSendSize,
 							toSendSize + 3);
 						wrappedRequest->resize(4);
 						memcpy(wrappedRequest->data(), toSendRequest->constData(), 4 * sizeof(mtpPrime));
-						wrapInvokeAfter(wrappedRequest, toSendRequest, haveSent);
+						WrapInvokeAfter(wrappedRequest, toSendRequest, haveSent);
 						toSendRequest = std::move(wrappedRequest);
 					}
 					if (wrapLayer) {
 						const auto noWrapSize = (tl::count_length(toSendRequest) >> 2);
 						const auto toSendSize = noWrapSize + initSizeInInts;
-						auto wrappedRequest = SecureRequest::Prepare(toSendSize);
+						auto wrappedRequest = SerializedRequest::Prepare(toSendSize);
 						memcpy(wrappedRequest->data(), toSendRequest->constData(), 7 * sizeof(mtpPrime)); // all except length
 						wrappedRequest->push_back(mtpc_invokeWithLayer);
 						wrappedRequest->push_back(internal::CurrentLayer);
@@ -784,9 +787,9 @@ void ConnectionPrivate::tryToSend() {
 			if (stateRequest) containerSize += stateRequest.messageSize();
 			if (httpWaitRequest) containerSize += httpWaitRequest.messageSize();
 			if (bindDcKeyRequest) containerSize += bindDcKeyRequest.messageSize();
-			for (auto i = toSend.begin(), e = toSend.end(); i != e; ++i) {
-				containerSize += i.value().messageSize();
-				if (needsLayer && i.value()->needsLayer) {
+			for (const auto &[requestId, request] : toSend) {
+				containerSize += request.messageSize();
+				if (needsLayer && request->needsLayer) {
 					containerSize += initSizeInInts;
 					willNeedInit = true;
 				}
@@ -799,7 +802,7 @@ void ConnectionPrivate::tryToSend() {
 				initWrapper.write<mtpBuffer>(initSerialized);
 			}
 			// prepare container + each in invoke after
-			toSendRequest = SecureRequest::Prepare(
+			toSendRequest = SerializedRequest::Prepare(
 				containerSize,
 				containerSize + 3 * toSend.size());
 			toSendRequest->push_back(mtpc_msg_container);
@@ -813,9 +816,8 @@ void ConnectionPrivate::tryToSend() {
 			auto &haveSent = _sessionData->haveSentMap();
 
 			// prepare "request-like" wrap for msgId vector
-			auto haveSentIdsWrap = SecureRequest::Prepare(idsWrapSize);
-			haveSentIdsWrap->msDate = 0; // Container: msDate = 0, seqNo = 0.
-			haveSentIdsWrap->requestId = 0;
+			auto haveSentIdsWrap = SerializedRequest::Prepare(idsWrapSize);
+			haveSentIdsWrap->isContainerIdsWrap = true;
 			haveSentIdsWrap->resize(haveSentIdsWrap->size() + idsWrapSize);
 			auto haveSentArr = (mtpMsgId*)(haveSentIdsWrap->data() + 8);
 
@@ -840,10 +842,9 @@ void ConnectionPrivate::tryToSend() {
 			if (resendRequest || stateRequest) {
 				needAnyResponse = true;
 			}
-			for (auto i = toSend.begin(), e = toSend.end(); i != e; ++i) {
-				auto &req = i.value();
+			for (auto &[requestId, request] : toSend) {
 				const auto msgId = prepareToSend(
-					req,
+					request,
 					bigMsgId,
 					forceNewMsgId);
 				if (msgId >= bigMsgId) {
@@ -851,44 +852,43 @@ void ConnectionPrivate::tryToSend() {
 				}
 				*(haveSentArr++) = msgId;
 				bool added = false;
-				if (req->requestId) {
-					if (req.needAck()) {
-						req->msDate = req.isStateRequest() ? 0 : crl::now();
-						int32 reqNeedsLayer = (needsLayer && req->needsLayer) ? toSendRequest->size() : 0;
-						if (req->after) {
-							wrapInvokeAfter(toSendRequest, req, haveSent, reqNeedsLayer ? initSizeInInts : 0);
+				if (request->requestId) {
+					if (request.needAck()) {
+						request->lastSentTime = crl::now();
+						int32 reqNeedsLayer = (needsLayer && request->needsLayer) ? toSendRequest->size() : 0;
+						if (request->after) {
+							WrapInvokeAfter(toSendRequest, request, haveSent, reqNeedsLayer ? initSizeInInts : 0);
 							if (reqNeedsLayer) {
 								memcpy(toSendRequest->data() + reqNeedsLayer + 4, initSerialized.constData(), initSize);
 								*(toSendRequest->data() + reqNeedsLayer + 3) += initSize;
 							}
 							added = true;
 						} else if (reqNeedsLayer) {
-							toSendRequest->resize(reqNeedsLayer + initSizeInInts + req.messageSize());
-							memcpy(toSendRequest->data() + reqNeedsLayer, req->constData() + 4, 4 * sizeof(mtpPrime));
+							toSendRequest->resize(reqNeedsLayer + initSizeInInts + request.messageSize());
+							memcpy(toSendRequest->data() + reqNeedsLayer, request->constData() + 4, 4 * sizeof(mtpPrime));
 							memcpy(toSendRequest->data() + reqNeedsLayer + 4, initSerialized.constData(), initSize);
-							memcpy(toSendRequest->data() + reqNeedsLayer + 4 + initSizeInInts, req->constData() + 8, tl::count_length(req));
+							memcpy(toSendRequest->data() + reqNeedsLayer + 4 + initSizeInInts, request->constData() + 8, tl::count_length(request));
 							*(toSendRequest->data() + reqNeedsLayer + 3) += initSize;
 							added = true;
 						}
 						Assert(!haveSent.contains(msgId));
-						haveSent.insert(msgId, req);
+						haveSent.emplace(msgId, request);
 
 						needAnyResponse = true;
 					} else {
-						_ackedIds.emplace(msgId, req->requestId);
+						_ackedIds.emplace(msgId, request->requestId);
 					}
 				}
 				if (!added) {
-					uint32 from = toSendRequest->size(), len = req.messageSize();
+					uint32 from = toSendRequest->size(), len = request.messageSize();
 					toSendRequest->resize(from + len);
-					memcpy(toSendRequest->data() + from, req->constData() + 4, len * sizeof(mtpPrime));
+					memcpy(toSendRequest->data() + from, request->constData() + 4, len * sizeof(mtpPrime));
 				}
 			}
 			if (stateRequest) {
-				mtpMsgId msgId = placeToContainer(toSendRequest, bigMsgId, forceNewMsgId, haveSentArr, stateRequest);
-				stateRequest->msDate = 0; // 0 for state request, do not request state of it
+				const auto msgId = placeToContainer(toSendRequest, bigMsgId, forceNewMsgId, haveSentArr, stateRequest);
 				Assert(!haveSent.contains(msgId));
-				haveSent.insert(msgId, stateRequest);
+				haveSent.emplace(msgId, stateRequest);
 			}
 			if (resendRequest) placeToContainer(toSendRequest, bigMsgId, forceNewMsgId, haveSentArr, resendRequest);
 			if (ackRequest) placeToContainer(toSendRequest, bigMsgId, forceNewMsgId, haveSentArr, ackRequest);
@@ -899,9 +899,8 @@ void ConnectionPrivate::tryToSend() {
 				bigMsgId,
 				forceNewMsgId);
 			*(mtpMsgId*)(haveSentIdsWrap->data() + 4) = containerMsgId;
-			(*haveSentIdsWrap)[6] = 0; // for container, msDate = 0, seqNo = 0
 			Assert(!haveSent.contains(containerMsgId));
-			haveSent.insert(containerMsgId, haveSentIdsWrap);
+			haveSent.emplace(containerMsgId, haveSentIdsWrap);
 			toSend.clear();
 		}
 	}
@@ -1370,7 +1369,8 @@ void ConnectionPrivate::handleReceived() {
 		}
 
 		auto lock = QReadLocker(_sessionData->haveReceivedMutex());
-		const auto tryToReceive = !_sessionData->haveReceivedResponses().isEmpty() || !_sessionData->haveReceivedUpdates().isEmpty();
+		const auto tryToReceive = !_sessionData->haveReceivedResponses().empty()
+			|| !_sessionData->haveReceivedUpdates().empty();
 		lock.unlock();
 
 		if (tryToReceive) {
@@ -1521,16 +1521,16 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 				|| (errorCode == 64); // bad container
 			if (errorCode == 64) { // bad container!
 				if (Logs::DebugEnabled()) {
-					SecureRequest request;
+					SerializedRequest request;
 					{
 						QWriteLocker locker(_sessionData->haveSentMutex());
 						auto &haveSent = _sessionData->haveSentMap();
 
-						const auto i = haveSent.constFind(resendId);
-						if (i == haveSent.cend()) {
+						const auto i = haveSent.find(resendId);
+						if (i == haveSent.end()) {
 							LOG(("Message Error: Container not found!"));
 						} else {
-							request = i.value();
+							request = i->second;
 						}
 					}
 					if (request) {
@@ -1626,53 +1626,6 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 		resend(resendId);
 	} return HandleResult::Success;
 
-	case mtpc_msgs_state_req: {
-		if (badTime) {
-			DEBUG_LOG(("Message Info: skipping with bad time..."));
-			return HandleResult::Ignored;
-		}
-		MTPMsgsStateReq msg;
-		if (!msg.read(from, end)) {
-			return HandleResult::ParseError;
-		}
-		auto &ids = msg.c_msgs_state_req().vmsg_ids().v;
-		auto idsCount = ids.size();
-		DEBUG_LOG(("Message Info: msgs_state_req received, ids: %1").arg(LogIdsVector(ids)));
-		if (!idsCount) return HandleResult::Success;
-
-		QByteArray info(idsCount, Qt::Uninitialized);
-		{
-			const auto minRecv = _receivedMessageIds.min();
-			const auto maxRecv = _receivedMessageIds.max();
-			for (uint32 i = 0, l = idsCount; i < l; ++i) {
-				char state = 0;
-				uint64 reqMsgId = ids[i].v;
-				if (reqMsgId < minRecv) {
-					state |= 0x01;
-				} else if (reqMsgId > maxRecv) {
-					state |= 0x03;
-				} else {
-					auto msgIdState = _receivedMessageIds.lookup(reqMsgId);
-					if (msgIdState == ReceivedIdsManager::State::NotFound) {
-						state |= 0x02;
-					} else {
-						state |= 0x04;
-						if (_ackedIds.contains(reqMsgId)) {
-							state |= 0x80; // we know, that server knows, that we received request
-						}
-						if (msgIdState == ReceivedIdsManager::State::NeedsAck) { // need ack, so we sent ack
-							state |= 0x08;
-						} else {
-							state |= 0x10;
-						}
-					}
-				}
-				info[i] = state;
-			}
-		}
-		_sessionData->queueSendMsgsStateInfo(msgId, info);
-	} return HandleResult::Success;
-
 	case mtpc_msgs_state_info: {
 		MTPMsgsStateInfo msg;
 		if (!msg.read(from, end)) {
@@ -1684,12 +1637,12 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 		auto &states = data.vinfo().v;
 
 		DEBUG_LOG(("Message Info: msg state received, msgId %1, reqMsgId: %2, HEX states %3").arg(msgId).arg(reqMsgId).arg(Logs::mb(states.data(), states.length()).str()));
-		SecureRequest requestBuffer;
+		SerializedRequest requestBuffer;
 		{ // find this request in session-shared sent requests map
 			QReadLocker locker(_sessionData->haveSentMutex());
 			const auto &haveSent = _sessionData->haveSentMap();
-			const auto replyTo = haveSent.constFind(reqMsgId);
-			if (replyTo == haveSent.cend()) { // do not look in toResend, because we do not resend msgs_state_req requests
+			const auto replyTo = haveSent.find(reqMsgId);
+			if (replyTo == haveSent.end()) { // do not look in toResend, because we do not resend msgs_state_req requests
 				DEBUG_LOG(("Message Error: such message was not sent recently %1").arg(reqMsgId));
 				return (badTime ? HandleResult::Ignored : HandleResult::Success);
 			}
@@ -1703,7 +1656,7 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 
 				badTime = false;
 			}
-			requestBuffer = replyTo.value();
+			requestBuffer = replyTo->second;
 		}
 		QVector<MTPlong> toAckReq(1, MTP_long(reqMsgId)), toAck;
 		requestsAcked(toAck, true);
@@ -1809,7 +1762,7 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 		if (from + 3 > end) {
 			return HandleResult::ParseError;
 		}
-		auto response = SerializedMessage();
+		auto response = mtpBuffer();
 
 		MTPlong reqMsgId;
 		if (!reqMsgId.read(++from, end)) {
@@ -1861,7 +1814,7 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 		if (requestId && requestId != mtpRequestId(0xFFFFFFFF)) {
 			// Save rpc_result for processing in the main thread.
 			QWriteLocker locker(_sessionData->haveReceivedMutex());
-			_sessionData->haveReceivedResponses().insert(requestId, response);
+			_sessionData->haveReceivedResponses().emplace(requestId, response);
 		} else {
 			DEBUG_LOG(("RPC Info: requestId not found for msgId %1").arg(requestMsgId));
 		}
@@ -1893,11 +1846,11 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 			QReadLocker locker(_sessionData->haveSentMutex());
 			const auto &haveSent = _sessionData->haveSentMap();
 			toResend.reserve(haveSent.size());
-			for (auto i = haveSent.cbegin(), e = haveSent.cend(); i != e; ++i) {
-				if (i.key() >= firstMsgId) {
+			for (const auto &[msgId, request] : haveSent) {
+				if (msgId >= firstMsgId) {
 					break;
-				} else if (i.value()->requestId) {
-					toResend.push_back(i.key());
+				} else if (request->requestId) {
+					toResend.push_back(msgId);
 				}
 			}
 		}
@@ -1910,7 +1863,7 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 
 		// Notify main process about new session - need to get difference.
 		QWriteLocker locker(_sessionData->haveReceivedMutex());
-		_sessionData->haveReceivedUpdates().push_back(SerializedMessage(update));
+		_sessionData->haveReceivedUpdates().push_back(mtpBuffer(update));
 	} return HandleResult::Success;
 
 	case mtpc_pong: {
@@ -1957,7 +1910,7 @@ ConnectionPrivate::HandleResult ConnectionPrivate::handleOneReceived(
 
 		// Notify main process about the new updates.
 		QWriteLocker locker(_sessionData->haveReceivedMutex());
-		_sessionData->haveReceivedUpdates().push_back(SerializedMessage(update));
+		_sessionData->haveReceivedUpdates().push_back(mtpBuffer(update));
 	} else {
 		LOG(("Message Error: unexpected updates in dcType: %1"
 			).arg(static_cast<int>(_currentDcType)));
@@ -2075,27 +2028,27 @@ void ConnectionPrivate::requestsAcked(const QVector<MTPlong> &ids, bool byRespon
 		for (uint32 i = 0; i < idsCount; ++i) {
 			mtpMsgId msgId = ids[i].v;
 			const auto req = haveSent.find(msgId);
-			if (req != haveSent.cend()) {
-				if (!req.value()->msDate) {
+			if (req != haveSent.end()) {
+				if (req->second.isSentContainer()) {
 					DEBUG_LOG(("Message Info: container ack received, msgId %1").arg(ids[i].v));
-					uint32 inContCount = ((*req)->size() - 8) / 2;
-					const mtpMsgId *inContId = (const mtpMsgId *)(req.value()->constData() + 8);
+					uint32 inContCount = (req->second->size() - 8) / 2;
+					const mtpMsgId *inContId = (const mtpMsgId *)(req->second->constData() + 8);
 					toAckMore.reserve(toAckMore.size() + inContCount);
 					for (uint32 j = 0; j < inContCount; ++j) {
 						toAckMore.push_back(MTP_long(*(inContId++)));
 					}
 					haveSent.erase(req);
 				} else {
-					mtpRequestId reqId = req.value()->requestId;
+					const auto requestId = req->second->requestId;
 					bool moveToAcked = byResponse;
 					if (!moveToAcked) { // ignore ACK, if we need a response (if we have a handler)
-						moveToAcked = !_instance->hasCallbacks(reqId);
+						moveToAcked = !_instance->hasCallbacks(requestId);
 					}
 					if (moveToAcked) {
-						_ackedIds.emplace(msgId, reqId);
+						_ackedIds.emplace(msgId, requestId);
 						haveSent.erase(req);
 					} else {
-						DEBUG_LOG(("Message Info: ignoring ACK for msgId %1 because request %2 requires a response").arg(msgId).arg(reqId));
+						DEBUG_LOG(("Message Info: ignoring ACK for msgId %1 because request %2 requires a response").arg(msgId).arg(requestId));
 					}
 				}
 			} else {
@@ -2112,9 +2065,9 @@ void ConnectionPrivate::requestsAcked(const QVector<MTPlong> &ids, bool byRespon
 						auto &toSend = _sessionData->toSendMap();
 						const auto req = toSend.find(reqId);
 						if (req != toSend.cend()) {
-							_ackedIds.emplace(msgId, req.value()->requestId);
-							if (req.value()->requestId != reqId) {
-								DEBUG_LOG(("Message Error: for msgId %1 found resent request, requestId %2, contains requestId %3").arg(msgId).arg(reqId).arg(req.value()->requestId));
+							_ackedIds.emplace(msgId, req->second->requestId);
+							if (req->second->requestId != reqId) {
+								DEBUG_LOG(("Message Error: for msgId %1 found resent request, requestId %2, contains requestId %3").arg(msgId).arg(reqId).arg(req->second->requestId));
 							} else {
 								DEBUG_LOG(("Message Info: acked msgId %1 that was prepared to resend, requestId %2").arg(msgId).arg(reqId));
 							}
@@ -2172,9 +2125,7 @@ void ConnectionPrivate::handleMsgsStates(const QVector<MTPlong> &ids, const QByt
 		uint64 requestMsgId = ids[i].v;
 		{
 			QReadLocker locker(_sessionData->haveSentMutex());
-			const auto &haveSent = _sessionData->haveSentMap();
-			const auto haveSentEnd = haveSent.cend();
-			if (haveSent.find(requestMsgId) == haveSentEnd) {
+			if (!_sessionData->haveSentMap().contains(requestMsgId)) {
 				DEBUG_LOG(("Message Info: state was received for msgId %1, but request is not found, looking in resent requests...").arg(requestMsgId));
 				const auto reqIt = _resendingIds.find(requestMsgId);
 				if (reqIt != _resendingIds.cend()) {
@@ -2226,7 +2177,7 @@ void ConnectionPrivate::resend(
 	if (i == haveSent.end()) {
 		return;
 	}
-	auto request = i.value();
+	auto request = i->second;
 	haveSent.erase(i);
 	lock.unlock();
 
@@ -2238,11 +2189,12 @@ void ConnectionPrivate::resend(
 			resend(ids[i], -1, true);
 		}
 	} else if (!request.isStateRequest()) {
-		request->msDate = forceContainer ? 0 : crl::now();
+		request->lastSentTime = crl::now();
+		request->forceSendInContainer = forceContainer;
 		_resendingIds.emplace(msgId, request->requestId);
 		{
 			QWriteLocker locker(_sessionData->toSendMutex());
-			_sessionData->toSendMap().insert(request->requestId, request);
+			_sessionData->toSendMap().emplace(request->requestId, request);
 		}
 	}
 }
@@ -2253,9 +2205,9 @@ void ConnectionPrivate::resendAll() {
 	auto lock = QReadLocker(_sessionData->haveSentMutex());
 	const auto &haveSent = _sessionData->haveSentMap();
 	toResend.reserve(haveSent.size());
-	for (auto i = haveSent.cbegin(), e = haveSent.cend(); i != e; ++i) {
-		if (!i.value().isSentContainer()) {
-			toResend.push_back(i.key());
+	for (const auto &[msgId, request] : haveSent) {
+		if (!request.isSentContainer() && !request.isStateRequest()) {
+			toResend.push_back(msgId);
 		}
 	}
 	lock.unlock();
@@ -2581,7 +2533,7 @@ void ConnectionPrivate::destroyTemporaryKey() {
 }
 
 bool ConnectionPrivate::sendSecureRequest(
-		SecureRequest &&request,
+		SerializedRequest &&request,
 		bool needAnyResponse) {
 #ifdef TDESKTOP_MTPROTO_OLD
 	const auto oldPadding = true;
@@ -2671,10 +2623,10 @@ mtpRequestId ConnectionPrivate::wasSent(mtpMsgId msgId) const {
 	{
 		QReadLocker locker(_sessionData->haveSentMutex());
 		const auto &haveSent = _sessionData->haveSentMap();
-		const auto i = haveSent.constFind(msgId);
-		if (i != haveSent.cend()) {
-			return i.value()->requestId
-				? i.value()->requestId
+		const auto i = haveSent.find(msgId);
+		if (i != haveSent.end()) {
+			return i->second->requestId
+				? i->second->requestId
 				: mtpRequestId(0xFFFFFFFF);
 		}
 	}
diff --git a/Telegram/SourceFiles/mtproto/connection.h b/Telegram/SourceFiles/mtproto/connection.h
index 36c5706d3..2715bb640 100644
--- a/Telegram/SourceFiles/mtproto/connection.h
+++ b/Telegram/SourceFiles/mtproto/connection.h
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 #include "mtproto/details/mtproto_received_ids_manager.h"
+#include "mtproto/details/mtproto_serialized_request.h"
 #include "mtproto/mtproto_auth_key.h"
 #include "mtproto/dc_options.h"
 #include "mtproto/connection_abstract.h"
@@ -139,18 +140,22 @@ private:
 	void checkSentRequests();
 
 	mtpMsgId placeToContainer(
-		SecureRequest &toSendRequest,
+		details::SerializedRequest &toSendRequest,
 		mtpMsgId &bigMsgId,
 		bool forceNewMsgId,
 		mtpMsgId *&haveSentArr,
-		SecureRequest &req);
+		details::SerializedRequest &req);
 	mtpMsgId prepareToSend(
-		SecureRequest &request,
+		details::SerializedRequest &request,
 		mtpMsgId currentLastId,
 		bool forceNewMsgId);
-	mtpMsgId replaceMsgId(SecureRequest &request, mtpMsgId newId);
+	mtpMsgId replaceMsgId(
+		details::SerializedRequest &request,
+		mtpMsgId newId);
 
-	bool sendSecureRequest(SecureRequest &&request, bool needAnyResponse);
+	bool sendSecureRequest(
+		details::SerializedRequest &&request,
+		bool needAnyResponse);
 	mtpRequestId wasSent(mtpMsgId msgId) const;
 
 	[[nodiscard]] HandleResult handleOneReceived(const mtpPrime *from, const mtpPrime *end, uint64 msgId, int32 serverTime, uint64 serverSalt, bool badTime);
diff --git a/Telegram/SourceFiles/mtproto/core_types.h b/Telegram/SourceFiles/mtproto/core_types.h
index 37c84a16d..93724f611 100644
--- a/Telegram/SourceFiles/mtproto/core_types.h
+++ b/Telegram/SourceFiles/mtproto/core_types.h
@@ -122,102 +122,6 @@ static const mtpTypeId mtpLayers[] = {
 };
 static const uint32 mtpLayerMaxSingle = sizeof(mtpLayers) / sizeof(mtpLayers[0]);
 
-namespace MTP {
-namespace details {
-
-struct SecureRequestCreateTag {
-};
-
-} // namespace details
-
-class SecureRequestData;
-class SecureRequest {
-public:
-	SecureRequest() = default;
-
-	static constexpr auto kSaltInts = 2;
-	static constexpr auto kSessionIdInts = 2;
-	static constexpr auto kMessageIdPosition = kSaltInts + kSessionIdInts;
-	static constexpr auto kMessageIdInts = 2;
-	static constexpr auto kSeqNoPosition = kMessageIdPosition
-		+ kMessageIdInts;
-	static constexpr auto kSeqNoInts = 1;
-	static constexpr auto kMessageLengthPosition = kSeqNoPosition
-		+ kSeqNoInts;
-	static constexpr auto kMessageLengthInts = 1;
-	static constexpr auto kMessageBodyPosition = kMessageLengthPosition
-		+ kMessageLengthInts;
-
-	static SecureRequest Prepare(uint32 size, uint32 reserveSize = 0);
-
-	template <
-		typename Request,
-		typename = std::enable_if_t<tl::is_boxed_v<Request>>>
-	static SecureRequest Serialize(const Request &request);
-
-	// For template MTP requests and MTPBoxed instanciation.
-	template <typename Accumulator>
-	void write(Accumulator &to) const {
-		if (const auto size = sizeInBytes()) {
-			tl::Writer<Accumulator>::PutBytes(to, dataInBytes(), size);
-		}
-	}
-
-	SecureRequestData *operator->() const;
-	SecureRequestData &operator*() const;
-	explicit operator bool() const;
-
-	void setMsgId(mtpMsgId msgId);
-	[[nodiscard]] mtpMsgId getMsgId() const;
-
-	void setSeqNo(uint32 seqNo);
-	[[nodiscard]] uint32 getSeqNo() const;
-
-	void addPadding(bool extended, bool old);
-	[[nodiscard]] uint32 messageSize() const;
-
-	// "request-like" wrap for msgIds vector
-	[[nodiscard]] bool isSentContainer() const;
-	[[nodiscard]] bool isStateRequest() const;
-	[[nodiscard]] bool needAck() const;
-
-	using ResponseType = void; // don't know real response type =(
-
-private:
-	explicit SecureRequest(const details::SecureRequestCreateTag &);
-
-	[[nodiscard]] size_t sizeInBytes() const;
-	[[nodiscard]] const void *dataInBytes() const;
-
-	std::shared_ptr<SecureRequestData> _data;
-
-};
-
-class SecureRequestData : public mtpBuffer {
-public:
-	explicit SecureRequestData(const details::SecureRequestCreateTag &) {
-	}
-
-	// in toSend: = 0 - must send in container, > 0 - can send without container
-	// in haveSent: = 0 - container with msgIds, > 0 - when was sent
-	int64 msDate = 0;
-
-	mtpRequestId requestId = 0;
-	SecureRequest after;
-	bool needsLayer = false;
-
-};
-
-template <typename Request, typename>
-SecureRequest SecureRequest::Serialize(const Request &request) {
-	const auto requestSize = tl::count_length(request) >> 2;
-	auto serialized = Prepare(requestSize);
-	request.template write<mtpBuffer>(*serialized);
-	return serialized;
-}
-
-} // namespace MTP
-
 using MTPint = tl::int_type;
 
 inline MTPint MTP_int(int32 v) {
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.cpp b/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.cpp
index ae68422b5..c84a40bbd 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.cpp
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.cpp
@@ -7,6 +7,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "mtproto/details/mtproto_bound_key_creator.h"
 
+#include "mtproto/details/mtproto_serialized_request.h"
+
 namespace MTP::details {
 
 BoundKeyCreator::BoundKeyCreator(DcKeyRequest request, Delegate delegate)
@@ -54,7 +56,7 @@ bool BoundKeyCreator::readyToBind() const {
 	return _binder.has_value();
 }
 
-SecureRequest BoundKeyCreator::prepareBindRequest(
+SerializedRequest BoundKeyCreator::prepareBindRequest(
 		const AuthKeyPtr &temporaryKey,
 		uint64 sessionId) {
 	Expects(_binder.has_value());
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.h b/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.h
index e8a7bf100..a1ca4cb83 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.h
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_bound_key_creator.h
@@ -12,6 +12,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 namespace MTP::details {
 
+class SerializedRequest;
+
 class BoundKeyCreator final {
 public:
 	struct Delegate {
@@ -32,7 +34,7 @@ public:
 	void bind(AuthKeyPtr &&persistentKey);
 	void restartBinder();
 	[[nodiscard]] bool readyToBind() const;
-	[[nodiscard]] SecureRequest prepareBindRequest(
+	[[nodiscard]] SerializedRequest prepareBindRequest(
 		const AuthKeyPtr &temporaryKey,
 		uint64 sessionId);
 	[[nodiscard]] DcKeyBindState handleBindResponse(
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.cpp b/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.cpp
index 736a6f4fa..0f6b0b56c 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.cpp
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.cpp
@@ -7,6 +7,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "mtproto/details/mtproto_dc_key_binder.h"
 
+#include "mtproto/details/mtproto_serialized_request.h"
 #include "mtproto/mtp_instance.h"
 #include "base/unixtime.h"
 #include "base/openssl_help.h"
@@ -21,12 +22,12 @@ namespace {
 		const AuthKeyPtr &persistentKey,
 		mtpMsgId realMsgId,
 		const MTPBindAuthKeyInner &data) {
-	auto serialized = SecureRequest::Serialize(data);
+	auto serialized = SerializedRequest::Serialize(data);
 	serialized.setMsgId(realMsgId);
 	serialized.setSeqNo(0);
 	serialized.addPadding(false, true);
 
-	constexpr auto kMsgIdPosition = SecureRequest::kMessageIdPosition;
+	constexpr auto kMsgIdPosition = SerializedRequest::kMessageIdPosition;
 	constexpr auto kMinMessageSize = 5;
 
 	const auto sizeInPrimes = serialized->size();
@@ -77,7 +78,7 @@ DcKeyBinder::DcKeyBinder(AuthKeyPtr &&persistentKey)
 	Expects(_persistentKey != nullptr);
 }
 
-SecureRequest DcKeyBinder::prepareRequest(
+SerializedRequest DcKeyBinder::prepareRequest(
 		const AuthKeyPtr &temporaryKey,
 		uint64 sessionId) {
 	Expects(temporaryKey != nullptr);
@@ -85,7 +86,7 @@ SecureRequest DcKeyBinder::prepareRequest(
 
 	const auto nonce = openssl::RandomValue<uint64>();
 	const auto msgId = base::unixtime::mtproto_msg_id();
-	auto result = SecureRequest::Serialize(MTPauth_BindTempAuthKey(
+	auto result = SerializedRequest::Serialize(MTPauth_BindTempAuthKey(
 		MTP_long(_persistentKey->keyId()),
 		MTP_long(nonce),
 		MTP_int(temporaryKey->expiresAt()),
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.h b/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.h
index ba18176e4..882e0f88d 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.h
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_dc_key_binder.h
@@ -16,6 +16,8 @@ class Instance;
 
 namespace MTP::details {
 
+class SerializedRequest;
+
 enum class DcKeyBindState {
 	Success,
 	Failed,
@@ -26,7 +28,7 @@ class DcKeyBinder final {
 public:
 	explicit DcKeyBinder(AuthKeyPtr &&persistentKey);
 
-	[[nodiscard]] SecureRequest prepareRequest(
+	[[nodiscard]] SerializedRequest prepareRequest(
 		const AuthKeyPtr &temporaryKey,
 		uint64 sessionId);
 	[[nodiscard]] DcKeyBindState handleResponse(const mtpBuffer &response);
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_dump_to_text.h b/Telegram/SourceFiles/mtproto/details/mtproto_dump_to_text.h
index f24361655..61c47665e 100644
--- a/Telegram/SourceFiles/mtproto/details/mtproto_dump_to_text.h
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_dump_to_text.h
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 #include "mtproto/core_types.h"
+#include "mtproto/details/mtproto_serialized_request.h"
 
 namespace MTP::details {
 
diff --git a/Telegram/SourceFiles/mtproto/core_types.cpp b/Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.cpp
similarity index 55%
rename from Telegram/SourceFiles/mtproto/core_types.cpp
rename to Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.cpp
index 50e62f95e..032957d40 100644
--- a/Telegram/SourceFiles/mtproto/core_types.cpp
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.cpp
@@ -5,9 +5,11 @@ the official desktop application for the Telegram messaging service.
 For license and copyright information please follow this link:
 https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
-#include "mtproto/core_types.h"
+#include "mtproto/details/mtproto_serialized_request.h"
 
-namespace MTP {
+#include "base/openssl_help.h"
+
+namespace MTP::details {
 namespace {
 
 uint32 CountPaddingPrimesCount(uint32 requestSize, bool extended, bool old) {
@@ -27,7 +29,7 @@ uint32 CountPaddingPrimesCount(uint32 requestSize, bool extended, bool old) {
 
 	if (extended) {
 		// Some more random padding.
-		result += ((rand_value<uchar>() & 0x0F) << 2);
+		result += ((openssl::RandomValue<uchar>() & 0x0F) << 2);
 	}
 
 	return result;
@@ -35,67 +37,72 @@ uint32 CountPaddingPrimesCount(uint32 requestSize, bool extended, bool old) {
 
 } // namespace
 
-SecureRequest::SecureRequest(const details::SecureRequestCreateTag &tag)
-: _data(std::make_shared<SecureRequestData>(tag)) {
+SerializedRequest::SerializedRequest(const RequestConstructHider::Tag &tag)
+: _data(std::make_shared<RequestData>(tag)) {
 }
 
-SecureRequest SecureRequest::Prepare(uint32 size, uint32 reserveSize) {
+SerializedRequest SerializedRequest::Prepare(
+		uint32 size,
+		uint32 reserveSize) {
+	Expects(size > 0);
+
 	const auto finalSize = std::max(size, reserveSize);
 
-	auto result = SecureRequest(details::SecureRequestCreateTag{});
+	auto result = SerializedRequest(RequestConstructHider::Tag{});
 	result->reserve(kMessageBodyPosition + finalSize);
 	result->resize(kMessageBodyPosition);
 	result->back() = (size << 2);
-	result->msDate = crl::now(); // > 0 - can send without container
+	result->lastSentTime = crl::now();
 	return result;
 }
 
-SecureRequestData *SecureRequest::operator->() const {
+RequestData *SerializedRequest::operator->() const {
 	Expects(_data != nullptr);
 
 	return _data.get();
 }
 
-SecureRequestData &SecureRequest::operator*() const {
+RequestData &SerializedRequest::operator*() const {
 	Expects(_data != nullptr);
 
 	return *_data;
 }
 
-SecureRequest::operator bool() const {
+SerializedRequest::operator bool() const {
 	return (_data != nullptr);
 }
 
-void SecureRequest::setMsgId(mtpMsgId msgId) {
+void SerializedRequest::setMsgId(mtpMsgId msgId) {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
 	memcpy(_data->data() + kMessageIdPosition, &msgId, sizeof(mtpMsgId));
 }
 
-mtpMsgId SecureRequest::getMsgId() const {
+mtpMsgId SerializedRequest::getMsgId() const {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
 	return *(mtpMsgId*)(_data->constData() + kMessageIdPosition);
 }
 
-void SecureRequest::setSeqNo(uint32 seqNo) {
+void SerializedRequest::setSeqNo(uint32 seqNo) {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
 	(*_data)[kSeqNoPosition] = mtpPrime(seqNo);
 }
 
-uint32 SecureRequest::getSeqNo() const {
+uint32 SerializedRequest::getSeqNo() const {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
 	return uint32((*_data)[kSeqNoPosition]);
 }
 
-void SecureRequest::addPadding(bool extended, bool old) {
+void SerializedRequest::addPadding(bool extended, bool old) {
 	Expects(_data != nullptr);
-
-	if (_data->size() <= kMessageBodyPosition) {
-		return;
-	}
+	Expects(_data->size() > kMessageBodyPosition);
 
 	const auto requestSize = (tl::count_length(*this) >> 2);
 	const auto padding = CountPaddingPrimesCount(requestSize, extended, old);
@@ -103,48 +110,38 @@ void SecureRequest::addPadding(bool extended, bool old) {
 	if (uint32(_data->size()) != fullSize) {
 		_data->resize(fullSize);
 		if (padding > 0) {
-			memset_rand(
-				_data->data() + (fullSize - padding),
-				padding * sizeof(mtpPrime));
+			bytes::set_random(bytes::make_span(*_data).subspan(
+				(fullSize - padding) * sizeof(mtpPrime)));
 		}
 	}
 }
 
-uint32 SecureRequest::messageSize() const {
+uint32 SerializedRequest::messageSize() const {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
-	if (_data->size() <= kMessageBodyPosition) {
-		return 0;
-	}
 	const auto ints = (tl::count_length(*this) >> 2);
 	return kMessageIdInts + kSeqNoInts + kMessageLengthInts + ints;
 }
 
-bool SecureRequest::isSentContainer() const {
+bool SerializedRequest::isSentContainer() const {
 	Expects(_data != nullptr);
 
-	if (_data->size() <= kMessageBodyPosition) {
-		return false;
-	}
-	return (!_data->msDate && !getSeqNo()); // msDate = 0, seqNo = 0
+	return _data->isContainerIdsWrap;
 }
 
-bool SecureRequest::isStateRequest() const {
+bool SerializedRequest::isStateRequest() const {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
-	if (_data->size() <= kMessageBodyPosition) {
-		return false;
-	}
 	const auto type = mtpTypeId((*_data)[kMessageBodyPosition]);
 	return (type == mtpc_msgs_state_req);
 }
 
-bool SecureRequest::needAck() const {
+bool SerializedRequest::needAck() const {
 	Expects(_data != nullptr);
+	Expects(_data->size() > kMessageBodyPosition);
 
-	if (_data->size() <= kMessageBodyPosition) {
-		return false;
-	}
 	const auto type = mtpTypeId((*_data)[kMessageBodyPosition]);
 	switch (type) {
 	case mtpc_msg_container:
@@ -160,16 +157,14 @@ bool SecureRequest::needAck() const {
 	return true;
 }
 
-size_t SecureRequest::sizeInBytes() const {
-	return (_data && _data->size() > kMessageBodyPosition)
-		? (*_data)[kMessageLengthPosition]
-		: 0;
+size_t SerializedRequest::sizeInBytes() const {
+	Expects(!_data || _data->size() > kMessageBodyPosition);
+	return _data ? (*_data)[kMessageLengthPosition] : 0;
 }
 
-const void *SecureRequest::dataInBytes() const {
-	return (_data && _data->size() > kMessageBodyPosition)
-		? (_data->constData() + kMessageBodyPosition)
-		: nullptr;
+const void *SerializedRequest::dataInBytes() const {
+	Expects(!_data || _data->size() > kMessageBodyPosition);
+	return _data ? (_data->constData() + kMessageBodyPosition) : nullptr;
 }
 
 } // namespace MTP
diff --git a/Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.h b/Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.h
new file mode 100644
index 000000000..08e13380e
--- /dev/null
+++ b/Telegram/SourceFiles/mtproto/details/mtproto_serialized_request.h
@@ -0,0 +1,109 @@
+/*
+This file is part of Telegram Desktop,
+the official desktop application for the Telegram messaging service.
+
+For license and copyright information please follow this link:
+https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
+*/
+#pragma once
+
+#include "mtproto/core_types.h"
+
+#include <crl/crl_time.h>
+
+namespace MTP::details {
+
+class RequestData;
+class SerializedRequest;
+
+class RequestConstructHider {
+	struct Tag {};
+	friend class RequestData;
+	friend class SerializedRequest;
+};
+
+class SerializedRequest {
+public:
+	SerializedRequest() = default;
+
+	static constexpr auto kSaltInts = 2;
+	static constexpr auto kSessionIdInts = 2;
+	static constexpr auto kMessageIdPosition = kSaltInts + kSessionIdInts;
+	static constexpr auto kMessageIdInts = 2;
+	static constexpr auto kSeqNoPosition = kMessageIdPosition
+		+ kMessageIdInts;
+	static constexpr auto kSeqNoInts = 1;
+	static constexpr auto kMessageLengthPosition = kSeqNoPosition
+		+ kSeqNoInts;
+	static constexpr auto kMessageLengthInts = 1;
+	static constexpr auto kMessageBodyPosition = kMessageLengthPosition
+		+ kMessageLengthInts;
+
+	static SerializedRequest Prepare(uint32 size, uint32 reserveSize = 0);
+
+	template <
+		typename Request,
+		typename = std::enable_if_t<tl::is_boxed_v<Request>>>
+	static SerializedRequest Serialize(const Request &request);
+
+	// For template MTP requests and MTPBoxed instantiation.
+	template <typename Accumulator>
+	void write(Accumulator &to) const {
+		if (const auto size = sizeInBytes()) {
+			tl::Writer<Accumulator>::PutBytes(to, dataInBytes(), size);
+		}
+	}
+
+	RequestData *operator->() const;
+	RequestData &operator*() const;
+	explicit operator bool() const;
+
+	void setMsgId(mtpMsgId msgId);
+	[[nodiscard]] mtpMsgId getMsgId() const;
+
+	void setSeqNo(uint32 seqNo);
+	[[nodiscard]] uint32 getSeqNo() const;
+
+	void addPadding(bool extended, bool old);
+	[[nodiscard]] uint32 messageSize() const;
+
+	// "request-like" wrap for msgIds vector
+	[[nodiscard]] bool isSentContainer() const;
+	[[nodiscard]] bool isStateRequest() const;
+	[[nodiscard]] bool needAck() const;
+
+	using ResponseType = void; // don't know real response type =(
+
+private:
+	explicit SerializedRequest(const RequestConstructHider::Tag &);
+
+	[[nodiscard]] size_t sizeInBytes() const;
+	[[nodiscard]] const void *dataInBytes() const;
+
+	std::shared_ptr<RequestData> _data;
+
+};
+
+class RequestData : public mtpBuffer {
+public:
+	explicit RequestData(const RequestConstructHider::Tag &) {
+	}
+
+	SerializedRequest after;
+	crl::time lastSentTime = 0;
+	mtpRequestId requestId = 0;
+	bool needsLayer = false;
+	bool forceSendInContainer = false;
+	bool isContainerIdsWrap = false;
+
+};
+
+template <typename Request, typename>
+SerializedRequest SerializedRequest::Serialize(const Request &request) {
+	const auto requestSize = tl::count_length(request) >> 2;
+	auto serialized = Prepare(requestSize);
+	request.template write<mtpBuffer>(*serialized);
+	return serialized;
+}
+
+} // namespace MTP::details
diff --git a/Telegram/SourceFiles/mtproto/mtp_instance.cpp b/Telegram/SourceFiles/mtproto/mtp_instance.cpp
index 20fa3e1a5..888728b9d 100644
--- a/Telegram/SourceFiles/mtproto/mtp_instance.cpp
+++ b/Telegram/SourceFiles/mtproto/mtp_instance.cpp
@@ -36,6 +36,7 @@ constexpr auto kConfigBecomesOldForBlockedIn = 8 * crl::time(1000);
 constexpr auto kCheckKeyEach = 60 * crl::time(1000);
 
 using namespace internal;
+using namespace details;
 
 std::atomic<int> GlobalAtomicRequestId = 0;
 
@@ -111,7 +112,7 @@ public:
 
 	void sendRequest(
 		mtpRequestId requestId,
-		SecureRequest &&request,
+		SerializedRequest &&request,
 		RPCResponseHandler &&callbacks,
 		ShiftedDcId shiftedDcId,
 		crl::time msCanWait,
@@ -121,9 +122,9 @@ public:
 	void unregisterRequest(mtpRequestId requestId);
 	void storeRequest(
 		mtpRequestId requestId,
-		const SecureRequest &request,
+		const SerializedRequest &request,
 		RPCResponseHandler &&callbacks);
-	SecureRequest getRequest(mtpRequestId requestId);
+	SerializedRequest getRequest(mtpRequestId requestId);
 	void clearCallbacksDelayed(std::vector<RPCCallbackClear> &&ids);
 	void execCallback(mtpRequestId requestId, const mtpPrime *from, const mtpPrime *end);
 	bool hasCallbacks(mtpRequestId requestId);
@@ -238,7 +239,7 @@ private:
 	std::map<mtpRequestId, RPCResponseHandler> _parserMap;
 	QMutex _parserMapLock;
 
-	std::map<mtpRequestId, SecureRequest> _requestMap;
+	std::map<mtpRequestId, SerializedRequest> _requestMap;
 	QReadWriteLock _requestMapLock;
 
 	std::deque<std::pair<mtpRequestId, crl::time>> _delayedRequests;
@@ -911,7 +912,7 @@ void Instance::Private::checkDelayedRequests() {
 			continue;
 		}
 
-		auto request = SecureRequest();
+		auto request = SerializedRequest();
 		{
 			QReadLocker locker(&_requestMapLock);
 			auto it = _requestMap.find(requestId);
@@ -932,7 +933,7 @@ void Instance::Private::checkDelayedRequests() {
 
 void Instance::Private::sendRequest(
 		mtpRequestId requestId,
-		SecureRequest &&request,
+		SerializedRequest &&request,
 		RPCResponseHandler &&callbacks,
 		ShiftedDcId shiftedDcId,
 		crl::time msCanWait,
@@ -951,7 +952,7 @@ void Instance::Private::sendRequest(
 	if (afterRequestId) {
 		request->after = getRequest(afterRequestId);
 	}
-	request->msDate = crl::now(); // > 0 - can send without container
+	request->lastSentTime = crl::now();
 	request->needsLayer = needsLayer;
 
 	session->sendPrepared(request, msCanWait);
@@ -980,7 +981,7 @@ void Instance::Private::unregisterRequest(mtpRequestId requestId) {
 
 void Instance::Private::storeRequest(
 		mtpRequestId requestId,
-		const SecureRequest &request,
+		const SerializedRequest &request,
 		RPCResponseHandler &&callbacks) {
 	if (callbacks.onDone || callbacks.onFail) {
 		QMutexLocker locker(&_parserMapLock);
@@ -992,8 +993,8 @@ void Instance::Private::storeRequest(
 	}
 }
 
-SecureRequest Instance::Private::getRequest(mtpRequestId requestId) {
-	auto result = SecureRequest();
+SerializedRequest Instance::Private::getRequest(mtpRequestId requestId) {
+	auto result = SerializedRequest();
 	{
 		QReadLocker locker(&_requestMapLock);
 		auto it = _requestMap.find(requestId);
@@ -1319,7 +1320,7 @@ bool Instance::Private::onErrorDefault(mtpRequestId requestId, const RPCError &e
 			newdcWithShift = ShiftDcId(newdcWithShift, GetDcIdShift(dcWithShift));
 		}
 
-		auto request = SecureRequest();
+		auto request = SerializedRequest();
 		{
 			QReadLocker locker(&_requestMapLock);
 			auto it = _requestMap.find(requestId);
@@ -1391,7 +1392,7 @@ bool Instance::Private::onErrorDefault(mtpRequestId requestId, const RPCError &e
 		if (badGuestDc) _badGuestDcRequests.insert(requestId);
 		return true;
 	} else if (err == qstr("CONNECTION_NOT_INITED") || err == qstr("CONNECTION_LAYER_INVALID")) {
-		SecureRequest request;
+		SerializedRequest request;
 		{
 			QReadLocker locker(&_requestMapLock);
 			auto it = _requestMap.find(requestId);
@@ -1416,7 +1417,7 @@ bool Instance::Private::onErrorDefault(mtpRequestId requestId, const RPCError &e
 	} else if (err == qstr("CONNECTION_LANG_CODE_INVALID")) {
 		Lang::CurrentCloudManager().resetToDefault();
 	} else if (err == qstr("MSG_WAIT_FAILED")) {
-		SecureRequest request;
+		SerializedRequest request;
 		{
 			QReadLocker locker(&_requestMapLock);
 			auto it = _requestMap.find(requestId);
@@ -1435,7 +1436,7 @@ bool Instance::Private::onErrorDefault(mtpRequestId requestId, const RPCError &e
 			if (const auto afterDcId = queryRequestByDc(request->after->requestId)) {
 				dcWithShift = *shiftedDcId;
 				if (*shiftedDcId != *afterDcId) {
-					request->after = SecureRequest();
+					request->after = SerializedRequest();
 				}
 			} else {
 				LOG(("MTP Error: could not find dependent request %1 by dc").arg(request->after->requestId));
@@ -1852,7 +1853,7 @@ void Instance::keyDestroyedOnServer(ShiftedDcId shiftedDcId, uint64 keyId) {
 
 void Instance::sendRequest(
 		mtpRequestId requestId,
-		SecureRequest &&request,
+		SerializedRequest &&request,
 		RPCResponseHandler &&callbacks,
 		ShiftedDcId shiftedDcId,
 		crl::time msCanWait,
diff --git a/Telegram/SourceFiles/mtproto/mtp_instance.h b/Telegram/SourceFiles/mtproto/mtp_instance.h
index a59a96a9b..17e2f5889 100644
--- a/Telegram/SourceFiles/mtproto/mtp_instance.h
+++ b/Telegram/SourceFiles/mtproto/mtp_instance.h
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 #include "mtproto/mtproto_rpc_sender.h"
+#include "mtproto/details/mtproto_serialized_request.h"
 
 namespace MTP {
 namespace internal {
@@ -139,7 +140,7 @@ public:
 		const auto requestId = internal::GetNextRequestId();
 		sendSerialized(
 			requestId,
-			SecureRequest::Serialize(request),
+			details::SerializedRequest::Serialize(request),
 			std::move(callbacks),
 			shiftedDcId,
 			msCanWait,
@@ -170,7 +171,7 @@ public:
 		const auto requestId = internal::GetNextRequestId();
 		sendRequest(
 			requestId,
-			SecureRequest::Serialize(request),
+			details::SerializedRequest::Serialize(request),
 			{},
 			shiftedDcId,
 			0,
@@ -181,7 +182,7 @@ public:
 
 	void sendSerialized(
 			mtpRequestId requestId,
-			SecureRequest &&request,
+			details::SerializedRequest &&request,
 			RPCResponseHandler &&callbacks,
 			ShiftedDcId shiftedDcId,
 			crl::time msCanWait,
@@ -209,7 +210,7 @@ signals:
 private:
 	void sendRequest(
 		mtpRequestId requestId,
-		SecureRequest &&request,
+		details::SerializedRequest &&request,
 		RPCResponseHandler &&callbacks,
 		ShiftedDcId shiftedDcId,
 		crl::time msCanWait,
diff --git a/Telegram/SourceFiles/mtproto/session.cpp b/Telegram/SourceFiles/mtproto/session.cpp
index ba2ce7fd4..66cf7f31e 100644
--- a/Telegram/SourceFiles/mtproto/session.cpp
+++ b/Telegram/SourceFiles/mtproto/session.cpp
@@ -94,12 +94,6 @@ void SessionData::queueSendAnything(crl::time msCanWait) {
 	});
 }
 
-void SessionData::queueSendMsgsStateInfo(quint64 msgId, QByteArray data) {
-	withSession([=](not_null<Session*> session) {
-		session->sendMsgsStateInfo(msgId, data);
-	});
-}
-
 bool SessionData::connectionInited() const {
 	QMutexLocker lock(&_ownerMutex);
 	return _owner ? _owner->connectionInited() : false;
@@ -300,18 +294,6 @@ void Session::needToResumeAndSend() {
 	}
 }
 
-void Session::sendMsgsStateInfo(quint64 msgId, QByteArray data) {
-	auto info = bytes::vector();
-	if (!data.isEmpty()) {
-		info.resize(data.size());
-		bytes::copy(info, bytes::make_span(data));
-	}
-	_instance->sendProtocolMessage(
-		_shiftedDcId,
-		MTPMsgsStateInfo(
-			MTP_msgs_state_info(MTP_long(msgId), MTP_bytes(data))));
-}
-
 void Session::connectionStateChange(int newState) {
 	_instance->onStateChange(_shiftedDcId, newState);
 }
@@ -356,17 +338,14 @@ int32 Session::requestState(mtpRequestId requestId) const {
 	}
 	if (!connected) {
 		return result;
-	}
-	if (!requestId) return MTP::RequestSent;
-
-	QWriteLocker locker(_data->toSendMutex());
-	const auto &toSend = _data->toSendMap();
-	const auto i = toSend.constFind(requestId);
-	if (i != toSend.cend()) {
-		return MTP::RequestSending;
-	} else {
+	} else if (!requestId) {
 		return MTP::RequestSent;
 	}
+
+	QWriteLocker locker(_data->toSendMutex());
+	return _data->toSendMap().contains(requestId)
+		? MTP::RequestSending
+		: MTP::RequestSent;
 }
 
 int32 Session::getState() const {
@@ -397,13 +376,13 @@ QString Session::transport() const {
 }
 
 void Session::sendPrepared(
-		const SecureRequest &request,
+		const details::SerializedRequest &request,
 		crl::time msCanWait) {
 	DEBUG_LOG(("MTP Info: adding request to toSendMap, msCanWait %1"
 		).arg(msCanWait));
 	{
 		QWriteLocker locker(_data->toSendMutex());
-		_data->toSendMap().insert(request->requestId, request);
+		_data->toSendMap().emplace(request->requestId, request);
 		*(mtpMsgId*)(request->data() + 4) = 0;
 		*(request->data() + 6) = 0;
 	}
@@ -510,35 +489,27 @@ void Session::tryToReceive() {
 		return;
 	}
 	while (true) {
-		auto requestId = mtpRequestId(0);
-		auto isUpdate = false;
-		auto message = SerializedMessage();
-		{
-			QWriteLocker locker(_data->haveReceivedMutex());
-			auto &responses = _data->haveReceivedResponses();
-			auto response = responses.begin();
-			if (response == responses.cend()) {
-				auto &updates = _data->haveReceivedUpdates();
-				auto update = updates.begin();
-				if (update == updates.cend()) {
-					return;
-				} else {
-					message = std::move(*update);
-					isUpdate = true;
-					updates.pop_front();
-				}
-			} else {
-				requestId = response.key();
-				message = std::move(response.value());
-				responses.erase(response);
-			}
+		auto lock = QWriteLocker(_data->haveReceivedMutex());
+		const auto responses = base::take(_data->haveReceivedResponses());
+		const auto updates = base::take(_data->haveReceivedUpdates());
+		lock.unlock();
+		if (responses.empty() && updates.empty()) {
+			break;
 		}
-		if (isUpdate) {
-			if (_shiftedDcId == BareDcId(_shiftedDcId)) { // call globalCallback only in main session
-				_instance->globalCallback(message.constData(), message.constData() + message.size());
+		for (const auto &[requestId, response] : responses) {
+			_instance->execCallback(
+				requestId,
+				response.constData(),
+				response.constData() + response.size());
+		}
+
+		// Call globalCallback only in main session.
+		if (_shiftedDcId == BareDcId(_shiftedDcId)) {
+			for (const auto &update : updates) {
+				_instance->globalCallback(
+					update.constData(),
+					update.constData() + update.size());
 			}
-		} else {
-			_instance->execCallback(requestId, message.constData(), message.constData() + message.size());
 		}
 	}
 }
diff --git a/Telegram/SourceFiles/mtproto/session.h b/Telegram/SourceFiles/mtproto/session.h
index 896dafe4b..ce4ef83a3 100644
--- a/Telegram/SourceFiles/mtproto/session.h
+++ b/Telegram/SourceFiles/mtproto/session.h
@@ -10,6 +10,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "base/timer.h"
 #include "mtproto/mtproto_rpc_sender.h"
 #include "mtproto/mtproto_proxy_data.h"
+#include "mtproto/details/mtproto_serialized_request.h"
 
 #include <QtCore/QTimer>
 
@@ -27,18 +28,6 @@ class Connection;
 enum class TemporaryKeyType;
 enum class CreatingKeyType;
 
-using PreRequestMap = QMap<mtpRequestId, SecureRequest>;
-using RequestMap = QMap<mtpMsgId, SecureRequest>;
-using SerializedMessage = mtpBuffer;
-
-inline bool ResponseNeedsAck(const SerializedMessage &response) {
-	if (response.size() < 8) {
-		return false;
-	}
-	auto seqNo = *(uint32*)(response.constData() + 6);
-	return (seqNo & 0x01) ? true : false;
-}
-
 struct ConnectionOptions {
 	ConnectionOptions() = default;
 	ConnectionOptions(
@@ -80,38 +69,26 @@ public:
 		return _options;
 	}
 
-	not_null<QReadWriteLock*> toSendMutex() const {
+	not_null<QReadWriteLock*> toSendMutex() {
 		return &_toSendLock;
 	}
-	not_null<QReadWriteLock*> haveSentMutex() const {
+	not_null<QReadWriteLock*> haveSentMutex() {
 		return &_haveSentLock;
 	}
-	not_null<QReadWriteLock*> haveReceivedMutex() const {
+	not_null<QReadWriteLock*> haveReceivedMutex() {
 		return &_haveReceivedLock;
 	}
 
-	PreRequestMap &toSendMap() {
+	base::flat_map<mtpRequestId, details::SerializedRequest> &toSendMap() {
 		return _toSend;
 	}
-	const PreRequestMap &toSendMap() const {
-		return _toSend;
-	}
-	RequestMap &haveSentMap() {
+	base::flat_map<mtpMsgId, details::SerializedRequest> &haveSentMap() {
 		return _haveSent;
 	}
-	const RequestMap &haveSentMap() const {
-		return _haveSent;
-	}
-	QMap<mtpRequestId, SerializedMessage> &haveReceivedResponses() {
+	base::flat_map<mtpRequestId, mtpBuffer> &haveReceivedResponses() {
 		return _receivedResponses;
 	}
-	const QMap<mtpRequestId, SerializedMessage> &haveReceivedResponses() const {
-		return _receivedResponses;
-	}
-	QList<SerializedMessage> &haveReceivedUpdates() {
-		return _receivedUpdates;
-	}
-	const QList<SerializedMessage> &haveReceivedUpdates() const {
+	std::vector<mtpBuffer> &haveReceivedUpdates() {
 		return _receivedUpdates;
 	}
 
@@ -126,7 +103,6 @@ public:
 	void queueConnectionStateChange(int newState);
 	void queueResetDone();
 	void queueSendAnything(crl::time msCanWait = 0);
-	void queueSendMsgsStateInfo(quint64 msgId, QByteArray data);
 
 	[[nodiscard]] bool connectionInited() const;
 	[[nodiscard]] AuthKeyPtr getPersistentKey() const;
@@ -148,18 +124,17 @@ private:
 	mutable QMutex _ownerMutex;
 
 	ConnectionOptions _options;
-
-	PreRequestMap _toSend; // map of request_id -> request, that is waiting to be sent
-	RequestMap _haveSent; // map of msg_id -> request, that was sent, msDate = 0 for msgs_state_req (no resend / state req), msDate = 0, seqNo = 0 for containers
-
-	QMap<mtpRequestId, SerializedMessage> _receivedResponses; // map of request_id -> response that should be processed in the main thread
-	QList<SerializedMessage> _receivedUpdates; // list of updates that should be processed in the main thread
-
-	// mutexes
 	mutable QReadWriteLock _optionsLock;
-	mutable QReadWriteLock _toSendLock;
-	mutable QReadWriteLock _haveSentLock;
-	mutable QReadWriteLock _haveReceivedLock;
+
+	base::flat_map<mtpRequestId, details::SerializedRequest> _toSend; // map of request_id -> request, that is waiting to be sent
+	QReadWriteLock _toSendLock;
+
+	base::flat_map<mtpMsgId, details::SerializedRequest> _haveSent; // map of msg_id -> request, that was sent
+	QReadWriteLock _haveSentLock;
+
+	base::flat_map<mtpRequestId, mtpBuffer> _receivedResponses; // map of request_id -> response that should be processed in the main thread
+	std::vector<mtpBuffer> _receivedUpdates; // list of updates that should be processed in the main thread
+	QReadWriteLock _haveReceivedLock;
 
 };
 
@@ -189,7 +164,9 @@ public:
 	[[nodiscard]] AuthKeyPtr getPersistentKey() const;
 	[[nodiscard]] AuthKeyPtr getTemporaryKey(TemporaryKeyType type) const;
 	[[nodiscard]] bool connectionInited() const;
-	void sendPrepared(const SecureRequest &request, crl::time msCanWait = 0);
+	void sendPrepared(
+		const details::SerializedRequest &request,
+		crl::time msCanWait = 0);
 
 	// Connection thread.
 	[[nodiscard]] CreatingKeyType acquireKeyCreation(TemporaryKeyType type);
@@ -212,7 +189,6 @@ public:
 	void connectionStateChange(int newState);
 	void resetDone();
 	void sendAnything(crl::time msCanWait = 0);
-	void sendMsgsStateInfo(quint64 msgId, QByteArray data);
 
 signals:
 	void authKeyChanged();
diff --git a/Telegram/gyp/lib_mtproto.gyp b/Telegram/gyp/lib_mtproto.gyp
index 4b01766a2..f95b4310d 100644
--- a/Telegram/gyp/lib_mtproto.gyp
+++ b/Telegram/gyp/lib_mtproto.gyp
@@ -44,6 +44,8 @@
       '<(src_loc)/mtproto/details/mtproto_dump_to_text.h',
       '<(src_loc)/mtproto/details/mtproto_received_ids_manager.cpp',
       '<(src_loc)/mtproto/details/mtproto_received_ids_manager.h',
+      '<(src_loc)/mtproto/details/mtproto_serialized_request.cpp',
+      '<(src_loc)/mtproto/details/mtproto_serialized_request.h',
       '<(src_loc)/mtproto/mtproto_abstract_socket.cpp',
       '<(src_loc)/mtproto/mtproto_abstract_socket.h',
       '<(src_loc)/mtproto/mtproto_auth_key.cpp',
diff --git a/Telegram/gyp/telegram/sources.txt b/Telegram/gyp/telegram/sources.txt
index e7ccceed3..0bd944970 100644
--- a/Telegram/gyp/telegram/sources.txt
+++ b/Telegram/gyp/telegram/sources.txt
@@ -547,7 +547,6 @@
 <(src_loc)/mtproto/connection_resolving.h
 <(src_loc)/mtproto/connection_tcp.cpp
 <(src_loc)/mtproto/connection_tcp.h
-<(src_loc)/mtproto/core_types.cpp
 <(src_loc)/mtproto/core_types.h
 <(src_loc)/mtproto/dcenter.cpp
 <(src_loc)/mtproto/dcenter.h
diff --git a/Telegram/lib_tl b/Telegram/lib_tl
index 2bf101114..13918d5b5 160000
--- a/Telegram/lib_tl
+++ b/Telegram/lib_tl
@@ -1 +1 @@
-Subproject commit 2bf101114f0a54c868a2703a9a80c06c0f2d2c41
+Subproject commit 13918d5b5c4611ef1563a13ac1daf4d2c77c5f49