diff --git a/Telegram/SourceFiles/base/openssl_help.h b/Telegram/SourceFiles/base/openssl_help.h
index 9b0be2da1..54f03842d 100644
--- a/Telegram/SourceFiles/base/openssl_help.h
+++ b/Telegram/SourceFiles/base/openssl_help.h
@@ -10,6 +10,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include <openssl/bn.h>
 #include <openssl/sha.h>
 #include <openssl/rand.h>
+#include <openssl/aes.h>
+#include <openssl/crypto.h>
 #include "base/bytes.h"
 
 namespace openssl {
@@ -61,7 +63,7 @@ public:
 	explicit BigNum(unsigned int word) : BigNum() {
 		setWord(word);
 	}
-	explicit BigNum(base::const_byte_span bytes) : BigNum() {
+	explicit BigNum(bytes::const_span bytes) : BigNum() {
 		setBytes(bytes);
 	}
 
@@ -70,7 +72,7 @@ public:
 			_failed = true;
 		}
 	}
-	void setBytes(base::const_byte_span bytes) {
+	void setBytes(bytes::const_span bytes) {
 		if (!BN_bin2bn(
 				reinterpret_cast<const unsigned char*>(bytes.data()),
 				bytes.size(),
@@ -162,12 +164,12 @@ public:
 		return failed() ? 0 : BN_num_bytes(raw());
 	}
 
-	base::byte_vector getBytes() const {
+	bytes::vector getBytes() const {
 		if (failed()) {
-			return base::byte_vector();
+			return {};
 		}
 		auto length = BN_num_bytes(raw());
-		auto result = base::byte_vector(length, gsl::byte());
+		auto result = bytes::vector(length);
 		auto resultSize = BN_bn2bin(
 			raw(),
 			reinterpret_cast<unsigned char*>(result.data()));
@@ -207,44 +209,35 @@ inline BigNum operator-(const BigNum &a, const BigNum &b) {
 	return result;
 }
 
-inline base::byte_array<SHA512_DIGEST_LENGTH> Sha512(
-		base::const_byte_span bytes) {
-	auto result = base::byte_array<SHA512_DIGEST_LENGTH>();
+inline bytes::vector Sha512(bytes::const_span data) {
+	auto result = bytes::vector(SHA512_DIGEST_LENGTH);
 	SHA512(
-		reinterpret_cast<const unsigned char*>(bytes.data()),
-		bytes.size(),
+		reinterpret_cast<const unsigned char*>(data.data()),
+		data.size(),
 		reinterpret_cast<unsigned char*>(result.data()));
 	return result;
 }
 
-inline base::byte_array<SHA256_DIGEST_LENGTH> Sha256(
-		base::const_byte_span bytes) {
-	auto result = base::byte_array<SHA256_DIGEST_LENGTH>();
+inline bytes::vector Sha256(bytes::const_span data) {
+	auto result = bytes::vector(SHA256_DIGEST_LENGTH);
 	SHA256(
-		reinterpret_cast<const unsigned char*>(bytes.data()),
-		bytes.size(),
+		reinterpret_cast<const unsigned char*>(data.data()),
+		data.size(),
 		reinterpret_cast<unsigned char*>(result.data()));
 	return result;
 }
 
-inline base::byte_array<SHA_DIGEST_LENGTH> Sha1(
-		base::const_byte_span bytes) {
-	auto result = base::byte_array<SHA_DIGEST_LENGTH>();
+inline bytes::vector Sha1(bytes::const_span data) {
+	auto result = bytes::vector(SHA_DIGEST_LENGTH);
 	SHA1(
-		reinterpret_cast<const unsigned char*>(bytes.data()),
-		bytes.size(),
+		reinterpret_cast<const unsigned char*>(data.data()),
+		data.size(),
 		reinterpret_cast<unsigned char*>(result.data()));
 	return result;
 }
 
-inline int FillRandom(base::byte_span bytes) {
-	return RAND_bytes(
-		reinterpret_cast<unsigned char*>(bytes.data()),
-		bytes.size());
-}
-
-inline void AddRandomSeed(base::const_byte_span bytes) {
-	RAND_seed(bytes.data(), bytes.size());
+inline void AddRandomSeed(bytes::const_span data) {
+	RAND_seed(data.data(), data.size());
 }
 
 } // namespace openssl
diff --git a/Telegram/SourceFiles/boxes/passcode_box.cpp b/Telegram/SourceFiles/boxes/passcode_box.cpp
index ac6c187b5..bbd8ec3fe 100644
--- a/Telegram/SourceFiles/boxes/passcode_box.cpp
+++ b/Telegram/SourceFiles/boxes/passcode_box.cpp
@@ -7,6 +7,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "boxes/passcode_box.h"
 
+#include "base/bytes.h"
 #include "lang/lang_keys.h"
 #include "boxes/confirm_box.h"
 #include "mainwindow.h"
@@ -329,7 +330,7 @@ void PasscodeBox::save(bool force) {
 			if (_oldPasscode->isHidden() || _newPasscode->isHidden()) {
 				flags |= MTPDaccount_passwordInputSettings::Flag::f_email;
 			}
-			const auto newSecureSecret = base::byte_vector();
+			const auto newSecureSecret = bytes::vector();
 			_setRequest = MTP::send(
 				MTPaccount_UpdatePasswordSettings(
 					MTP_bytes(oldPasswordHash),
diff --git a/Telegram/SourceFiles/calls/calls_call.cpp b/Telegram/SourceFiles/calls/calls_call.cpp
index 635b11ced..109704cb1 100644
--- a/Telegram/SourceFiles/calls/calls_call.cpp
+++ b/Telegram/SourceFiles/calls/calls_call.cpp
@@ -62,8 +62,9 @@ void ConvertEndpoint(
 }
 
 constexpr auto kFingerprintDataSize = 256;
-uint64 ComputeFingerprint(
-		const std::array<gsl::byte, kFingerprintDataSize> &authKey) {
+uint64 ComputeFingerprint(bytes::const_span authKey) {
+	Expects(authKey.size() == kFingerprintDataSize);
+
 	auto hash = openssl::Sha1(authKey);
 	return (gsl::to_integer<uint64>(hash[19]) << 56)
 		| (gsl::to_integer<uint64>(hash[18]) << 48)
@@ -133,7 +134,7 @@ Call::Call(
 	}
 }
 
-void Call::generateModExpFirst(base::const_byte_span randomSeed) {
+void Call::generateModExpFirst(bytes::const_span randomSeed) {
 	auto first = MTP::CreateModExp(_dhConfig.g, _dhConfig.p, randomSeed);
 	if (first.modexp.empty()) {
 		LOG(("Call Error: Could not compute mod-exp first."));
@@ -141,7 +142,7 @@ void Call::generateModExpFirst(base::const_byte_span randomSeed) {
 		return;
 	}
 
-	_randomPower = first.randomPower;
+	_randomPower = std::move(first.randomPower);
 	if (_type == Type::Incoming) {
 		_gb = std::move(first.modexp);
 	} else {
@@ -157,7 +158,7 @@ bool Call::isIncomingWaiting() const {
 	return (_state == State::Starting) || (_state == State::WaitingIncoming);
 }
 
-void Call::start(base::const_byte_span random) {
+void Call::start(bytes::const_span random) {
 	// Save config here, because it is possible that it changes between
 	// different usages inside the same call.
 	_dhConfig = _delegate->getDhConfig();
@@ -312,7 +313,7 @@ void Call::redial() {
 
 QString Call::getDebugLog() const {
 	constexpr auto kDebugLimit = 4096;
-	auto bytes = base::byte_vector(kDebugLimit, gsl::byte {});
+	auto bytes = bytes::vector(kDebugLimit, gsl::byte {});
 	_controller->GetDebugString(reinterpret_cast<char*>(bytes.data()), bytes.size());
 	auto end = std::find(bytes.begin(), bytes.end(), gsl::byte {});
 	auto size = (end - bytes.begin());
@@ -342,12 +343,13 @@ bool Call::isKeyShaForFingerprintReady() const {
 	return (_keyFingerprint != 0);
 }
 
-base::byte_array<Call::kSha256Size> Call::getKeyShaForFingerprint() const {
+bytes::vector Call::getKeyShaForFingerprint() const {
 	Expects(isKeyShaForFingerprintReady());
 	Expects(!_ga.empty());
-	auto encryptedChatAuthKey = base::byte_vector(_authKey.size() + _ga.size(), gsl::byte {});
-	base::copy_bytes(gsl::make_span(encryptedChatAuthKey).subspan(0, _authKey.size()), _authKey);
-	base::copy_bytes(gsl::make_span(encryptedChatAuthKey).subspan(_authKey.size(), _ga.size()), _ga);
+
+	auto encryptedChatAuthKey = bytes::vector(_authKey.size() + _ga.size(), gsl::byte {});
+	bytes::copy(gsl::make_span(encryptedChatAuthKey).subspan(0, _authKey.size()), _authKey);
+	bytes::copy(gsl::make_span(encryptedChatAuthKey).subspan(_authKey.size(), _ga.size()), _ga);
 	return openssl::Sha256(encryptedChatAuthKey);
 }
 
@@ -367,13 +369,13 @@ bool Call::handleUpdate(const MTPPhoneCall &call) {
 		}
 		_id = data.vid.v;
 		_accessHash = data.vaccess_hash.v;
-		auto gaHashBytes = bytesFromMTP(data.vg_a_hash);
+		auto gaHashBytes = bytes::make_span(data.vg_a_hash.v);
 		if (gaHashBytes.size() != _gaHash.size()) {
 			LOG(("Call Error: Wrong g_a_hash size %1, expected %2.").arg(gaHashBytes.size()).arg(_gaHash.size()));
 			finish(FinishType::Failed);
 			return true;
 		}
-		base::copy_bytes(gsl::make_span(_gaHash), gaHashBytes);
+		bytes::copy(_gaHash, gaHashBytes);
 	} return true;
 
 	case mtpc_phoneCallEmpty: {
@@ -453,7 +455,7 @@ bool Call::handleUpdate(const MTPPhoneCall &call) {
 void Call::confirmAcceptedCall(const MTPDphoneCallAccepted &call) {
 	Expects(_type == Type::Outgoing);
 
-	auto firstBytes = bytesFromMTP(call.vg_b);
+	auto firstBytes = bytes::make_span(call.vg_b.v);
 	auto computedAuthKey = MTP::CreateAuthKey(firstBytes, _randomPower, _dhConfig.p);
 	if (computedAuthKey.empty()) {
 		LOG(("Call Error: Could not compute mod-exp final."));
@@ -493,13 +495,13 @@ void Call::confirmAcceptedCall(const MTPDphoneCallAccepted &call) {
 void Call::startConfirmedCall(const MTPDphoneCall &call) {
 	Expects(_type == Type::Incoming);
 
-	auto firstBytes = bytesFromMTP(call.vg_a_or_b);
+	auto firstBytes = bytes::make_span(call.vg_a_or_b.v);
 	if (_gaHash != openssl::Sha256(firstBytes)) {
 		LOG(("Call Error: Wrong g_a hash received."));
 		finish(FinishType::Failed);
 		return;
 	}
-	_ga = base::byte_vector(firstBytes.begin(), firstBytes.end());
+	_ga = bytes::vector(firstBytes.begin(), firstBytes.end());
 
 	auto computedAuthKey = MTP::CreateAuthKey(firstBytes, _randomPower, _dhConfig.p);
 	if (computedAuthKey.empty()) {
@@ -535,12 +537,12 @@ void Call::createAndStartController(const MTPDphoneCall &call) {
 		auto callLogFolder = cWorkingDir() + qsl("DebugLogs");
 		auto callLogPath = callLogFolder + qsl("/last_call_log.txt");
 		auto callLogNative = QFile::encodeName(QDir::toNativeSeparators(callLogPath));
-		auto callLogBytesSrc = gsl::as_bytes(gsl::make_span(callLogNative));
-		auto callLogBytesDst = gsl::as_writeable_bytes(gsl::make_span(config.logFilePath));
+		auto callLogBytesSrc = bytes::make_span(callLogNative);
+		auto callLogBytesDst = bytes::make_span(config.logFilePath);
 		if (callLogBytesSrc.size() + 1 <= callLogBytesDst.size()) { // +1 - zero-terminator
 			QFile(callLogPath).remove();
 			QDir().mkpath(callLogFolder);
-			base::copy_bytes(callLogBytesDst, callLogBytesSrc);
+			bytes::copy(callLogBytesDst, callLogBytesSrc);
 		}
 	}
 
diff --git a/Telegram/SourceFiles/calls/calls_call.h b/Telegram/SourceFiles/calls/calls_call.h
index ce1f9ffd7..0d28b89fb 100644
--- a/Telegram/SourceFiles/calls/calls_call.h
+++ b/Telegram/SourceFiles/calls/calls_call.h
@@ -9,6 +9,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "base/weak_ptr.h"
 #include "base/timer.h"
+#include "base/bytes.h"
 #include "mtproto/sender.h"
 #include "mtproto/auth_key.h"
 
@@ -27,7 +28,7 @@ namespace Calls {
 struct DhConfig {
 	int32 version = 0;
 	int32 g = 0;
-	std::vector<gsl::byte> p;
+	bytes::vector p;
 };
 
 class Call : public base::has_weak_ptr, private MTP::Sender {
@@ -48,8 +49,6 @@ public:
 
 	};
 
-	static constexpr auto kRandomPowerSize = 256;
-	static constexpr auto kSha256Size = 32;
 	static constexpr auto kSoundSampleMs = 100;
 
 	enum class Type {
@@ -66,7 +65,7 @@ public:
 	}
 	bool isIncomingWaiting() const;
 
-	void start(base::const_byte_span random);
+	void start(bytes::const_span random);
 	bool handleUpdate(const MTPPhoneCall &call);
 
 	enum State {
@@ -116,7 +115,7 @@ public:
 	void redial();
 
 	bool isKeyShaForFingerprintReady() const;
-	std::array<gsl::byte, kSha256Size> getKeyShaForFingerprint() const;
+	bytes::vector getKeyShaForFingerprint() const;
 
 	QString getDebugLog() const;
 
@@ -152,7 +151,7 @@ private:
 	void startIncoming();
 	void startWaitingTrack();
 
-	void generateModExpFirst(base::const_byte_span randomSeed);
+	void generateModExpFirst(bytes::const_span randomSeed);
 	void handleControllerStateChange(
 		tgvoip::VoIPController *controller,
 		int state);
@@ -191,10 +190,10 @@ private:
 	base::Observable<bool> _muteChanged;
 
 	DhConfig _dhConfig;
-	std::vector<gsl::byte> _ga;
-	std::vector<gsl::byte> _gb;
-	std::array<gsl::byte, kSha256Size> _gaHash;
-	std::array<gsl::byte, kRandomPowerSize> _randomPower;
+	bytes::vector _ga;
+	bytes::vector _gb;
+	bytes::vector _gaHash;
+	bytes::vector _randomPower;
 	MTP::AuthKey::Data _authKey;
 	MTPPhoneCallProtocol _protocol;
 
diff --git a/Telegram/SourceFiles/calls/calls_emoji_fingerprint.cpp b/Telegram/SourceFiles/calls/calls_emoji_fingerprint.cpp
index aebf8efb0..91a362ac5 100644
--- a/Telegram/SourceFiles/calls/calls_emoji_fingerprint.cpp
+++ b/Telegram/SourceFiles/calls/calls_emoji_fingerprint.cpp
@@ -99,7 +99,7 @@ const ushort Offsets[] = {
 620, 622, 624, 626, 628, 630, 632, 634, 636, 638, 640, 641,
 642, 643, 644, 646, 648, 650, 652, 654, 656, 658 };
 
-uint64 ComputeEmojiIndex(base::const_byte_span bytes) {
+uint64 ComputeEmojiIndex(bytes::const_span bytes) {
 	Expects(bytes.size() == 8);
 	return ((gsl::to_integer<uint64>(bytes[0]) & 0x7F) << 56)
 		| (gsl::to_integer<uint64>(bytes[1]) << 48)
diff --git a/Telegram/SourceFiles/calls/calls_instance.cpp b/Telegram/SourceFiles/calls/calls_instance.cpp
index 3db61ec88..9ebb92a86 100644
--- a/Telegram/SourceFiles/calls/calls_instance.cpp
+++ b/Telegram/SourceFiles/calls/calls_instance.cpp
@@ -126,26 +126,26 @@ void Instance::refreshDhConfig() {
 	Expects(_currentCall != nullptr);
 	request(MTPmessages_GetDhConfig(
 		MTP_int(_dhConfig.version),
-		MTP_int(Call::kRandomPowerSize)
+		MTP_int(MTP::ModExpFirst::kRandomPowerSize)
 	)).done([this, call = base::make_weak(_currentCall)](
 			const MTPmessages_DhConfig &result) {
-		auto random = base::const_byte_span();
+		auto random = bytes::const_span();
 		switch (result.type()) {
 		case mtpc_messages_dhConfig: {
 			auto &config = result.c_messages_dhConfig();
-			if (!MTP::IsPrimeAndGood(bytesFromMTP(config.vp), config.vg.v)) {
+			if (!MTP::IsPrimeAndGood(bytes::make_span(config.vp.v), config.vg.v)) {
 				LOG(("API Error: bad p/g received in dhConfig."));
 				callFailed(call.get());
 				return;
 			}
 			_dhConfig.g = config.vg.v;
-			_dhConfig.p = byteVectorFromMTP(config.vp);
-			random = bytesFromMTP(config.vrandom);
+			_dhConfig.p = bytes::make_vector(config.vp.v);
+			random = bytes::make_span(config.vrandom.v);
 		} break;
 
 		case mtpc_messages_dhConfigNotModified: {
 			auto &config = result.c_messages_dhConfigNotModified();
-			random = bytesFromMTP(config.vrandom);
+			random = bytes::make_span(config.vrandom.v);
 			if (!_dhConfig.g || _dhConfig.p.empty()) {
 				LOG(("API Error: dhConfigNotModified on zero version."));
 				callFailed(call.get());
@@ -156,7 +156,7 @@ void Instance::refreshDhConfig() {
 		default: Unexpected("Type in messages.getDhConfig");
 		}
 
-		if (random.size() != Call::kRandomPowerSize) {
+		if (random.size() != MTP::ModExpFirst::kRandomPowerSize) {
 			LOG(("API Error: dhConfig random bytes wrong size: %1").arg(random.size()));
 			callFailed(call.get());
 			return;
@@ -186,7 +186,7 @@ void Instance::refreshServerConfig() {
 		_lastServerConfigUpdateTime = getms(true);
 
 		auto configUpdate = std::map<std::string, std::string>();
-		auto bytes = bytesFromMTP(result.c_dataJSON().vdata);
+		auto bytes = bytes::make_span(result.c_dataJSON().vdata.v);
 		auto error = QJsonParseError { 0, QJsonParseError::NoError };
 		auto document = QJsonDocument::fromJson(QByteArray::fromRawData(reinterpret_cast<const char*>(bytes.data()), bytes.size()), &error);
 		if (error.error != QJsonParseError::NoError) {
diff --git a/Telegram/SourceFiles/core/utils.h b/Telegram/SourceFiles/core/utils.h
index 08f6f652a..b4acd5213 100644
--- a/Telegram/SourceFiles/core/utils.h
+++ b/Telegram/SourceFiles/core/utils.h
@@ -92,31 +92,6 @@ using set_of_unique_ptr = std::set<std::unique_ptr<T>, base::pointer_comparator<
 template <typename T>
 using set_of_shared_ptr = std::set<std::shared_ptr<T>, base::pointer_comparator<T>>;
 
-using byte_span = gsl::span<gsl::byte>;
-using const_byte_span = gsl::span<const gsl::byte>;
-using byte_vector = std::vector<gsl::byte>;
-template <size_t N>
-using byte_array = std::array<gsl::byte, N>;
-
-inline void copy_bytes(byte_span destination, const_byte_span source) {
-	Expects(destination.size() >= source.size());
-	memcpy(destination.data(), source.data(), source.size());
-}
-
-inline void move_bytes(byte_span destination, const_byte_span source) {
-	Expects(destination.size() >= source.size());
-	memmove(destination.data(), source.data(), source.size());
-}
-
-inline void set_bytes(byte_span destination, gsl::byte value) {
-	memset(destination.data(), gsl::to_integer<unsigned char>(value), destination.size());
-}
-
-inline int compare_bytes(const_byte_span a, const_byte_span b) {
-	auto aSize = a.size(), bSize = b.size();
-	return (aSize > bSize) ? 1 : (aSize < bSize) ? -1 : memcmp(a.data(), b.data(), aSize);
-}
-
 // Thanks https://stackoverflow.com/a/28139075
 
 template <typename Container>
diff --git a/Telegram/SourceFiles/media/media_audio.cpp b/Telegram/SourceFiles/media/media_audio.cpp
index 38aa7b1e4..d7b2e483f 100644
--- a/Telegram/SourceFiles/media/media_audio.cpp
+++ b/Telegram/SourceFiles/media/media_audio.cpp
@@ -1393,7 +1393,7 @@ void DetachFromDevice() {
 class FFMpegAttributesReader : public AbstractFFMpegLoader {
 public:
 	FFMpegAttributesReader(const FileLocation &file, const QByteArray &data)
-	: AbstractFFMpegLoader(file, data, base::byte_vector()) {
+	: AbstractFFMpegLoader(file, data, bytes::vector()) {
 	}
 
 	bool open(TimeMs positionMs) override {
@@ -1519,7 +1519,7 @@ FileMediaInformation::Song PrepareForSending(const QString &fname, const QByteAr
 
 class FFMpegWaveformCounter : public FFMpegLoader {
 public:
-	FFMpegWaveformCounter(const FileLocation &file, const QByteArray &data) : FFMpegLoader(file, data, base::byte_vector()) {
+	FFMpegWaveformCounter(const FileLocation &file, const QByteArray &data) : FFMpegLoader(file, data, bytes::vector()) {
 	}
 
 	bool open(TimeMs positionMs) override {
@@ -1562,7 +1562,7 @@ public:
 				continue;
 			}
 
-			auto sampleBytes = gsl::as_bytes(gsl::make_span(buffer));
+			auto sampleBytes = bytes::make_span(buffer);
 			if (fmt == AL_FORMAT_MONO8 || fmt == AL_FORMAT_STEREO8) {
 				Media::Audio::IterateSamples<uchar>(sampleBytes, callback);
 			} else if (fmt == AL_FORMAT_MONO16 || fmt == AL_FORMAT_STEREO16) {
diff --git a/Telegram/SourceFiles/media/media_audio.h b/Telegram/SourceFiles/media/media_audio.h
index 23e299117..a0a673eb0 100644
--- a/Telegram/SourceFiles/media/media_audio.h
+++ b/Telegram/SourceFiles/media/media_audio.h
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 #include "storage/localimageloader.h"
+#include "base/bytes.h"
 
 struct VideoSoundData;
 struct VideoSoundPart;
@@ -332,7 +333,7 @@ FORCE_INLINE uint16 ReadOneSample(int16 data) {
 }
 
 template <typename SampleType, typename Callback>
-void IterateSamples(base::const_byte_span bytes, Callback &&callback) {
+void IterateSamples(bytes::const_span bytes, Callback &&callback) {
 	auto samplesPointer = reinterpret_cast<const SampleType*>(bytes.data());
 	auto samplesCount = bytes.size() / sizeof(SampleType);
 	auto samplesData = gsl::make_span(samplesPointer, samplesCount);
diff --git a/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.cpp b/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.cpp
index adff08ace..85b284b20 100644
--- a/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.cpp
+++ b/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.cpp
@@ -7,6 +7,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "media/media_audio_ffmpeg_loader.h"
 
+#include "base/bytes.h"
+
 uint64_t AbstractFFMpegLoader::ComputeChannelLayout(
 		uint64_t channel_layout,
 		int channels) {
@@ -183,8 +185,8 @@ int64_t AbstractFFMpegLoader::_seek_file(void *opaque, int64_t offset, int whenc
 AbstractAudioFFMpegLoader::AbstractAudioFFMpegLoader(
 	const FileLocation &file,
 	const QByteArray &data,
-	base::byte_vector &&bytes)
-: AbstractFFMpegLoader(file, data, std::move(bytes)) {
+	bytes::vector &&buffer)
+: AbstractFFMpegLoader(file, data, std::move(buffer)) {
 	_frame = av_frame_alloc();
 }
 
@@ -490,8 +492,8 @@ AbstractAudioFFMpegLoader::~AbstractAudioFFMpegLoader() {
 FFMpegLoader::FFMpegLoader(
 	const FileLocation &file,
 	const QByteArray &data,
-	base::byte_vector &&bytes)
-: AbstractAudioFFMpegLoader(file, data, std::move(bytes)) {
+	bytes::vector &&buffer)
+: AbstractAudioFFMpegLoader(file, data, std::move(buffer)) {
 }
 
 bool FFMpegLoader::open(TimeMs positionMs) {
diff --git a/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.h b/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.h
index 66f3ad97c..6986642e8 100644
--- a/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.h
+++ b/Telegram/SourceFiles/media/media_audio_ffmpeg_loader.h
@@ -24,8 +24,8 @@ public:
 	AbstractFFMpegLoader(
 		const FileLocation &file,
 		const QByteArray &data,
-		base::byte_vector &&bytes)
-	: AudioPlayerLoader(file, data, std::move(bytes)) {
+		bytes::vector &&buffer)
+	: AudioPlayerLoader(file, data, std::move(buffer)) {
 	}
 
 	bool open(TimeMs positionMs) override;
@@ -73,7 +73,7 @@ public:
 	AbstractAudioFFMpegLoader(
 		const FileLocation &file,
 		const QByteArray &data,
-		base::byte_vector &&bytes);
+		bytes::vector &&buffer);
 
 	int64 samplesCount() override {
 		return _outputSamplesCount;
@@ -141,7 +141,7 @@ public:
 	FFMpegLoader(
 		const FileLocation &file,
 		const QByteArray &data,
-		base::byte_vector &&bytes);
+		bytes::vector &&buffer);
 
 	bool open(TimeMs positionMs) override;
 
diff --git a/Telegram/SourceFiles/media/media_audio_loader.cpp b/Telegram/SourceFiles/media/media_audio_loader.cpp
index b6a329e5f..c98890167 100644
--- a/Telegram/SourceFiles/media/media_audio_loader.cpp
+++ b/Telegram/SourceFiles/media/media_audio_loader.cpp
@@ -7,10 +7,10 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #include "media/media_audio_loader.h"
 
-AudioPlayerLoader::AudioPlayerLoader(const FileLocation &file, const QByteArray &data, base::byte_vector &&bytes)
+AudioPlayerLoader::AudioPlayerLoader(const FileLocation &file, const QByteArray &data, bytes::vector &&buffer)
 : _file(file)
 , _data(data)
-, _bytes(std::move(bytes)) {
+, _bytes(std::move(buffer)) {
 }
 
 AudioPlayerLoader::~AudioPlayerLoader() {
diff --git a/Telegram/SourceFiles/media/media_audio_loader.h b/Telegram/SourceFiles/media/media_audio_loader.h
index c191eebf7..bfc4d04ee 100644
--- a/Telegram/SourceFiles/media/media_audio_loader.h
+++ b/Telegram/SourceFiles/media/media_audio_loader.h
@@ -7,13 +7,18 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
+#include "base/bytes.h"
+
 namespace FFMpeg {
 struct AVPacketDataWrap;
 } // namespace FFMpeg
 
 class AudioPlayerLoader {
 public:
-	AudioPlayerLoader(const FileLocation &file, const QByteArray &data, base::byte_vector &&bytes);
+	AudioPlayerLoader(
+		const FileLocation &file,
+		const QByteArray &data,
+		bytes::vector &&buffer);
 	virtual ~AudioPlayerLoader();
 
 	virtual bool check(const FileLocation &file, const QByteArray &data);
@@ -43,7 +48,7 @@ protected:
 	FileLocation _file;
 	bool _access = false;
 	QByteArray _data;
-	base::byte_vector _bytes;
+	bytes::vector _bytes;
 
 	QFile _f;
 	int _dataPos = 0;
diff --git a/Telegram/SourceFiles/media/media_audio_loaders.cpp b/Telegram/SourceFiles/media/media_audio_loaders.cpp
index 8dc7753d1..7d62955ea 100644
--- a/Telegram/SourceFiles/media/media_audio_loaders.cpp
+++ b/Telegram/SourceFiles/media/media_audio_loaders.cpp
@@ -326,7 +326,7 @@ AudioPlayerLoader *Loaders::setupLoader(
 			}
 			*loader = std::make_unique<ChildFFMpegLoader>(std::move(track->videoData));
 		} else {
-			*loader = std::make_unique<FFMpegLoader>(track->file, track->data, base::byte_vector());
+			*loader = std::make_unique<FFMpegLoader>(track->file, track->data, bytes::vector());
 		}
 		l = loader->get();
 
diff --git a/Telegram/SourceFiles/media/media_audio_track.cpp b/Telegram/SourceFiles/media/media_audio_track.cpp
index 033fca4d1..e31b75c2e 100644
--- a/Telegram/SourceFiles/media/media_audio_track.cpp
+++ b/Telegram/SourceFiles/media/media_audio_track.cpp
@@ -49,7 +49,7 @@ void Track::samplePeakEach(TimeMs peakDuration) {
 	_peakDurationMs = peakDuration;
 }
 
-void Track::fillFromData(base::byte_vector &&data) {
+void Track::fillFromData(bytes::vector &&data) {
 	FFMpegLoader loader(FileLocation(), QByteArray(), std::move(data));
 
 	auto position = qint64(0);
@@ -81,7 +81,7 @@ void Track::fillFromData(base::byte_vector &&data) {
 		auto samplesAdded = int64(0);
 		auto result = loader.readMore(buffer, samplesAdded);
 		if (samplesAdded > 0) {
-			auto sampleBytes = gsl::as_bytes(gsl::make_span(buffer));
+			auto sampleBytes = bytes::make_span(buffer);
 			_samplesCount += samplesAdded;
 			_samples.insert(_samples.end(), sampleBytes.data(), sampleBytes.data() + sampleBytes.size());
 			if (peaksCount) {
@@ -126,7 +126,7 @@ void Track::fillFromFile(const QString &filePath) {
 	if (f.open(QIODevice::ReadOnly)) {
 		auto size = f.size();
 		if (size > 0 && size <= kMaxFileSize) {
-			auto bytes = base::byte_vector(size);
+			auto bytes = bytes::vector(size);
 			if (f.read(reinterpret_cast<char*>(bytes.data()), bytes.size()) == bytes.size()) {
 				fillFromData(std::move(bytes));
 			} else {
diff --git a/Telegram/SourceFiles/media/media_audio_track.h b/Telegram/SourceFiles/media/media_audio_track.h
index 4f7c8da0a..68440c721 100644
--- a/Telegram/SourceFiles/media/media_audio_track.h
+++ b/Telegram/SourceFiles/media/media_audio_track.h
@@ -8,6 +8,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #pragma once
 
 #include "base/timer.h"
+#include "base/bytes.h"
 
 namespace Media {
 namespace Audio {
@@ -20,7 +21,7 @@ public:
 
 	void samplePeakEach(TimeMs peakDuration);
 
-	void fillFromData(base::byte_vector &&data);
+	void fillFromData(bytes::vector &&data);
 	void fillFromFile(const FileLocation &location);
 	void fillFromFile(const QString &filePath);
 
@@ -66,7 +67,7 @@ private:
 
 	int64 _samplesCount = 0;
 	int32 _sampleRate = 0;
-	base::byte_vector _samples;
+	bytes::vector _samples;
 
 	TimeMs _peakDurationMs = 0;
 	int _peakEachPosition = 0;
diff --git a/Telegram/SourceFiles/media/media_child_ffmpeg_loader.cpp b/Telegram/SourceFiles/media/media_child_ffmpeg_loader.cpp
index 7820c1dae..16c824147 100644
--- a/Telegram/SourceFiles/media/media_child_ffmpeg_loader.cpp
+++ b/Telegram/SourceFiles/media/media_child_ffmpeg_loader.cpp
@@ -38,7 +38,7 @@ ChildFFMpegLoader::ChildFFMpegLoader(std::unique_ptr<VideoSoundData> &&data)
 : AbstractAudioFFMpegLoader(
 	FileLocation(),
 	QByteArray(),
-	base::byte_vector())
+	bytes::vector())
 , _parentData(std::move(data)) {
 }
 
diff --git a/Telegram/SourceFiles/mtproto/auth_key.h b/Telegram/SourceFiles/mtproto/auth_key.h
index 1cf08ecb1..c6a92eadc 100644
--- a/Telegram/SourceFiles/mtproto/auth_key.h
+++ b/Telegram/SourceFiles/mtproto/auth_key.h
@@ -60,15 +60,15 @@ public:
 		return other ? (_key == other->_key) : false;
 	}
 
-	static void FillData(Data &authKey, base::const_byte_span computedAuthKey) {
+	static void FillData(Data &authKey, bytes::const_span computedAuthKey) {
 		auto computedAuthKeySize = computedAuthKey.size();
 		Assert(computedAuthKeySize <= kSize);
 		auto authKeyBytes = gsl::make_span(authKey);
 		if (computedAuthKeySize < kSize) {
-			base::set_bytes(authKeyBytes.subspan(0, kSize - computedAuthKeySize), gsl::byte());
-			base::copy_bytes(authKeyBytes.subspan(kSize - computedAuthKeySize), computedAuthKey);
+			bytes::set_with_const(authKeyBytes.subspan(0, kSize - computedAuthKeySize), gsl::byte());
+			bytes::copy(authKeyBytes.subspan(kSize - computedAuthKeySize), computedAuthKey);
 		} else {
-			base::copy_bytes(authKeyBytes, computedAuthKey);
+			bytes::copy(authKeyBytes, computedAuthKey);
 		}
 	}
 
diff --git a/Telegram/SourceFiles/mtproto/connection.cpp b/Telegram/SourceFiles/mtproto/connection.cpp
index c9cbe3f83..174960c8c 100644
--- a/Telegram/SourceFiles/mtproto/connection.cpp
+++ b/Telegram/SourceFiles/mtproto/connection.cpp
@@ -139,7 +139,7 @@ bool IsPrimeAndGoodCheck(const openssl::BigNum &prime, int g) {
 	return true;
 }
 
-bool IsPrimeAndGood(base::const_byte_span primeBytes, int g) {
+bool IsPrimeAndGood(bytes::const_span primeBytes, int g) {
 	static constexpr unsigned char GoodPrime[] = {
 		0xC7, 0x1C, 0xAE, 0xB9, 0xC6, 0xB1, 0xC9, 0x04, 0x8E, 0x6C, 0x52, 0x2F, 0x70, 0xF1, 0x3F, 0x73,
 		0x98, 0x0D, 0x40, 0x23, 0x8E, 0x3E, 0x21, 0xC1, 0x49, 0x34, 0xD0, 0x37, 0x56, 0x3D, 0x93, 0x0F,
@@ -158,7 +158,7 @@ bool IsPrimeAndGood(base::const_byte_span primeBytes, int g) {
 		0x0D, 0x81, 0x15, 0xF6, 0x35, 0xB1, 0x05, 0xEE, 0x2E, 0x4E, 0x15, 0xD0, 0x4B, 0x24, 0x54, 0xBF,
 		0x6F, 0x4F, 0xAD, 0xF0, 0x34, 0xB1, 0x04, 0x03, 0x11, 0x9C, 0xD8, 0xE3, 0xB9, 0x2F, 0xCC, 0x5B };
 
-	if (!base::compare_bytes(gsl::as_bytes(gsl::make_span(GoodPrime)), primeBytes)) {
+	if (!bytes::compare(bytes::make_span(GoodPrime), primeBytes)) {
 		if (g == 3 || g == 4 || g == 5 || g == 7) {
 			return true;
 		}
@@ -167,31 +167,32 @@ bool IsPrimeAndGood(base::const_byte_span primeBytes, int g) {
 	return IsPrimeAndGoodCheck(openssl::BigNum(primeBytes), g);
 }
 
-std::vector<gsl::byte> CreateAuthKey(
-		base::const_byte_span firstBytes,
-		base::const_byte_span randomBytes,
-		base::const_byte_span primeBytes) {
+bytes::vector CreateAuthKey(
+		bytes::const_span firstBytes,
+		bytes::const_span randomBytes,
+		bytes::const_span primeBytes) {
 	using openssl::BigNum;
 	BigNum first(firstBytes);
 	BigNum prime(primeBytes);
 	if (!IsGoodModExpFirst(first, prime)) {
 		LOG(("AuthKey Error: Bad first prime in CreateAuthKey()."));
-		return std::vector<gsl::byte>();
+		return {};
 	}
 	return BigNum::ModExp(first, BigNum(randomBytes), prime).getBytes();
 }
 
 ModExpFirst CreateModExp(
 		int g,
-		base::const_byte_span primeBytes,
-		base::const_byte_span randomSeed) {
+		bytes::const_span primeBytes,
+		bytes::const_span randomSeed) {
 	Expects(randomSeed.size() == ModExpFirst::kRandomPowerSize);
 
 	using namespace openssl;
 
 	BigNum prime(primeBytes);
-	ModExpFirst result;
+	auto result = ModExpFirst();
 	constexpr auto kMaxModExpFirstTries = 5;
+	result.randomPower.resize(ModExpFirst::kRandomPowerSize);
 	for (auto tries = 0; tries != kMaxModExpFirstTries; ++tries) {
 		bytes::set_random(result.randomPower);
 		for (auto i = 0; i != ModExpFirst::kRandomPowerSize; ++i) {
@@ -2606,7 +2607,9 @@ void ConnectionPrivate::pqAnswered() {
 	sendRequestNotSecure(req_DH_params);
 }
 
-base::byte_vector ConnectionPrivate::encryptPQInnerRSA(const MTPP_Q_inner_data &data, const MTP::internal::RSAPublicKey &key) {
+bytes::vector ConnectionPrivate::encryptPQInnerRSA(
+		const MTPP_Q_inner_data &data,
+		const MTP::internal::RSAPublicKey &key) {
 	auto p_q_inner_size = data.innerLength();
 	auto encSize = (p_q_inner_size >> 2) + 6;
 	if (encSize >= 65) {
@@ -2615,7 +2618,7 @@ base::byte_vector ConnectionPrivate::encryptPQInnerRSA(const MTPP_Q_inner_data &
 		data.write(tmp);
 		LOG(("AuthKey Error: too large data for RSA encrypt, size %1").arg(encSize * sizeof(mtpPrime)));
 		DEBUG_LOG(("AuthKey Error: bad data for RSA encrypt %1").arg(Logs::mb(&tmp[0], tmp.size() * 4).str()));
-		return base::byte_vector(); // can't be 255-byte string
+		return {}; // can't be 255-byte string
 	}
 
 	auto encBuffer = mtpBuffer();
@@ -2630,7 +2633,7 @@ base::byte_vector ConnectionPrivate::encryptPQInnerRSA(const MTPP_Q_inner_data &
 		memset_rand(&encBuffer[encSize], (65 - encSize) * sizeof(mtpPrime));
 	}
 
-	auto bytes = gsl::as_bytes(gsl::make_span(encBuffer));
+	auto bytes = bytes::make_span(encBuffer);
 	auto bytesToEncrypt = bytes.subspan(3, 256);
 	return key.encrypt(bytesToEncrypt);
 }
@@ -2710,14 +2713,15 @@ void ConnectionPrivate::dhParamsAnswered() {
 		unixtimeSet(dh_inner_data.vserver_time.v);
 
 		// check that dhPrime and (dhPrime - 1) / 2 are really prime
-		if (!IsPrimeAndGood(bytesFromMTP(dh_inner_data.vdh_prime), dh_inner_data.vg.v)) {
+		if (!IsPrimeAndGood(bytes::make_span(dh_inner_data.vdh_prime.v), dh_inner_data.vg.v)) {
 			LOG(("AuthKey Error: bad dh_prime primality!"));
 			return restart();
 		}
 
-		_authKeyStrings->dh_prime = byteVectorFromMTP(dh_inner_data.vdh_prime);
+		_authKeyStrings->dh_prime = bytes::make_vector(
+			dh_inner_data.vdh_prime.v);
 		_authKeyData->g = dh_inner_data.vg.v;
-		_authKeyStrings->g_a = byteVectorFromMTP(dh_inner_data.vg_a);
+		_authKeyStrings->g_a = bytes::make_vector(dh_inner_data.vg_a.v);
 		_authKeyData->retry_id = MTP_long(0);
 		_authKeyData->retries = 0;
 	} return dhClientParamsSend();
@@ -2755,7 +2759,7 @@ void ConnectionPrivate::dhClientParamsSend() {
 	}
 
 	// gen rand 'b'
-	auto randomSeed = std::array<gsl::byte, ModExpFirst::kRandomPowerSize>();
+	auto randomSeed = bytes::vector(ModExpFirst::kRandomPowerSize);
 	bytes::set_random(randomSeed);
 	auto g_b_data = CreateModExp(_authKeyData->g, _authKeyStrings->dh_prime, randomSeed);
 	if (g_b_data.modexp.empty()) {
@@ -2957,7 +2961,7 @@ void ConnectionPrivate::authKeyCreated() {
 }
 
 void ConnectionPrivate::clearAuthKeyData() {
-	auto zeroMemory = [](base::byte_span bytes) {
+	auto zeroMemory = [](bytes::span bytes) {
 #ifdef Q_OS_WIN2
 		SecureZeroMemory(bytes.data(), bytes.size());
 #else // Q_OS_WIN
@@ -3227,15 +3231,15 @@ void ConnectionPrivate::stop() {
 
 } // namespace internal
 
-bool IsPrimeAndGood(base::const_byte_span primeBytes, int g) {
+bool IsPrimeAndGood(bytes::const_span primeBytes, int g) {
 	return internal::IsPrimeAndGood(primeBytes, g);
 }
 
-ModExpFirst CreateModExp(int g, base::const_byte_span primeBytes, base::const_byte_span randomSeed) {
+ModExpFirst CreateModExp(int g, bytes::const_span primeBytes, bytes::const_span randomSeed) {
 	return internal::CreateModExp(g, primeBytes, randomSeed);
 }
 
-std::vector<gsl::byte> CreateAuthKey(base::const_byte_span firstBytes, base::const_byte_span randomBytes, base::const_byte_span primeBytes) {
+bytes::vector CreateAuthKey(bytes::const_span firstBytes, bytes::const_span randomBytes, bytes::const_span primeBytes) {
 	return internal::CreateAuthKey(firstBytes, randomBytes, primeBytes);
 }
 
diff --git a/Telegram/SourceFiles/mtproto/connection.h b/Telegram/SourceFiles/mtproto/connection.h
index b61e0ba5c..d8628895c 100644
--- a/Telegram/SourceFiles/mtproto/connection.h
+++ b/Telegram/SourceFiles/mtproto/connection.h
@@ -16,15 +16,15 @@ namespace MTP {
 
 class Instance;
 
-bool IsPrimeAndGood(base::const_byte_span primeBytes, int g);
+bool IsPrimeAndGood(bytes::const_span primeBytes, int g);
 struct ModExpFirst {
 	static constexpr auto kRandomPowerSize = 256;
 
-	std::vector<gsl::byte> modexp;
-	std::array<gsl::byte, kRandomPowerSize> randomPower;
+	bytes::vector modexp;
+	bytes::vector randomPower;
 };
-ModExpFirst CreateModExp(int g, base::const_byte_span primeBytes, base::const_byte_span randomSeed);
-std::vector<gsl::byte> CreateAuthKey(base::const_byte_span firstBytes, base::const_byte_span randomBytes, base::const_byte_span primeBytes);
+ModExpFirst CreateModExp(int g, bytes::const_span primeBytes, bytes::const_span randomSeed);
+bytes::vector CreateAuthKey(bytes::const_span firstBytes, bytes::const_span randomBytes, bytes::const_span primeBytes);
 
 namespace internal {
 
@@ -190,7 +190,7 @@ private:
 
 	bool setState(int32 state, int32 ifState = Connection::UpdateAlways);
 
-	base::byte_vector encryptPQInnerRSA(const MTPP_Q_inner_data &data, const MTP::internal::RSAPublicKey &key);
+	bytes::vector encryptPQInnerRSA(const MTPP_Q_inner_data &data, const MTP::internal::RSAPublicKey &key);
 	std::string encryptClientDHInner(const MTPClient_DH_Inner_Data &data);
 	void appendTestConnection(
 		DcOptions::Variants::Protocol protocol,
@@ -286,8 +286,8 @@ private:
 		uint32 msgs_sent = 0;
 	};
 	struct AuthKeyCreateStrings {
-		std::vector<gsl::byte> dh_prime;
-		std::vector<gsl::byte> g_a;
+		bytes::vector dh_prime;
+		bytes::vector g_a;
 		AuthKey::Data auth_key = { { gsl::byte{} } };
 	};
 	std::unique_ptr<AuthKeyCreateData> _authKeyData;
diff --git a/Telegram/SourceFiles/mtproto/core_types.h b/Telegram/SourceFiles/mtproto/core_types.h
index e852d02de..3792e0c3f 100644
--- a/Telegram/SourceFiles/mtproto/core_types.h
+++ b/Telegram/SourceFiles/mtproto/core_types.h
@@ -9,6 +9,7 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "core/basic_types.h"
 #include "base/flags.h"
+#include "base/bytes.h"
 
 namespace MTP {
 
@@ -625,15 +626,13 @@ inline MTPbytes MTP_bytes(const QByteArray &v) {
 inline MTPbytes MTP_bytes(QByteArray &&v) {
 	return MTPbytes(std::move(v));
 }
-inline MTPbytes MTP_bytes(base::const_byte_span bytes) {
-	return MTP_bytes(QByteArray(reinterpret_cast<const char*>(bytes.data()), bytes.size()));
+inline MTPbytes MTP_bytes(bytes::const_span buffer) {
+	return MTP_bytes(QByteArray(
+		reinterpret_cast<const char*>(buffer.data()),
+		buffer.size()));
 }
-inline MTPbytes MTP_bytes(const std::vector<gsl::byte> &bytes) {
-	return MTP_bytes(gsl::make_span(bytes));
-}
-template <size_t N>
-inline MTPbytes MTP_bytes(const std::array<gsl::byte, N> &bytes) {
-	return MTP_bytes(gsl::make_span(bytes));
+inline MTPbytes MTP_bytes(const bytes::vector &buffer) {
+	return MTP_bytes(bytes::make_span(buffer));
 }
 
 inline bool operator==(const MTPstring &a, const MTPstring &b) {
@@ -651,15 +650,6 @@ inline QByteArray qba(const MTPstring &v) {
 	return v.v;
 }
 
-inline base::const_byte_span bytesFromMTP(const MTPbytes &v) {
-	return gsl::as_bytes(gsl::make_span(v.v));
-}
-
-inline std::vector<gsl::byte> byteVectorFromMTP(const MTPbytes &v) {
-	auto bytes = bytesFromMTP(v);
-	return std::vector<gsl::byte>(bytes.cbegin(), bytes.cend());
-}
-
 template <typename T>
 class MTPvector {
 public:
diff --git a/Telegram/SourceFiles/mtproto/dc_options.cpp b/Telegram/SourceFiles/mtproto/dc_options.cpp
index c24d206de..4ce82a8b1 100644
--- a/Telegram/SourceFiles/mtproto/dc_options.cpp
+++ b/Telegram/SourceFiles/mtproto/dc_options.cpp
@@ -89,8 +89,8 @@ private:
 
 void DcOptions::readBuiltInPublicKeys() {
 	for (const auto key : PublicRSAKeys) {
-		const auto keyBytes = gsl::make_span(key, key + strlen(key));
-		auto parsed = internal::RSAPublicKey(gsl::as_bytes(keyBytes));
+		const auto keyBytes = bytes::make_span(key, strlen(key));
+		auto parsed = internal::RSAPublicKey(keyBytes);
 		if (parsed.isValid()) {
 			_publicKeys.emplace(parsed.getFingerPrint(), std::move(parsed));
 		} else {
@@ -352,8 +352,8 @@ QByteArray DcOptions::serialize() const {
 	}
 	struct SerializedPublicKey {
 		DcId dcId;
-		base::byte_vector n;
-		base::byte_vector e;
+		bytes::vector n;
+		bytes::vector e;
 	};
 	std::vector<SerializedPublicKey> publicKeys;
 	publicKeys.reserve(count);
@@ -485,7 +485,7 @@ void DcOptions::constructFromSerialized(const QByteArray &serialized) {
 
 		for (auto i = 0; i != count; ++i) {
 			qint32 dcId = 0;
-			base::byte_vector n, e;
+			bytes::vector n, e;
 			stream >> dcId >> Serialize::bytes(n) >> Serialize::bytes(e);
 			if (stream.status() != QDataStream::Ok) {
 				LOG(("MTP Error: Bad data for CDN config inside DcOptions::constructFromSerialized()"));
@@ -540,8 +540,8 @@ void DcOptions::setCDNConfig(const MTPDcdnConfig &config) {
 	for_const (auto &publicKey, config.vpublic_keys.v) {
 		Expects(publicKey.type() == mtpc_cdnPublicKey);
 		const auto &keyData = publicKey.c_cdnPublicKey();
-		const auto keyBytes = gsl::make_span(keyData.vpublic_key.v);
-		auto key = internal::RSAPublicKey(gsl::as_bytes(keyBytes));
+		const auto keyBytes = bytes::make_span(keyData.vpublic_key.v);
+		auto key = internal::RSAPublicKey(keyBytes);
 		if (key.isValid()) {
 			_cdnPublicKeys[keyData.vdc_id.v].emplace(
 				key.getFingerPrint(),
diff --git a/Telegram/SourceFiles/mtproto/rsa_public_key.cpp b/Telegram/SourceFiles/mtproto/rsa_public_key.cpp
index 22cce6926..2ead24f7e 100644
--- a/Telegram/SourceFiles/mtproto/rsa_public_key.cpp
+++ b/Telegram/SourceFiles/mtproto/rsa_public_key.cpp
@@ -59,7 +59,7 @@ enum class Format {
 	Unknown,
 };
 
-Format GuessFormat(base::const_byte_span key) {
+Format GuessFormat(bytes::const_span key) {
 	const auto array = QByteArray::fromRawData(
 		reinterpret_cast<const char*>(key.data()),
 		key.size());
@@ -71,7 +71,7 @@ Format GuessFormat(base::const_byte_span key) {
 	return Format::Unknown;
 }
 
-RSA *CreateRaw(base::const_byte_span key) {
+RSA *CreateRaw(bytes::const_span key) {
 	const auto format = GuessFormat(key);
 	const auto bio = BIO_new_mem_buf(
 		const_cast<gsl::byte*>(key.data()),
@@ -89,13 +89,13 @@ RSA *CreateRaw(base::const_byte_span key) {
 
 class RSAPublicKey::Private {
 public:
-	Private(base::const_byte_span key)
+	Private(bytes::const_span key)
 	: _rsa(CreateRaw(key)) {
 		if (_rsa) {
 			computeFingerprint();
 		}
 	}
-	Private(base::const_byte_span nBytes, base::const_byte_span eBytes)
+	Private(bytes::const_span nBytes, bytes::const_span eBytes)
 	: _rsa(RSA_new()) {
 		if (_rsa) {
 			auto n = openssl::BigNum(nBytes).takeRaw();
@@ -110,14 +110,16 @@ public:
 			}
 		}
 	}
-	base::byte_vector getN() const {
+	bytes::vector getN() const {
 		Expects(isValid());
+
 		const BIGNUM *n;
 		RSA_get0_key(_rsa, &n, nullptr, nullptr);
 		return toBytes(n);
 	}
-	base::byte_vector getE() const {
+	bytes::vector getE() const {
 		Expects(isValid());
+
 		const BIGNUM *e;
 		RSA_get0_key(_rsa, nullptr, &e, nullptr);
 		return toBytes(e);
@@ -128,37 +130,37 @@ public:
 	bool isValid() const {
 		return _rsa != nullptr;
 	}
-	base::byte_vector encrypt(base::const_byte_span data) const {
+	bytes::vector encrypt(bytes::const_span data) const {
 		Expects(isValid());
 
 		constexpr auto kEncryptSize = 256;
-		auto result = base::byte_vector(kEncryptSize, gsl::byte {});
+		auto result = bytes::vector(kEncryptSize, gsl::byte {});
 		auto res = RSA_public_encrypt(kEncryptSize, reinterpret_cast<const unsigned char*>(data.data()), reinterpret_cast<unsigned char*>(result.data()), _rsa, RSA_NO_PADDING);
 		if (res < 0 || res > kEncryptSize) {
 			ERR_load_crypto_strings();
 			LOG(("RSA Error: RSA_public_encrypt failed, key fp: %1, result: %2, error: %3").arg(getFingerPrint()).arg(res).arg(ERR_error_string(ERR_get_error(), 0)));
-			return base::byte_vector();
+			return {};
 		} else if (auto zeroBytes = kEncryptSize - res) {
 			auto resultBytes = gsl::make_span(result);
-			base::move_bytes(resultBytes.subspan(zeroBytes, res), resultBytes.subspan(0, res));
-			base::set_bytes(resultBytes.subspan(0, zeroBytes), gsl::byte {});
+			bytes::move(resultBytes.subspan(zeroBytes, res), resultBytes.subspan(0, res));
+			bytes::set_with_const(resultBytes.subspan(0, zeroBytes), gsl::byte {});
 		}
 		return result;
 	}
-	base::byte_vector decrypt(base::const_byte_span data) const {
+	bytes::vector decrypt(bytes::const_span data) const {
 		Expects(isValid());
 
 		constexpr auto kDecryptSize = 256;
-		auto result = base::byte_vector(kDecryptSize, gsl::byte {});
+		auto result = bytes::vector(kDecryptSize, gsl::byte {});
 		auto res = RSA_public_decrypt(kDecryptSize, reinterpret_cast<const unsigned char*>(data.data()), reinterpret_cast<unsigned char*>(result.data()), _rsa, RSA_NO_PADDING);
 		if (res < 0 || res > kDecryptSize) {
 			ERR_load_crypto_strings();
 			LOG(("RSA Error: RSA_public_encrypt failed, key fp: %1, result: %2, error: %3").arg(getFingerPrint()).arg(res).arg(ERR_error_string(ERR_get_error(), 0)));
-			return base::byte_vector();
+			return {};
 		} else if (auto zeroBytes = kDecryptSize - res) {
 			auto resultBytes = gsl::make_span(result);
-			base::move_bytes(resultBytes.subspan(zeroBytes - res, res), resultBytes.subspan(0, res));
-			base::set_bytes(resultBytes.subspan(0, zeroBytes - res), gsl::byte {});
+			bytes::move(resultBytes.subspan(zeroBytes - res, res), resultBytes.subspan(0, res));
+			bytes::set_with_const(resultBytes.subspan(0, zeroBytes - res), gsl::byte {});
 		}
 		return result;
 	}
@@ -179,9 +181,9 @@ private:
 		uchar sha1Buffer[20];
 		_fingerprint = *(uint64*)(hashSha1(&string[0], string.size() * sizeof(mtpPrime), sha1Buffer) + 3);
 	}
-	static base::byte_vector toBytes(const BIGNUM *number) {
+	static bytes::vector toBytes(const BIGNUM *number) {
 		auto size = BN_num_bytes(number);
-		auto result = base::byte_vector(size, gsl::byte {});
+		auto result = bytes::vector(size, gsl::byte {});
 		BN_bn2bin(number, reinterpret_cast<unsigned char*>(result.data()));
 		return result;
 	}
@@ -191,13 +193,13 @@ private:
 
 };
 
-RSAPublicKey::RSAPublicKey(base::const_byte_span key)
+RSAPublicKey::RSAPublicKey(bytes::const_span key)
 : _private(std::make_shared<Private>(key)) {
 }
 
 RSAPublicKey::RSAPublicKey(
-	base::const_byte_span nBytes,
-	base::const_byte_span eBytes)
+	bytes::const_span nBytes,
+	bytes::const_span eBytes)
 : _private(std::make_shared<Private>(nBytes, eBytes)) {
 }
 
@@ -210,23 +212,27 @@ uint64 RSAPublicKey::getFingerPrint() const {
 	return _private->getFingerPrint();
 }
 
-base::byte_vector RSAPublicKey::getN() const {
+bytes::vector RSAPublicKey::getN() const {
 	Expects(isValid());
+
 	return _private->getN();
 }
 
-base::byte_vector RSAPublicKey::getE() const {
+bytes::vector RSAPublicKey::getE() const {
 	Expects(isValid());
+
 	return _private->getE();
 }
 
-base::byte_vector RSAPublicKey::encrypt(base::const_byte_span data) const {
+bytes::vector RSAPublicKey::encrypt(bytes::const_span data) const {
 	Expects(isValid());
+
 	return _private->encrypt(data);
 }
 
-base::byte_vector RSAPublicKey::decrypt(base::const_byte_span data) const {
+bytes::vector RSAPublicKey::decrypt(bytes::const_span data) const {
 	Expects(isValid());
+
 	return _private->decrypt(data);
 }
 
diff --git a/Telegram/SourceFiles/mtproto/rsa_public_key.h b/Telegram/SourceFiles/mtproto/rsa_public_key.h
index c34fbaa96..7c03914b8 100644
--- a/Telegram/SourceFiles/mtproto/rsa_public_key.h
+++ b/Telegram/SourceFiles/mtproto/rsa_public_key.h
@@ -7,6 +7,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 */
 #pragma once
 
+#include "base/bytes.h"
+
 namespace MTP {
 namespace internal {
 
@@ -14,7 +16,7 @@ namespace internal {
 class RSAPublicKey final {
 public:
 	RSAPublicKey() = default;
-	RSAPublicKey(base::const_byte_span nBytes, base::const_byte_span eBytes);
+	RSAPublicKey(bytes::const_span nBytes, bytes::const_span eBytes);
 	RSAPublicKey(RSAPublicKey &&other) = default;
 	RSAPublicKey(const RSAPublicKey &other) = default;
 	RSAPublicKey &operator=(RSAPublicKey &&other) = default;
@@ -22,18 +24,18 @@ public:
 
 	// key in "-----BEGIN RSA PUBLIC KEY----- ..." format
 	// or in "-----BEGIN PUBLIC KEY----- ..." format
-	explicit RSAPublicKey(base::const_byte_span key);
+	explicit RSAPublicKey(bytes::const_span key);
 
 	bool isValid() const;
 	uint64 getFingerPrint() const;
-	base::byte_vector getN() const;
-	base::byte_vector getE() const;
+	bytes::vector getN() const;
+	bytes::vector getE() const;
 
 	// data has exactly 256 chars to be encrypted
-	base::byte_vector encrypt(base::const_byte_span data) const;
+	bytes::vector encrypt(bytes::const_span data) const;
 
 	// data has exactly 256 chars to be decrypted
-	base::byte_vector decrypt(base::const_byte_span data) const;
+	bytes::vector decrypt(bytes::const_span data) const;
 
 private:
 	class Private;
diff --git a/Telegram/SourceFiles/mtproto/session.cpp b/Telegram/SourceFiles/mtproto/session.cpp
index 4dcd4b4a8..54d5e199b 100644
--- a/Telegram/SourceFiles/mtproto/session.cpp
+++ b/Telegram/SourceFiles/mtproto/session.cpp
@@ -286,16 +286,13 @@ void Session::sendPong(quint64 msgId, quint64 pingId) {
 }
 
 void Session::sendMsgsStateInfo(quint64 msgId, QByteArray data) {
-	auto info = std::string();
+	auto info = bytes::vector();
 	if (!data.isEmpty()) {
 		info.resize(data.size());
-		auto src = gsl::as_bytes(gsl::make_span(data));
-//		auto dst = gsl::as_writeable_bytes(gsl::make_span(info));
-		auto dst = gsl::as_writeable_bytes(gsl::make_span(&info[0], info.size()));
-		base::copy_bytes(dst, src);
+		bytes::copy(info, bytes::make_span(data));
 	}
 	send(mtpRequestData::serialize(MTPMsgsStateInfo(
-		MTP_msgs_state_info(MTP_long(msgId), MTP_string(std::move(info))))));
+		MTP_msgs_state_info(MTP_long(msgId), MTP_bytes(data)))));
 }
 
 void Session::checkRequestsByTimer() {
diff --git a/Telegram/SourceFiles/mtproto/special_config_request.cpp b/Telegram/SourceFiles/mtproto/special_config_request.cpp
index 4d04783df..9eaead5f1 100644
--- a/Telegram/SourceFiles/mtproto/special_config_request.cpp
+++ b/Telegram/SourceFiles/mtproto/special_config_request.cpp
@@ -276,33 +276,30 @@ bool SpecialConfigRequest::decryptSimpleConfig(const QByteArray &bytes) {
 		return false;
 	}
 
-	auto publicKey = internal::RSAPublicKey(gsl::as_bytes(gsl::make_span(
+	auto publicKey = internal::RSAPublicKey(bytes::make_span(
 		kPublicKey.c_str(),
-		kPublicKey.size())));
-	auto decrypted = publicKey.decrypt(gsl::as_bytes(gsl::make_span(decodedBytes)));
+		kPublicKey.size()));
+	auto decrypted = publicKey.decrypt(bytes::make_span(decodedBytes));
 	auto decryptedBytes = gsl::make_span(decrypted);
 
-	constexpr auto kAesKeySize = CTRState::KeySize;
-	constexpr auto kAesIvecSize = CTRState::IvecSize;
-	auto aesEncryptedBytes = decryptedBytes.subspan(kAesKeySize);
-	base::byte_array<kAesIvecSize> aesivec;
-	base::copy_bytes(aesivec, decryptedBytes.subspan(CTRState::KeySize - CTRState::IvecSize, CTRState::IvecSize));
+	auto aesEncryptedBytes = decryptedBytes.subspan(CTRState::KeySize);
+	auto aesivec = bytes::make_vector(decryptedBytes.subspan(CTRState::KeySize - CTRState::IvecSize, CTRState::IvecSize));
 	AES_KEY aeskey;
-	AES_set_decrypt_key(reinterpret_cast<const unsigned char*>(decryptedBytes.data()), kAesKeySize * CHAR_BIT, &aeskey);
+	AES_set_decrypt_key(reinterpret_cast<const unsigned char*>(decryptedBytes.data()), CTRState::KeySize * CHAR_BIT, &aeskey);
 	AES_cbc_encrypt(reinterpret_cast<const unsigned char*>(aesEncryptedBytes.data()), reinterpret_cast<unsigned char*>(aesEncryptedBytes.data()), aesEncryptedBytes.size(), &aeskey, reinterpret_cast<unsigned char*>(aesivec.data()), AES_DECRYPT);
 
 	constexpr auto kDigestSize = 16;
 	auto dataSize = aesEncryptedBytes.size() - kDigestSize;
 	auto data = aesEncryptedBytes.subspan(0, dataSize);
 	auto hash = openssl::Sha256(data);
-	if (base::compare_bytes(gsl::make_span(hash).subspan(0, kDigestSize), aesEncryptedBytes.subspan(dataSize)) != 0) {
+	if (bytes::compare(gsl::make_span(hash).subspan(0, kDigestSize), aesEncryptedBytes.subspan(dataSize)) != 0) {
 		LOG(("Config Error: Bad digest."));
 		return false;
 	}
 
 	mtpBuffer buffer;
 	buffer.resize(data.size() / sizeof(mtpPrime));
-	base::copy_bytes(gsl::as_writeable_bytes(gsl::make_span(buffer)), data);
+	bytes::copy(bytes::make_span(buffer), data);
 	auto from = &*buffer.cbegin();
 	auto end = from + buffer.size();
 	auto realLength = *from++;
diff --git a/Telegram/SourceFiles/passport/passport_encryption.cpp b/Telegram/SourceFiles/passport/passport_encryption.cpp
index e9113fbbe..928fa895e 100644
--- a/Telegram/SourceFiles/passport/passport_encryption.cpp
+++ b/Telegram/SourceFiles/passport/passport_encryption.cpp
@@ -9,9 +9,6 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 #include "base/openssl_help.h"
 
-#include <openssl/aes.h>
-#include <openssl/crypto.h>
-
 namespace Passport {
 namespace {
 
@@ -25,27 +22,27 @@ constexpr auto kAlignTo = 16;
 } // namespace
 
 struct AesParams {
-	base::byte_array<kAesKeyLength> key;
-	base::byte_array<kAesIvLength> iv;
+	bytes::vector key;
+	bytes::vector iv;
 };
 
-AesParams PrepareAesParams(base::const_byte_span secretHash) {
+AesParams PrepareAesParams(bytes::const_span secretHash) {
 	const auto hash = openssl::Sha512(secretHash);
 	const auto view = gsl::make_span(hash);
-	const auto key = view.subspan(0, kAesKeyLength);
-	const auto iv = view.subspan(kAesKeyLength, kAesIvLength);
 
 	auto result = AesParams();
-	base::copy_bytes(result.key, view.subspan(0, kAesKeyLength));
-	base::copy_bytes(result.iv, view.subspan(kAesKeyLength, kAesIvLength));
+	result.key = bytes::make_vector(view.subspan(0, kAesKeyLength));
+	result.iv = bytes::make_vector(view.subspan(kAesKeyLength, kAesIvLength));
 	return result;
 }
 
-base::byte_vector EncryptOrDecrypt(
-		base::const_byte_span initial,
+bytes::vector EncryptOrDecrypt(
+		bytes::const_span initial,
 		AesParams &&params,
 		int encryptOrDecrypt) {
 	Expects((initial.size() & 0x0F) == 0);
+	Expects(params.key.size() == kAesKeyLength);
+	Expects(params.iv.size() == kAesIvLength);
 
 	auto aesKey = AES_KEY();
 	const auto error = (encryptOrDecrypt == AES_ENCRYPT)
@@ -62,7 +59,7 @@ base::byte_vector EncryptOrDecrypt(
 			).arg(error));
 		return {};
 	}
-	auto result = base::byte_vector(initial.size());
+	auto result = bytes::vector(initial.size());
 	AES_cbc_encrypt(
 		reinterpret_cast<const uchar*>(initial.data()),
 		reinterpret_cast<uchar*>(result.data()),
@@ -73,27 +70,27 @@ base::byte_vector EncryptOrDecrypt(
 	return result;
 }
 
-base::byte_vector Encrypt(
-		base::const_byte_span decrypted,
+bytes::vector Encrypt(
+		bytes::const_span decrypted,
 		AesParams &&params) {
 	return EncryptOrDecrypt(decrypted, std::move(params), AES_ENCRYPT);
 }
 
-base::byte_vector Decrypt(
-		base::const_byte_span encrypted,
+bytes::vector Decrypt(
+		bytes::const_span encrypted,
 		AesParams &&params) {
 	return EncryptOrDecrypt(encrypted, std::move(params), AES_DECRYPT);
 }
 
-base::byte_vector PasswordHashForSecret(
-		base::const_byte_span passwordUtf8) {
+bytes::vector PasswordHashForSecret(
+		bytes::const_span passwordUtf8) {
 	//new_secure_salt = new_salt + random_bytes(8) // #TODO
 	//password_hash = SHA512(new_secure_salt + password + new_secure_salt)
 	const auto result = openssl::Sha512(passwordUtf8);
 	return { result.begin(), result.end() };
 }
 
-bool CheckBytesMod255(base::const_byte_span bytes) {
+bool CheckBytesMod255(bytes::const_span bytes) {
 	const auto full = ranges::accumulate(
 		bytes,
 		0ULL,
@@ -102,12 +99,12 @@ bool CheckBytesMod255(base::const_byte_span bytes) {
 	return (mod == 239);
 }
 
-bool CheckSecretBytes(base::const_byte_span secret) {
+bool CheckSecretBytes(bytes::const_span secret) {
 	return CheckBytesMod255(secret);
 }
 
-base::byte_vector GenerateSecretBytes() {
-	auto result = base::byte_vector(kSecretSize);
+bytes::vector GenerateSecretBytes() {
+	auto result = bytes::vector(kSecretSize);
 	memset_rand(result.data(), result.size());
 	const auto full = ranges::accumulate(
 		result,
@@ -120,9 +117,9 @@ base::byte_vector GenerateSecretBytes() {
 	return result;
 }
 
-base::byte_vector DecryptSecretBytes(
-		base::const_byte_span encryptedSecret,
-		base::const_byte_span passwordHashForSecret) {
+bytes::vector DecryptSecretBytes(
+		bytes::const_span encryptedSecret,
+		bytes::const_span passwordHashForSecret) {
 	if (encryptedSecret.empty()) {
 		return {};
 	} else if (encryptedSecret.size() != kSecretSize) {
@@ -139,9 +136,9 @@ base::byte_vector DecryptSecretBytes(
 	return result;
 }
 
-base::byte_vector EncryptSecretBytes(
-		base::const_byte_span secret,
-		base::const_byte_span passwordHashForSecret) {
+bytes::vector EncryptSecretBytes(
+		bytes::const_span secret,
+		bytes::const_span passwordHashForSecret) {
 	Expects(secret.size() == kSecretSize);
 	Expects(CheckSecretBytes(secret) == true);
 
@@ -149,27 +146,26 @@ base::byte_vector EncryptSecretBytes(
 	return Encrypt(secret, std::move(params));
 }
 
-base::byte_vector Concatenate(
-		base::const_byte_span a,
-		base::const_byte_span b) {
-	auto result = base::byte_vector(a.size() + b.size());
-	base::copy_bytes(result, a);
-	base::copy_bytes(gsl::make_span(result).subspan(a.size()), b);
+bytes::vector Concatenate(
+		bytes::const_span a,
+		bytes::const_span b) {
+	auto result = bytes::vector(a.size() + b.size());
+	bytes::copy(result, a);
+	bytes::copy(gsl::make_span(result).subspan(a.size()), b);
 	return result;
 }
 
-base::byte_vector SerializeData(const std::map<QString, QString> &data) {
+bytes::vector SerializeData(const std::map<QString, QString> &data) {
 	auto root = QJsonObject();
 	for (const auto &[key, value] : data) {
 		root.insert(key, value);
 	}
 	auto document = QJsonDocument(root);
 	const auto result = document.toJson(QJsonDocument::Compact);
-	const auto bytes = gsl::as_bytes(gsl::make_span(result));
-	return { bytes.begin(), bytes.end() };
+	return bytes::make_vector(result);
 }
 
-std::map<QString, QString> DeserializeData(base::const_byte_span bytes) {
+std::map<QString, QString> DeserializeData(bytes::const_span bytes) {
 	const auto serialized = QByteArray::fromRawData(
 		reinterpret_cast<const char*>(bytes.data()),
 		bytes.size());
@@ -226,13 +222,13 @@ std::map<QString, QString> DeserializeData(base::const_byte_span bytes) {
 	return result;
 }
 
-EncryptedData EncryptData(base::const_byte_span bytes) {
+EncryptedData EncryptData(bytes::const_span bytes) {
 	return EncryptData(bytes, GenerateSecretBytes());
 }
 
 EncryptedData EncryptData(
-		base::const_byte_span bytes,
-		base::const_byte_span dataSecret) {
+		bytes::const_span bytes,
+		bytes::const_span dataSecret) {
 	constexpr auto kFromPadding = kMinPadding + kAlignTo - 1;
 	constexpr auto kPaddingDelta = kMaxPadding - kFromPadding;
 	const auto randomPadding = kFromPadding
@@ -241,12 +237,12 @@ EncryptedData EncryptData(
 		- ((bytes.size() + randomPadding) % kAlignTo);
 	Assert(padding >= kMinPadding && padding <= kMaxPadding);
 
-	auto unencrypted = base::byte_vector(padding + bytes.size());
+	auto unencrypted = bytes::vector(padding + bytes.size());
 	Assert(unencrypted.size() % kAlignTo == 0);
 
 	unencrypted[0] = static_cast<gsl::byte>(padding);
 	memset_rand(unencrypted.data() + 1, padding - 1);
-	base::copy_bytes(
+	bytes::copy(
 		gsl::make_span(unencrypted).subspan(padding),
 		bytes);
 	const auto dataHash = openssl::Sha256(unencrypted);
@@ -261,10 +257,10 @@ EncryptedData EncryptData(
 	};
 }
 
-base::byte_vector DecryptData(
-		base::const_byte_span encrypted,
-		base::const_byte_span dataHash,
-		base::const_byte_span dataSecret) {
+bytes::vector DecryptData(
+		bytes::const_span encrypted,
+		bytes::const_span dataHash,
+		bytes::const_span dataSecret) {
 	constexpr auto kDataHashSize = 32;
 	if (encrypted.empty()) {
 		return {};
@@ -280,7 +276,7 @@ base::byte_vector DecryptData(
 		Concatenate(dataSecret, dataHash));
 	auto params = PrepareAesParams(dataSecretHash);
 	const auto decrypted = Decrypt(encrypted, std::move(params));
-	if (base::compare_bytes(openssl::Sha256(decrypted), dataHash) != 0) {
+	if (bytes::compare(openssl::Sha256(decrypted), dataHash) != 0) {
 		LOG(("API Error: Bad data hash."));
 		return {};
 	}
@@ -295,17 +291,17 @@ base::byte_vector DecryptData(
 	return { bytes.begin(), bytes.end() };
 }
 
-base::byte_vector PrepareValueHash(
-		base::const_byte_span dataHash,
-		base::const_byte_span valueSecret) {
+bytes::vector PrepareValueHash(
+		bytes::const_span dataHash,
+		bytes::const_span valueSecret) {
 	const auto result = openssl::Sha256(Concatenate(dataHash, valueSecret));
 	return { result.begin(), result.end() };
 }
 
-base::byte_vector PrepareFilesHash(
-		gsl::span<base::const_byte_span> fileHashes,
-		base::const_byte_span valueSecret) {
-	auto resultInner = base::byte_vector{
+bytes::vector PrepareFilesHash(
+		gsl::span<bytes::const_span> fileHashes,
+		bytes::const_span valueSecret) {
+	auto resultInner = bytes::vector{
 		valueSecret.begin(),
 		valueSecret.end()
 	};
@@ -316,19 +312,19 @@ base::byte_vector PrepareFilesHash(
 	return { result.begin(), result.end() };
 }
 
-base::byte_vector EncryptValueSecret(
-		base::const_byte_span valueSecret,
-		base::const_byte_span secret,
-		base::const_byte_span valueHash) {
+bytes::vector EncryptValueSecret(
+		bytes::const_span valueSecret,
+		bytes::const_span secret,
+		bytes::const_span valueHash) {
 	const auto valueSecretHash = openssl::Sha512(
 		Concatenate(secret, valueHash));
 	return EncryptSecretBytes(valueSecret, valueSecretHash);
 }
 
-base::byte_vector DecryptValueSecret(
-		base::const_byte_span encrypted,
-		base::const_byte_span secret,
-		base::const_byte_span valueHash) {
+bytes::vector DecryptValueSecret(
+		bytes::const_span encrypted,
+		bytes::const_span secret,
+		bytes::const_span valueHash) {
 	const auto valueSecretHash = openssl::Sha512(
 		Concatenate(secret, valueHash));
 	return DecryptSecretBytes(encrypted, valueSecretHash);
diff --git a/Telegram/SourceFiles/passport/passport_encryption.h b/Telegram/SourceFiles/passport/passport_encryption.h
index 987416f20..02e6e18f3 100644
--- a/Telegram/SourceFiles/passport/passport_encryption.h
+++ b/Telegram/SourceFiles/passport/passport_encryption.h
@@ -9,53 +9,53 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 
 namespace Passport {
 
-base::byte_vector GenerateSecretBytes();
+bytes::vector GenerateSecretBytes();
 
-base::byte_vector EncryptSecretBytes(
-	base::const_byte_span secret,
-	base::const_byte_span passwordHashForSecret);
-base::byte_vector DecryptSecretBytes(
-	base::const_byte_span encryptedSecret,
-	base::const_byte_span passwordHashForSecret);
+bytes::vector EncryptSecretBytes(
+	bytes::const_span secret,
+	bytes::const_span passwordHashForSecret);
+bytes::vector DecryptSecretBytes(
+	bytes::const_span encryptedSecret,
+	bytes::const_span passwordHashForSecret);
 
-base::byte_vector PasswordHashForSecret(base::const_byte_span passwordUtf8);
+bytes::vector PasswordHashForSecret(bytes::const_span passwordUtf8);
 
-base::byte_vector SerializeData(const std::map<QString, QString> &data);
-std::map<QString, QString> DeserializeData(base::const_byte_span bytes);
+bytes::vector SerializeData(const std::map<QString, QString> &data);
+std::map<QString, QString> DeserializeData(bytes::const_span bytes);
 
 struct EncryptedData {
-	base::byte_vector secret;
-	base::byte_vector hash;
-	base::byte_vector bytes;
+	bytes::vector secret;
+	bytes::vector hash;
+	bytes::vector bytes;
 };
 
-EncryptedData EncryptData(base::const_byte_span bytes);
+EncryptedData EncryptData(bytes::const_span bytes);
 
 EncryptedData EncryptData(
-	base::const_byte_span bytes,
-	base::const_byte_span dataSecret);
+	bytes::const_span bytes,
+	bytes::const_span dataSecret);
 
-base::byte_vector DecryptData(
-	base::const_byte_span encrypted,
-	base::const_byte_span dataHash,
-	base::const_byte_span dataSecret);
+bytes::vector DecryptData(
+	bytes::const_span encrypted,
+	bytes::const_span dataHash,
+	bytes::const_span dataSecret);
 
-base::byte_vector PrepareValueHash(
-	base::const_byte_span dataHash,
-	base::const_byte_span valueSecret);
+bytes::vector PrepareValueHash(
+	bytes::const_span dataHash,
+	bytes::const_span valueSecret);
 
-base::byte_vector EncryptValueSecret(
-	base::const_byte_span valueSecret,
-	base::const_byte_span secret,
-	base::const_byte_span valueHash);
+bytes::vector EncryptValueSecret(
+	bytes::const_span valueSecret,
+	bytes::const_span secret,
+	bytes::const_span valueHash);
 
-base::byte_vector DecryptValueSecret(
-	base::const_byte_span encrypted,
-	base::const_byte_span secret,
-	base::const_byte_span valueHash);
+bytes::vector DecryptValueSecret(
+	bytes::const_span encrypted,
+	bytes::const_span secret,
+	bytes::const_span valueHash);
 
-base::byte_vector PrepareFilesHash(
-	gsl::span<base::const_byte_span> fileHashes,
-	base::const_byte_span valueSecret);
+bytes::vector PrepareFilesHash(
+	gsl::span<bytes::const_span> fileHashes,
+	bytes::const_span valueSecret);
 
 } // namespace Passport
diff --git a/Telegram/SourceFiles/passport/passport_form_controller.cpp b/Telegram/SourceFiles/passport/passport_form_controller.cpp
index e42945e8e..f8823071d 100644
--- a/Telegram/SourceFiles/passport/passport_form_controller.cpp
+++ b/Telegram/SourceFiles/passport/passport_form_controller.cpp
@@ -49,12 +49,13 @@ FormController::Field::Field(Type type) : type(type) {
 }
 
 template <typename FileHashes>
-base::byte_vector FormController::computeFilesHash(
+bytes::vector FormController::computeFilesHash(
 		FileHashes fileHashes,
-		base::const_byte_span valueSecret) {
-	auto hashesVector = std::vector<base::const_byte_span>();
+		bytes::const_span valueSecret) {
+	auto vec = bytes::concatenate(fileHashes);
+	auto hashesVector = std::vector<bytes::const_span>();
 	for (const auto &hash : fileHashes) {
-		hashesVector.push_back(gsl::as_bytes(gsl::make_span(hash)));
+		hashesVector.push_back(bytes::make_span(hash));
 	}
 	return PrepareFilesHash(hashesVector, valueSecret);
 }
@@ -82,9 +83,10 @@ void FormController::submitPassword(const QString &password) {
 		_passwordError.fire(QString());
 	}
 	const auto passwordBytes = password.toUtf8();
-	const auto data = _password.salt + passwordBytes + _password.salt;
-	const auto hash = openssl::Sha256(gsl::as_bytes(gsl::make_span(data)));
-	_passwordHashForAuth = { hash.begin(), hash.end() };
+	_passwordHashForAuth = openssl::Sha256(bytes::concatenate(
+		bytes::make_span(_password.salt),
+		bytes::make_span(passwordBytes),
+		bytes::make_span(_password.salt)));
 	_passwordCheckRequestId = request(MTPaccount_GetPasswordSettings(
 		MTP_bytes(_passwordHashForAuth)
 	)).handleFloodErrors(
@@ -94,17 +96,16 @@ void FormController::submitPassword(const QString &password) {
 		_passwordCheckRequestId = 0;
 		const auto &data = result.c_account_passwordSettings();
 		_passwordEmail = qs(data.vemail);
-		const auto hash = openssl::Sha512(gsl::as_bytes(gsl::make_span(passwordBytes)));
-		_passwordHashForSecret = { hash.begin(), hash.end() };
+		_passwordHashForSecret = openssl::Sha512(bytes::make_span(passwordBytes));
 		_secret = DecryptSecretBytes(
-			bytesFromMTP(data.vsecure_secret),
+			bytes::make_span(data.vsecure_secret.v),
 			_passwordHashForSecret);
 		for (auto &field : _form.fields) {
 			field.data.values = fillData(field.data);
 			if (auto &document = field.document) {
-				const auto filesHash = gsl::as_bytes(gsl::make_span(document->filesHash));
+				const auto filesHash = bytes::make_span(document->filesHash);
 				document->filesSecret = DecryptValueSecret(
-					gsl::as_bytes(gsl::make_span(document->filesSecretEncrypted)),
+					bytes::make_span(document->filesSecretEncrypted),
 					_secret,
 					filesHash);
 				if (document->filesSecret.empty()
@@ -154,7 +155,7 @@ void FormController::uploadScan(int index, QByteArray &&content) {
 		filesSecret = document.filesSecret
 	] {
 		auto data = EncryptData(
-			gsl::as_bytes(gsl::make_span(bytes)),
+			bytes::make_span(bytes),
 			filesSecret);
 		auto result = UploadedScan();
 		result.fileId = rand_value<uint64>();
@@ -350,7 +351,7 @@ void FormController::loadFiles(const std::vector<File> &files) {
 void FormController::fileLoaded(FileKey key, const QByteArray &bytes) {
 	if (const auto [field, file] = findFile(key); file != nullptr) {
 		const auto decrypted = DecryptData(
-			gsl::as_bytes(gsl::make_span(bytes)),
+			bytes::make_span(bytes),
 			file->fileHash,
 			field->document->filesSecret);
 		auto image = App::readImage(QByteArray::fromRawData(
@@ -413,13 +414,13 @@ std::map<QString, QString> FormController::fillData(
 	if (from.dataEncrypted.isEmpty()) {
 		return {};
 	}
-	const auto valueHash = gsl::as_bytes(gsl::make_span(from.dataHash));
+	const auto valueHash = bytes::make_span(from.dataHash);
 	const auto valueSecret = DecryptValueSecret(
-		gsl::as_bytes(gsl::make_span(from.dataSecretEncrypted)),
+		bytes::make_span(from.dataSecretEncrypted),
 		_secret,
 		valueHash);
 	return DeserializeData(DecryptData(
-		gsl::as_bytes(gsl::make_span(from.dataEncrypted)),
+		bytes::make_span(from.dataEncrypted),
 		valueHash,
 		valueSecret));
 }
@@ -490,7 +491,7 @@ void FormController::saveFiles(int index) {
 		ranges::view::all(
 			document.filesInEdit
 		) | ranges::view::transform([=](const EditFile &file) {
-			return gsl::as_bytes(gsl::make_span(file.fields.fileHash));
+			return bytes::make_span(file.fields.fileHash);
 		}),
 		document.filesSecret);
 
@@ -714,7 +715,7 @@ auto FormController::convertValue(
 				if (normal.fileHash.size() != 32) {
 					normal.fileHash.clear();
 				}
-//				normal.fileHash = byteVectorFromMTP(fields.vfile_hash);
+//				normal.fileHash = bytes::make_vector(fields.vfile_hash.v);
 				result.files.push_back(std::move(normal));
 			} break;
 			}
@@ -837,8 +838,7 @@ void FormController::passwordFail(const RPCError &error) {
 void FormController::parsePassword(const MTPDaccount_noPassword &result) {
 	_password.unconfirmedPattern = qs(result.vemail_unconfirmed_pattern);
 	_password.newSalt = result.vnew_salt.v;
-	openssl::AddRandomSeed(
-		gsl::as_bytes(gsl::make_span(result.vsecret_random.v)));
+	openssl::AddRandomSeed(bytes::make_span(result.vsecret_random.v));
 }
 
 void FormController::parsePassword(const MTPDaccount_password &result) {
@@ -847,8 +847,7 @@ void FormController::parsePassword(const MTPDaccount_password &result) {
 	_password.salt = result.vcurrent_salt.v;
 	_password.unconfirmedPattern = qs(result.vemail_unconfirmed_pattern);
 	_password.newSalt = result.vnew_salt.v;
-	openssl::AddRandomSeed(
-		gsl::as_bytes(gsl::make_span(result.vsecret_random.v)));
+	openssl::AddRandomSeed(bytes::make_span(result.vsecret_random.v));
 }
 
 FormController::~FormController() = default;
diff --git a/Telegram/SourceFiles/passport/passport_form_controller.h b/Telegram/SourceFiles/passport/passport_form_controller.h
index 24dd3ba0a..54ab8146c 100644
--- a/Telegram/SourceFiles/passport/passport_form_controller.h
+++ b/Telegram/SourceFiles/passport/passport_form_controller.h
@@ -109,16 +109,16 @@ private:
 		uint64 fileId = 0;
 		int partsCount = 0;
 		QByteArray md5checksum;
-		base::byte_vector hash;
-		base::byte_vector bytes;
+		bytes::vector hash;
+		bytes::vector bytes;
 	};
 	struct File {
 		uint64 id = 0;
 		uint64 accessHash = 0;
 		int32 size = 0;
 		int32 dcId = 0;
-		base::byte_vector fileHash;
-		base::byte_vector bytes;
+		bytes::vector fileHash;
+		bytes::vector bytes;
 	};
 	struct EditFile {
 		EditFile(
@@ -142,7 +142,7 @@ private:
 		std::vector<File> files;
 		QByteArray filesHash;
 		QByteArray filesSecretEncrypted;
-		base::byte_vector filesSecret;
+		bytes::vector filesSecret;
 
 		std::vector<EditFile> filesInEdit;
 	};
@@ -199,9 +199,9 @@ private:
 	void generateSecret(base::lambda<void()> callback);
 
 	template <typename FileHashes>
-	base::byte_vector computeFilesHash(
+	bytes::vector computeFilesHash(
 		FileHashes fileHashes,
-		base::const_byte_span valueHash);
+		bytes::const_span valueHash);
 
 	void subscribeToUploader();
 	void uploadEncryptedScan(int index, UploadedScan &&data);
@@ -221,9 +221,9 @@ private:
 	std::map<FileKey, std::unique_ptr<mtpFileLoader>> _fileLoaders;
 	rpl::event_stream<ScanInfo> _scanUpdated;
 
-	base::byte_vector _passwordHashForSecret;
-	base::byte_vector _passwordHashForAuth;
-	base::byte_vector _secret;
+	bytes::vector _passwordHashForSecret;
+	bytes::vector _passwordHashForAuth;
+	bytes::vector _secret;
 	std::vector<base::lambda<void()>> _secretCallbacks;
 	mtpRequestId _saveSecretRequestId = 0;
 	QString _passwordEmail;
diff --git a/Telegram/SourceFiles/storage/file_download.cpp b/Telegram/SourceFiles/storage/file_download.cpp
index d1b67bb36..7388e6333 100644
--- a/Telegram/SourceFiles/storage/file_download.cpp
+++ b/Telegram/SourceFiles/storage/file_download.cpp
@@ -15,6 +15,8 @@ https://github.com/telegramdesktop/tdesktop/blob/master/LEGAL
 #include "platform/platform_file_utilities.h"
 #include "auth_session.h"
 #include "core/crash_reports.h"
+#include "base/bytes.h"
+#include "base/openssl_help.h"
 
 namespace Storage {
 
@@ -530,8 +532,8 @@ void mtpFileLoader::normalPartLoaded(const MTPupload_File &result, mtpRequestId
 	if (result.type() == mtpc_upload_fileCdnRedirect) {
 		return switchToCDN(offset, result.c_upload_fileCdnRedirect());
 	}
-	auto bytes = gsl::as_bytes(gsl::make_span(result.c_upload_file().vbytes.v));
-	return partLoaded(offset, bytes);
+	auto buffer = bytes::make_span(result.c_upload_file().vbytes.v);
+	return partLoaded(offset, buffer);
 }
 
 void mtpFileLoader::webPartLoaded(const MTPupload_WebFile &result, mtpRequestId requestId) {
@@ -545,8 +547,8 @@ void mtpFileLoader::webPartLoaded(const MTPupload_WebFile &result, mtpRequestId
 		LOG(("MTP Error: Bad size provided by bot for webDocument: %1, real: %2").arg(_size).arg(webFile.vsize.v));
 		return cancel(true);
 	}
-	auto bytes = gsl::as_bytes(gsl::make_span(webFile.vbytes.v));
-	return partLoaded(offset, bytes);
+	auto buffer = bytes::make_span(webFile.vbytes.v);
+	return partLoaded(offset, buffer);
 }
 
 void mtpFileLoader::cdnPartLoaded(const MTPupload_CdnFile &result, mtpRequestId requestId) {
@@ -565,13 +567,13 @@ void mtpFileLoader::cdnPartLoaded(const MTPupload_CdnFile &result, mtpRequestId
 	}
 	Expects(result.type() == mtpc_upload_cdnFile);
 
-	auto key = gsl::as_bytes(gsl::make_span(_cdnEncryptionKey));
-	auto iv = gsl::as_bytes(gsl::make_span(_cdnEncryptionIV));
+	auto key = bytes::make_span(_cdnEncryptionKey);
+	auto iv = bytes::make_span(_cdnEncryptionIV);
 	Expects(key.size() == MTP::CTRState::KeySize);
 	Expects(iv.size() == MTP::CTRState::IvecSize);
 
 	auto state = MTP::CTRState();
-	auto ivec = gsl::as_writeable_bytes(gsl::make_span(state.ivec));
+	auto ivec = bytes::make_span(state.ivec);
 	std::copy(iv.begin(), iv.end(), ivec.begin());
 
 	auto counterOffset = static_cast<uint32>(offset) >> 4;
@@ -582,9 +584,9 @@ void mtpFileLoader::cdnPartLoaded(const MTPupload_CdnFile &result, mtpRequestId
 
 	auto decryptInPlace = result.c_upload_cdnFile().vbytes.v;
 	MTP::aesCtrEncrypt(decryptInPlace.data(), decryptInPlace.size(), key.data(), &state);
-	auto bytes = gsl::as_bytes(gsl::make_span(decryptInPlace));
+	auto buffer = bytes::make_span(decryptInPlace);
 
-	switch (checkCdnFileHash(offset, bytes)) {
+	switch (checkCdnFileHash(offset, buffer)) {
 	case CheckCdnHashResult::NoHash: {
 		_cdnUncheckedParts.emplace(offset, decryptInPlace);
 		requestMoreCdnFileHashes();
@@ -595,18 +597,18 @@ void mtpFileLoader::cdnPartLoaded(const MTPupload_CdnFile &result, mtpRequestId
 		cancel(true);
 	} return;
 
-	case CheckCdnHashResult::Good: return partLoaded(offset, bytes);
+	case CheckCdnHashResult::Good: return partLoaded(offset, buffer);
 	}
 	Unexpected("Result of checkCdnFileHash()");
 }
 
-mtpFileLoader::CheckCdnHashResult mtpFileLoader::checkCdnFileHash(int offset, base::const_byte_span bytes) {
+mtpFileLoader::CheckCdnHashResult mtpFileLoader::checkCdnFileHash(int offset, bytes::const_span buffer) {
 	auto cdnFileHashIt = _cdnFileHashes.find(offset);
 	if (cdnFileHashIt == _cdnFileHashes.cend()) {
 		return CheckCdnHashResult::NoHash;
 	}
-	auto realHash = hashSha256(bytes.data(), bytes.size());
-	if (base::compare_bytes(gsl::as_bytes(gsl::make_span(realHash)), gsl::as_bytes(gsl::make_span(cdnFileHashIt->second.hash)))) {
+	auto realHash = openssl::Sha256(buffer);
+	if (bytes::compare(realHash, bytes::make_span(cdnFileHashIt->second.hash))) {
 		return CheckCdnHashResult::Invalid;
 	}
 	return CheckCdnHashResult::Good;
@@ -629,7 +631,7 @@ void mtpFileLoader::getCdnFileHashesDone(const MTPVector<MTPFileHash> &result, m
 	auto someMoreChecked = false;
 	for (auto i = _cdnUncheckedParts.begin(); i != _cdnUncheckedParts.cend();) {
 		const auto uncheckedOffset = i->first;
-		const auto uncheckedBytes = gsl::as_bytes(gsl::make_span(i->second));
+		const auto uncheckedBytes = bytes::make_span(i->second);
 
 		switch (checkCdnFileHash(uncheckedOffset, uncheckedBytes)) {
 		case CheckCdnHashResult::NoHash: {
@@ -646,10 +648,9 @@ void mtpFileLoader::getCdnFileHashesDone(const MTPVector<MTPFileHash> &result, m
 			someMoreChecked = true;
 			const auto goodOffset = uncheckedOffset;
 			const auto goodBytes = std::move(i->second);
-			const auto goodBytesSpan = gsl::make_span(goodBytes);
 			const auto weak = QPointer<mtpFileLoader>(this);
 			i = _cdnUncheckedParts.erase(i);
-			if (!feedPart(goodOffset, gsl::as_bytes(goodBytesSpan))
+			if (!feedPart(goodOffset, bytes::make_span(goodBytes))
 				|| !weak) {
 				return;
 			} else if (_finished) {
@@ -692,30 +693,30 @@ int mtpFileLoader::finishSentRequestGetOffset(mtpRequestId requestId) {
 	return requestData.offset;
 }
 
-bool mtpFileLoader::feedPart(int offset, base::const_byte_span bytes) {
+bool mtpFileLoader::feedPart(int offset, bytes::const_span buffer) {
 	Expects(!_finished);
 
-	if (bytes.size()) {
+	if (buffer.size()) {
 		if (_fileIsOpen) {
 			auto fsize = _file.size();
 			if (offset < fsize) {
-				_skippedBytes -= bytes.size();
+				_skippedBytes -= buffer.size();
 			} else if (offset > fsize) {
 				_skippedBytes += offset - fsize;
 			}
 			_file.seek(offset);
-			if (_file.write(reinterpret_cast<const char*>(bytes.data()), bytes.size()) != qint64(bytes.size())) {
+			if (_file.write(reinterpret_cast<const char*>(buffer.data()), buffer.size()) != qint64(buffer.size())) {
 				cancel(true);
 				return false;
 			}
 		} else {
 			if (offset > 100 * 1024 * 1024) {
 				// Debugging weird out of memory crashes.
-				auto info = QString("offset: %1, size: %2, cancelled: %3, finished: %4, filename: '%5', tocache: %6, fromcloud: %7, data: %8, fullsize: %9").arg(offset).arg(bytes.size()).arg(Logs::b(_cancelled)).arg(Logs::b(_finished)).arg(_filename).arg(int(_toCache)).arg(int(_fromCloud)).arg(_data.size()).arg(_size);
+				auto info = QString("offset: %1, size: %2, cancelled: %3, finished: %4, filename: '%5', tocache: %6, fromcloud: %7, data: %8, fullsize: %9").arg(offset).arg(buffer.size()).arg(Logs::b(_cancelled)).arg(Logs::b(_finished)).arg(_filename).arg(int(_toCache)).arg(int(_fromCloud)).arg(_data.size()).arg(_size);
 				info += QString(", locationtype: %1, inqueue: %2, localstatus: %3").arg(int(_locationType)).arg(Logs::b(_inQueue)).arg(int(_localStatus));
 				CrashReports::SetAnnotation("DebugInfo", info);
 			}
-			_data.reserve(offset + bytes.size());
+			_data.reserve(offset + buffer.size());
 			if (offset > 100 * 1024 * 1024) {
 				CrashReports::ClearAnnotation("DebugInfo");
 			}
@@ -725,19 +726,18 @@ bool mtpFileLoader::feedPart(int offset, base::const_byte_span bytes) {
 				_data.resize(offset);
 			}
 			if (offset == _data.size()) {
-				_data.append(reinterpret_cast<const char*>(bytes.data()), bytes.size());
+				_data.append(reinterpret_cast<const char*>(buffer.data()), buffer.size());
 			} else {
-				_skippedBytes -= bytes.size();
-				if (int64(offset + bytes.size()) > _data.size()) {
-					_data.resize(offset + bytes.size());
+				_skippedBytes -= buffer.size();
+				if (int64(offset + buffer.size()) > _data.size()) {
+					_data.resize(offset + buffer.size());
 				}
-				auto src = bytes;
-				auto dst = gsl::make_span(_data).subspan(offset, bytes.size());
-				base::copy_bytes(gsl::as_writeable_bytes(dst), src);
+				auto dst = bytes::make_span(_data).subspan(offset, buffer.size());
+				bytes::copy(dst, buffer);
 			}
 		}
 	}
-	if (!bytes.size() || (bytes.size() % 1024)) { // bad next offset
+	if (!buffer.size() || (buffer.size() % 1024)) { // bad next offset
 		_lastComplete = true;
 	}
 	if (_sentRequests.empty()
@@ -786,8 +786,8 @@ bool mtpFileLoader::feedPart(int offset, base::const_byte_span bytes) {
 	return true;
 }
 
-void mtpFileLoader::partLoaded(int offset, base::const_byte_span bytes) {
-	if (feedPart(offset, bytes)) {
+void mtpFileLoader::partLoaded(int offset, bytes::const_span buffer) {
+	if (feedPart(offset, buffer)) {
 		emit progress(this);
 		loadNext();
 	}
diff --git a/Telegram/SourceFiles/storage/file_download.h b/Telegram/SourceFiles/storage/file_download.h
index 21f5909ba..5c6673f6b 100644
--- a/Telegram/SourceFiles/storage/file_download.h
+++ b/Telegram/SourceFiles/storage/file_download.h
@@ -226,8 +226,8 @@ private:
 	void requestMoreCdnFileHashes();
 	void getCdnFileHashesDone(const MTPVector<MTPFileHash> &result, mtpRequestId requestId);
 
-	bool feedPart(int offset, base::const_byte_span bytes);
-	void partLoaded(int offset, base::const_byte_span bytes);
+	bool feedPart(int offset, bytes::const_span buffer);
+	void partLoaded(int offset, bytes::const_span buffer);
 
 	bool partFailed(const RPCError &error);
 	bool cdnPartFailed(const RPCError &error, mtpRequestId requestId);
@@ -243,7 +243,7 @@ private:
 		Invalid,
 		Good,
 	};
-	CheckCdnHashResult checkCdnFileHash(int offset, base::const_byte_span bytes);
+	CheckCdnHashResult checkCdnFileHash(int offset, bytes::const_span buffer);
 
 	std::map<mtpRequestId, RequestData> _sentRequests;
 
diff --git a/Telegram/SourceFiles/storage/serialize_common.h b/Telegram/SourceFiles/storage/serialize_common.h
index 7dc7403d0..4a363a5ad 100644
--- a/Telegram/SourceFiles/storage/serialize_common.h
+++ b/Telegram/SourceFiles/storage/serialize_common.h
@@ -20,15 +20,15 @@ inline int bytearraySize(const QByteArray &arr) {
 	return sizeof(quint32) + arr.size();
 }
 
-inline int bytesSize(base::const_byte_span bytes) {
+inline int bytesSize(bytes::const_span bytes) {
 	return sizeof(quint32) + bytes.size();
 }
 
 struct ReadBytesVectorWrap {
-	base::byte_vector &bytes;
+	bytes::vector &bytes;
 };
 
-inline ReadBytesVectorWrap bytes(base::byte_vector &bytes) {
+inline ReadBytesVectorWrap bytes(bytes::vector &bytes) {
 	return ReadBytesVectorWrap { bytes };
 }
 
@@ -58,10 +58,10 @@ inline QDataStream &operator>>(QDataStream &stream, ReadBytesVectorWrap data) {
 }
 
 struct WriteBytesWrap {
-	base::const_byte_span bytes;
+	bytes::const_span bytes;
 };
 
-inline WriteBytesWrap bytes(base::const_byte_span bytes) {
+inline WriteBytesWrap bytes(bytes::const_span bytes) {
 	return WriteBytesWrap { bytes };
 }