Merge branch 'master' into notsure2

internal/multiplex/obfs.go

@@ -11,9 +11,6 @@ import (
 	"golang.org/x/crypto/salsa20"
 )
 
-type Obfser func(*Frame, []byte, int) (int, error)
-type Deobfser func(*Frame, []byte) error
-
 const frameHeaderLength = 14
 const salsa20NonceSize = 8
 
@@ -26,25 +23,19 @@ const (
 
 // Obfuscator is responsible for serialisation, obfuscation, and optional encryption of data frames.
 type Obfuscator struct {
-	// Used in Stream.Write. Add multiplexing headers, encrypt and add TLS header
+	payloadCipher cipher.AEAD
-	Obfs Obfser
+
-	// Remove TLS header, decrypt and unmarshall frames
+	sessionKey [32]byte
-	Deobfs     Deobfser
-	SessionKey [32]byte
 
 	maxOverhead int
 }
 
-// MakeObfs returns a function of type Obfser. An Obfser takes three arguments:
+// obfuscate adds multiplexing headers, encrypt and add TLS header
-// a *Frame with all the field set correctly, a []byte as buffer to put encrypted
+func (o *Obfuscator) obfuscate(f *Frame, buf []byte, payloadOffsetInBuf int) (int, error) {
-// message in, and an int called payloadOffsetInBuf to be used when *Frame.payload
-// is in the byte slice used as buffer (2nd argument). payloadOffsetInBuf specifies
-// the index at which data belonging to *Frame.Payload starts in the buffer.
-func MakeObfs(salsaKey [32]byte, payloadCipher cipher.AEAD) Obfser {
 	// The method here is to use the first payloadCipher.NonceSize() bytes of the serialised frame header
 	// as iv/nonce for the AEAD cipher to encrypt the frame payload. Then we use
 	// the authentication tag produced appended to the end of the ciphertext (of size payloadCipher.Overhead())
-	// as nonce for Salsa20 to encrypt the frame header. Both with SessionKey as keys.
+	// as nonce for Salsa20 to encrypt the frame header. Both with sessionKey as keys.
 	//
 	// Several cryptographic guarantees we have made here: that payloadCipher, as an AEAD, is given a unique
 	// iv/nonce each time, relative to its key; that the frame header encryptor Salsa20 is given a unique
@@ -72,159 +63,146 @@ func MakeObfs(salsaKey [32]byte, payloadCipher cipher.AEAD) Obfser {
 	// We can't ensure its uniqueness ourselves, which is why plaintext mode must only be used when the user input
 	// is already random-like. For Cloak it would normally mean that the user is using a proxy protocol that sends
 	// encrypted data.
-	obfs := func(f *Frame, buf []byte, payloadOffsetInBuf int) (int, error) {
+	payloadLen := len(f.Payload)
-		payloadLen := len(f.Payload)
+	if payloadLen == 0 {
-		if payloadLen == 0 {
+		return 0, errors.New("payload cannot be empty")
-			return 0, errors.New("payload cannot be empty")
-		}
-		var extraLen int
-		if payloadCipher == nil {
-			extraLen = salsa20NonceSize - payloadLen
-			if extraLen < 0 {
-				// if our payload is already greater than 8 bytes
-				extraLen = 0
-			}
-		} else {
-			extraLen = payloadCipher.Overhead()
-			if extraLen < salsa20NonceSize {
-				return 0, errors.New("AEAD's Overhead cannot be fewer than 8 bytes")
-			}
-		}
-
-		usefulLen := frameHeaderLength + payloadLen + extraLen
-		if len(buf) < usefulLen {
-			return 0, errors.New("obfs buffer too small")
-		}
-		// we do as much in-place as possible to save allocation
-		payload := buf[frameHeaderLength : frameHeaderLength+payloadLen]
-		if payloadOffsetInBuf != frameHeaderLength {
-			// if payload is not at the correct location in buffer
-			copy(payload, f.Payload)
-		}
-
-		header := buf[:frameHeaderLength]
-		binary.BigEndian.PutUint32(header[0:4], f.StreamID)
-		binary.BigEndian.PutUint64(header[4:12], f.Seq)
-		header[12] = f.Closing
-		header[13] = byte(extraLen)
-
-		if payloadCipher == nil {
-			if extraLen != 0 { // read nonce
-				extra := buf[usefulLen-extraLen : usefulLen]
-				common.CryptoRandRead(extra)
-			}
-		} else {
-			payloadCipher.Seal(payload[:0], header[:payloadCipher.NonceSize()], payload, nil)
-		}
-
-		nonce := buf[usefulLen-salsa20NonceSize : usefulLen]
-		salsa20.XORKeyStream(header, header, nonce, &salsaKey)
-
-		return usefulLen, nil
 	}
-	return obfs
+	var extraLen int
+	if o.payloadCipher == nil {
+		extraLen = salsa20NonceSize - payloadLen
+		if extraLen < 0 {
+			// if our payload is already greater than 8 bytes
+			extraLen = 0
+		}
+	} else {
+		extraLen = o.payloadCipher.Overhead()
+		if extraLen < salsa20NonceSize {
+			return 0, errors.New("AEAD's Overhead cannot be fewer than 8 bytes")
+		}
+	}
+
+	usefulLen := frameHeaderLength + payloadLen + extraLen
+	if len(buf) < usefulLen {
+		return 0, errors.New("obfs buffer too small")
+	}
+	// we do as much in-place as possible to save allocation
+	payload := buf[frameHeaderLength : frameHeaderLength+payloadLen]
+	if payloadOffsetInBuf != frameHeaderLength {
+		// if payload is not at the correct location in buffer
+		copy(payload, f.Payload)
+	}
+
+	header := buf[:frameHeaderLength]
+	binary.BigEndian.PutUint32(header[0:4], f.StreamID)
+	binary.BigEndian.PutUint64(header[4:12], f.Seq)
+	header[12] = f.Closing
+	header[13] = byte(extraLen)
+
+	if o.payloadCipher == nil {
+		if extraLen != 0 { // read nonce
+			extra := buf[usefulLen-extraLen : usefulLen]
+			common.CryptoRandRead(extra)
+		}
+	} else {
+		o.payloadCipher.Seal(payload[:0], header[:o.payloadCipher.NonceSize()], payload, nil)
+	}
+
+	nonce := buf[usefulLen-salsa20NonceSize : usefulLen]
+	salsa20.XORKeyStream(header, header, nonce, &o.sessionKey)
+
+	return usefulLen, nil
 }
 
-// MakeDeobfs returns a function Deobfser. A Deobfser takes in a single byte slice,
+// deobfuscate removes TLS header, decrypt and unmarshall frames
-// containing the message to be decrypted, and returns a *Frame containing the frame
+func (o *Obfuscator) deobfuscate(f *Frame, in []byte) error {
-// information and plaintext
+	if len(in) < frameHeaderLength+salsa20NonceSize {
-func MakeDeobfs(salsaKey [32]byte, payloadCipher cipher.AEAD) Deobfser {
+		return fmt.Errorf("input size %v, but it cannot be shorter than %v bytes", len(in), frameHeaderLength+salsa20NonceSize)
-	// frame header length + minimum data size (i.e. nonce size of salsa20)
+	}
-	const minInputLen = frameHeaderLength + salsa20NonceSize
-	deobfs := func(f *Frame, in []byte) error {
-		if len(in) < minInputLen {
-			return fmt.Errorf("input size %v, but it cannot be shorter than %v bytes", len(in), minInputLen)
-		}
 
-		header := in[:frameHeaderLength]
+	header := in[:frameHeaderLength]
-		pldWithOverHead := in[frameHeaderLength:] // payload + potential overhead
+	pldWithOverHead := in[frameHeaderLength:] // payload + potential overhead
 
-		nonce := in[len(in)-salsa20NonceSize:]
+	nonce := in[len(in)-salsa20NonceSize:]
-		salsa20.XORKeyStream(header, header, nonce, &salsaKey)
+	salsa20.XORKeyStream(header, header, nonce, &o.sessionKey)
 
-		streamID := binary.BigEndian.Uint32(header[0:4])
+	streamID := binary.BigEndian.Uint32(header[0:4])
-		seq := binary.BigEndian.Uint64(header[4:12])
+	seq := binary.BigEndian.Uint64(header[4:12])
-		closing := header[12]
+	closing := header[12]
-		extraLen := header[13]
+	extraLen := header[13]
 
-		usefulPayloadLen := len(pldWithOverHead) - int(extraLen)
+	usefulPayloadLen := len(pldWithOverHead) - int(extraLen)
-		if usefulPayloadLen < 0 || usefulPayloadLen > len(pldWithOverHead) {
+	if usefulPayloadLen < 0 || usefulPayloadLen > len(pldWithOverHead) {
-			return errors.New("extra length is negative or extra length is greater than total pldWithOverHead length")
+		return errors.New("extra length is negative or extra length is greater than total pldWithOverHead length")
-		}
+	}
 
-		var outputPayload []byte
+	var outputPayload []byte
 
-		if payloadCipher == nil {
+	if o.payloadCipher == nil {
-			if extraLen == 0 {
+		if extraLen == 0 {
-				outputPayload = pldWithOverHead
+			outputPayload = pldWithOverHead
-			} else {
-				outputPayload = pldWithOverHead[:usefulPayloadLen]
-			}
 		} else {
-			_, err := payloadCipher.Open(pldWithOverHead[:0], header[:payloadCipher.NonceSize()], pldWithOverHead, nil)
-			if err != nil {
-				return err
-			}
 			outputPayload = pldWithOverHead[:usefulPayloadLen]
 		}
-
+	} else {
-		f.StreamID = streamID
+		_, err := o.payloadCipher.Open(pldWithOverHead[:0], header[:o.payloadCipher.NonceSize()], pldWithOverHead, nil)
-		f.Seq = seq
+		if err != nil {
-		f.Closing = closing
+			return err
-		f.Payload = outputPayload
+		}
-		return nil
+		outputPayload = pldWithOverHead[:usefulPayloadLen]
 	}
-	return deobfs
+
+	f.StreamID = streamID
+	f.Seq = seq
+	f.Closing = closing
+	f.Payload = outputPayload
+	return nil
 }
 
-func MakeObfuscator(encryptionMethod byte, sessionKey [32]byte) (obfuscator Obfuscator, err error) {
+func MakeObfuscator(encryptionMethod byte, sessionKey [32]byte) (o Obfuscator, err error) {
-	obfuscator = Obfuscator{
+	o = Obfuscator{
-		SessionKey: sessionKey,
+		sessionKey: sessionKey,
 	}
-	var payloadCipher cipher.AEAD
 	switch encryptionMethod {
 	case EncryptionMethodPlain:
-		payloadCipher = nil
+		o.payloadCipher = nil
-		obfuscator.maxOverhead = salsa20NonceSize
+		o.maxOverhead = salsa20NonceSize
 	case EncryptionMethodAES256GCM:
 		var c cipher.Block
 		c, err = aes.NewCipher(sessionKey[:])
 		if err != nil {
 			return
 		}
-		payloadCipher, err = cipher.NewGCM(c)
+		o.payloadCipher, err = cipher.NewGCM(c)
 		if err != nil {
 			return
 		}
-		obfuscator.maxOverhead = payloadCipher.Overhead()
+		o.maxOverhead = o.payloadCipher.Overhead()
 	case EncryptionMethodAES128GCM:
 		var c cipher.Block
 		c, err = aes.NewCipher(sessionKey[:16])
 		if err != nil {
 			return
 		}
-		payloadCipher, err = cipher.NewGCM(c)
+		o.payloadCipher, err = cipher.NewGCM(c)
 		if err != nil {
 			return
 		}
-		obfuscator.maxOverhead = payloadCipher.Overhead()
+		o.maxOverhead = o.payloadCipher.Overhead()
 	case EncryptionMethodChaha20Poly1305:
-		payloadCipher, err = chacha20poly1305.New(sessionKey[:])
+		o.payloadCipher, err = chacha20poly1305.New(sessionKey[:])
 		if err != nil {
 			return
 		}
-		obfuscator.maxOverhead = payloadCipher.Overhead()
+		o.maxOverhead = o.payloadCipher.Overhead()
 	default:
-		return obfuscator, errors.New("Unknown encryption method")
+		return o, fmt.Errorf("unknown encryption method valued %v", encryptionMethod)
 	}
 
-	if payloadCipher != nil {
+	if o.payloadCipher != nil {
-		if payloadCipher.NonceSize() > frameHeaderLength {
+		if o.payloadCipher.NonceSize() > frameHeaderLength {
-			return obfuscator, errors.New("payload AEAD's nonce size cannot be greater than size of frame header")
+			return o, errors.New("payload AEAD's nonce size cannot be greater than size of frame header")
 		}
 	}
 
-	obfuscator.Obfs = MakeObfs(sessionKey, payloadCipher)
-	obfuscator.Deobfs = MakeDeobfs(sessionKey, payloadCipher)
 	return
 }

internal/multiplex/obfs_test.go

@@ -1,9 +1,9 @@
 package multiplex
 
 import (
-	"bytes"
 	"crypto/aes"
 	"crypto/cipher"
+	"github.com/stretchr/testify/assert"
 	"golang.org/x/crypto/chacha20poly1305"
 	"math/rand"
 	"reflect"
@@ -15,69 +15,119 @@ func TestGenerateObfs(t *testing.T) {
 	var sessionKey [32]byte
 	rand.Read(sessionKey[:])
 
-	run := func(obfuscator Obfuscator, ct *testing.T) {
+	run := func(o Obfuscator, t *testing.T) {
 		obfsBuf := make([]byte, 512)
-		_testFrame, _ := quick.Value(reflect.TypeOf(&Frame{}), rand.New(rand.NewSource(42)))
+		_testFrame, _ := quick.Value(reflect.TypeOf(Frame{}), rand.New(rand.NewSource(42)))
-		testFrame := _testFrame.Interface().(*Frame)
+		testFrame := _testFrame.Interface().(Frame)
-		i, err := obfuscator.Obfs(testFrame, obfsBuf, 0)
+		i, err := o.obfuscate(&testFrame, obfsBuf, 0)
-		if err != nil {
+		assert.NoError(t, err)
-			ct.Error("failed to obfs ", err)
-			return
-		}
-
 		var resultFrame Frame
-		err = obfuscator.Deobfs(&resultFrame, obfsBuf[:i])
+
-		if err != nil {
+		err = o.deobfuscate(&resultFrame, obfsBuf[:i])
-			ct.Error("failed to deobfs ", err)
+		assert.NoError(t, err)
-			return
+		assert.EqualValues(t, testFrame, resultFrame)
-		}
-		if !bytes.Equal(testFrame.Payload, resultFrame.Payload) || testFrame.StreamID != resultFrame.StreamID {
-			ct.Error("expecting", testFrame,
-				"got", resultFrame)
-			return
-		}
 	}
 
 	t.Run("plain", func(t *testing.T) {
-		obfuscator, err := MakeObfuscator(EncryptionMethodPlain, sessionKey)
+		o, err := MakeObfuscator(EncryptionMethodPlain, sessionKey)
-		if err != nil {
+		assert.NoError(t, err)
-			t.Errorf("failed to generate obfuscator %v", err)
+		run(o, t)
-		} else {
-			run(obfuscator, t)
-		}
 	})
 	t.Run("aes-256-gcm", func(t *testing.T) {
-		obfuscator, err := MakeObfuscator(EncryptionMethodAES256GCM, sessionKey)
+		o, err := MakeObfuscator(EncryptionMethodAES256GCM, sessionKey)
-		if err != nil {
+		assert.NoError(t, err)
-			t.Errorf("failed to generate obfuscator %v", err)
+		run(o, t)
-		} else {
-			run(obfuscator, t)
-		}
 	})
 	t.Run("aes-128-gcm", func(t *testing.T) {
-		obfuscator, err := MakeObfuscator(EncryptionMethodAES128GCM, sessionKey)
+		o, err := MakeObfuscator(EncryptionMethodAES128GCM, sessionKey)
-		if err != nil {
+		assert.NoError(t, err)
-			t.Errorf("failed to generate obfuscator %v", err)
+		run(o, t)
-		} else {
-			run(obfuscator, t)
-		}
 	})
 	t.Run("chacha20-poly1305", func(t *testing.T) {
-		obfuscator, err := MakeObfuscator(EncryptionMethodChaha20Poly1305, sessionKey)
+		o, err := MakeObfuscator(EncryptionMethodChaha20Poly1305, sessionKey)
-		if err != nil {
+		assert.NoError(t, err)
-			t.Errorf("failed to generate obfuscator %v", err)
+		run(o, t)
-		} else {
-			run(obfuscator, t)
-		}
 	})
 	t.Run("unknown encryption method", func(t *testing.T) {
 		_, err := MakeObfuscator(0xff, sessionKey)
-		if err == nil {
+		assert.Error(t, err)
-			t.Errorf("unknown encryption mehtod error expected")
-		}
 	})
 }
 
+func TestObfuscate(t *testing.T) {
+	var sessionKey [32]byte
+	rand.Read(sessionKey[:])
+
+	const testPayloadLen = 1024
+	testPayload := make([]byte, testPayloadLen)
+	rand.Read(testPayload)
+	f := Frame{
+		StreamID: 0,
+		Seq:      0,
+		Closing:  0,
+		Payload:  testPayload,
+	}
+
+	runTest := func(t *testing.T, o Obfuscator) {
+		obfsBuf := make([]byte, testPayloadLen*2)
+		n, err := o.obfuscate(&f, obfsBuf, 0)
+		assert.NoError(t, err)
+
+		resultFrame := Frame{}
+		err = o.deobfuscate(&resultFrame, obfsBuf[:n])
+		assert.NoError(t, err)
+
+		assert.EqualValues(t, f, resultFrame)
+	}
+
+	t.Run("plain", func(t *testing.T) {
+		o := Obfuscator{
+			payloadCipher: nil,
+			sessionKey:    sessionKey,
+			maxOverhead:   salsa20NonceSize,
+		}
+		runTest(t, o)
+	})
+
+	t.Run("aes-128-gcm", func(t *testing.T) {
+		c, err := aes.NewCipher(sessionKey[:16])
+		assert.NoError(t, err)
+		payloadCipher, err := cipher.NewGCM(c)
+		assert.NoError(t, err)
+		o := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    sessionKey,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
+		runTest(t, o)
+	})
+
+	t.Run("aes-256-gcm", func(t *testing.T) {
+		c, err := aes.NewCipher(sessionKey[:])
+		assert.NoError(t, err)
+		payloadCipher, err := cipher.NewGCM(c)
+		assert.NoError(t, err)
+		o := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    sessionKey,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
+		runTest(t, o)
+	})
+
+	t.Run("chacha20-poly1305", func(t *testing.T) {
+		payloadCipher, err := chacha20poly1305.New(sessionKey[:])
+		assert.NoError(t, err)
+		o := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    sessionKey,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
+		runTest(t, o)
+	})
+
+}
+
 func BenchmarkObfs(b *testing.B) {
 	testPayload := make([]byte, 1024)
 	rand.Read(testPayload)
@@ -96,40 +146,57 @@ func BenchmarkObfs(b *testing.B) {
 		c, _ := aes.NewCipher(key[:])
 		payloadCipher, _ := cipher.NewGCM(c)
 
-		obfs := MakeObfs(key, payloadCipher)
+		obfuscator := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    key,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
+
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			obfs(testFrame, obfsBuf, 0)
+			obfuscator.obfuscate(testFrame, obfsBuf, 0)
 		}
 	})
 	b.Run("AES128GCM", func(b *testing.B) {
 		c, _ := aes.NewCipher(key[:16])
 		payloadCipher, _ := cipher.NewGCM(c)
 
-		obfs := MakeObfs(key, payloadCipher)
+		obfuscator := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    key,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			obfs(testFrame, obfsBuf, 0)
+			obfuscator.obfuscate(testFrame, obfsBuf, 0)
 		}
 	})
 	b.Run("plain", func(b *testing.B) {
-		obfs := MakeObfs(key, nil)
+		obfuscator := Obfuscator{
+			payloadCipher: nil,
+			sessionKey:    key,
+			maxOverhead:   salsa20NonceSize,
+		}
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			obfs(testFrame, obfsBuf, 0)
+			obfuscator.obfuscate(testFrame, obfsBuf, 0)
 		}
 	})
 	b.Run("chacha20Poly1305", func(b *testing.B) {
-		payloadCipher, _ := chacha20poly1305.New(key[:16])
+		payloadCipher, _ := chacha20poly1305.New(key[:])
 
-		obfs := MakeObfs(key, payloadCipher)
+		obfuscator := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    key,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
 		b.SetBytes(int64(len(testFrame.Payload)))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			obfs(testFrame, obfsBuf, 0)
+			obfuscator.obfuscate(testFrame, obfsBuf, 0)
 		}
 	})
 }
@@ -151,57 +218,70 @@ func BenchmarkDeobfs(b *testing.B) {
 	b.Run("AES256GCM", func(b *testing.B) {
 		c, _ := aes.NewCipher(key[:])
 		payloadCipher, _ := cipher.NewGCM(c)
+		obfuscator := Obfuscator{
+			payloadCipher: payloadCipher,
+			sessionKey:    key,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
 
-		obfs := MakeObfs(key, payloadCipher)
+		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
-		n, _ := obfs(testFrame, obfsBuf, 0)
-		deobfs := MakeDeobfs(key, payloadCipher)
 
 		frame := new(Frame)
 		b.SetBytes(int64(n))
 		b.ResetTimer()
 		for i := 0; i < b.N; i++ {
-			deobfs(frame, obfsBuf[:n])
+			obfuscator.deobfuscate(frame, obfsBuf[:n])
 		}
 	})
 	b.Run("AES128GCM", func(b *testing.B) {
 		c, _ := aes.NewCipher(key[:16])
 		payloadCipher, _ := cipher.NewGCM(c)
 
-		obfs := MakeObfs(key, payloadCipher)
+		obfuscator := Obfuscator{
-		n, _ := obfs(testFrame, obfsBuf, 0)
+			payloadCipher: payloadCipher,
-		deobfs := MakeDeobfs(key, payloadCipher)
+			sessionKey:    key,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
+		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
 
 		frame := new(Frame)
 		b.ResetTimer()
 		b.SetBytes(int64(n))
 		for i := 0; i < b.N; i++ {
-			deobfs(frame, obfsBuf[:n])
+			obfuscator.deobfuscate(frame, obfsBuf[:n])
 		}
 	})
 	b.Run("plain", func(b *testing.B) {
-		obfs := MakeObfs(key, nil)
+		obfuscator := Obfuscator{
-		n, _ := obfs(testFrame, obfsBuf, 0)
+			payloadCipher: nil,
-		deobfs := MakeDeobfs(key, nil)
+			sessionKey:    key,
+			maxOverhead:   salsa20NonceSize,
+		}
+		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
 
 		frame := new(Frame)
 		b.ResetTimer()
 		b.SetBytes(int64(n))
 		for i := 0; i < b.N; i++ {
-			deobfs(frame, obfsBuf[:n])
+			obfuscator.deobfuscate(frame, obfsBuf[:n])
 		}
 	})
 	b.Run("chacha20Poly1305", func(b *testing.B) {
-		payloadCipher, _ := chacha20poly1305.New(key[:16])
+		payloadCipher, _ := chacha20poly1305.New(key[:])
 
-		obfs := MakeObfs(key, payloadCipher)
+		obfuscator := Obfuscator{
-		n, _ := obfs(testFrame, obfsBuf, 0)
+			payloadCipher: nil,
-		deobfs := MakeDeobfs(key, payloadCipher)
+			sessionKey:    key,
+			maxOverhead:   payloadCipher.Overhead(),
+		}
+
+		n, _ := obfuscator.obfuscate(testFrame, obfsBuf, 0)
 
 		frame := new(Frame)
 		b.ResetTimer()
 		b.SetBytes(int64(n))
 		for i := 0; i < b.N; i++ {
-			deobfs(frame, obfsBuf[:n])
+			obfuscator.deobfuscate(frame, obfsBuf[:n])
 		}
 	})
 }

internal/multiplex/session.go

@@ -128,6 +128,10 @@ func MakeSession(id uint32, config SessionConfig) *Session {
 	return sesh
 }
 
+func (sesh *Session) GetSessionKey() [32]byte {
+	return sesh.sessionKey
+}
+
 func (sesh *Session) streamCountIncr() uint32 {
 	return atomic.AddUint32(&sesh.activeStreamCount, 1)
 }
@@ -232,7 +236,7 @@ func (sesh *Session) recvDataFromRemote(data []byte) error {
 	frame := sesh.recvFramePool.Get().(*Frame)
 	defer sesh.recvFramePool.Put(frame)
 
-	err := sesh.Deobfs(frame, data)
+	err := sesh.deobfuscate(frame, data)
 	if err != nil {
 		return fmt.Errorf("Failed to decrypt a frame for session %v: %v", sesh.id, err)
 	}
@@ -331,7 +335,7 @@ func (sesh *Session) Close() error {
 		Closing:  closingSession,
 		Payload:  payload,
 	}
-	i, err := sesh.Obfs(f, *buf, frameHeaderLength)
+	i, err := sesh.obfuscate(f, *buf, frameHeaderLength)
 	if err != nil {
 		return err
 	}

internal/multiplex/session_test.go

@@ -4,7 +4,10 @@ import (
 	"bytes"
 	"github.com/cbeuw/connutil"
 	"github.com/stretchr/testify/assert"
+	"io"
+	"io/ioutil"
 	"math/rand"
+	"net"
 	"strconv"
 	"sync"
 	"sync/atomic"
@@ -16,73 +19,188 @@ var seshConfigs = map[string]SessionConfig{
 	"ordered":   {},
 	"unordered": {Unordered: true},
 }
+var encryptionMethods = map[string]byte{
+	"plain":            EncryptionMethodPlain,
+	"aes-256-gcm":      EncryptionMethodAES256GCM,
+	"aes-128-gcm":      EncryptionMethodAES128GCM,
+	"chacha20poly1305": EncryptionMethodChaha20Poly1305,
+}
 
 const testPayloadLen = 1024
 const obfsBufLen = testPayloadLen * 2
 
 func TestRecvDataFromRemote(t *testing.T) {
-	testPayload := make([]byte, testPayloadLen)
-	rand.Read(testPayload)
-	f := &Frame{
-		1,
-		0,
-		0,
-		testPayload,
-	}
-	obfsBuf := make([]byte, obfsBufLen)
-
 	var sessionKey [32]byte
 	rand.Read(sessionKey[:])
 
-	MakeObfuscatorUnwrap := func(method byte, sessionKey [32]byte) Obfuscator {
-		ret, err := MakeObfuscator(method, sessionKey)
-		if err != nil {
-			t.Fatalf("failed to make an obfuscator: %v", err)
-		}
-		return ret
-	}
-
-	encryptionMethods := map[string]Obfuscator{
-		"plain":             MakeObfuscatorUnwrap(EncryptionMethodPlain, sessionKey),
-		"aes-gcm":           MakeObfuscatorUnwrap(EncryptionMethodAES256GCM, sessionKey),
-		"chacha20-poly1305": MakeObfuscatorUnwrap(EncryptionMethodChaha20Poly1305, sessionKey),
-	}
-
 	for seshType, seshConfig := range seshConfigs {
 		seshConfig := seshConfig
 		t.Run(seshType, func(t *testing.T) {
-			for method, obfuscator := range encryptionMethods {
+			var err error
-				obfuscator := obfuscator
+			seshConfig.Obfuscator, err = MakeObfuscator(EncryptionMethodPlain, sessionKey)
-				t.Run(method, func(t *testing.T) {
+			if err != nil {
-					seshConfig.Obfuscator = obfuscator
+				t.Fatalf("failed to make obfuscator: %v", err)
+			}
+			t.Run("initial frame", func(t *testing.T) {
+				sesh := MakeSession(0, seshConfig)
+				obfsBuf := make([]byte, obfsBufLen)
+				f := Frame{
+					1,
+					0,
+					0,
+					make([]byte, testPayloadLen),
+				}
+				rand.Read(f.Payload)
+				n, err := sesh.obfuscate(&f, obfsBuf, 0)
+				assert.NoError(t, err)
+				err = sesh.recvDataFromRemote(obfsBuf[:n])
+				assert.NoError(t, err)
+				stream, err := sesh.Accept()
+				assert.NoError(t, err)
+
+				resultPayload := make([]byte, testPayloadLen)
+				_, err = stream.Read(resultPayload)
+				assert.NoError(t, err)
+
+				assert.EqualValues(t, f.Payload, resultPayload)
+			})
+
+			t.Run("two frames in order", func(t *testing.T) {
+				sesh := MakeSession(0, seshConfig)
+				obfsBuf := make([]byte, obfsBufLen)
+				f := Frame{
+					1,
+					0,
+					0,
+					make([]byte, testPayloadLen),
+				}
+				rand.Read(f.Payload)
+				n, err := sesh.obfuscate(&f, obfsBuf, 0)
+				assert.NoError(t, err)
+				err = sesh.recvDataFromRemote(obfsBuf[:n])
+				assert.NoError(t, err)
+				stream, err := sesh.Accept()
+				assert.NoError(t, err)
+
+				resultPayload := make([]byte, testPayloadLen)
+				_, err = io.ReadFull(stream, resultPayload)
+				assert.NoError(t, err)
+
+				assert.EqualValues(t, f.Payload, resultPayload)
+
+				f.Seq += 1
+				rand.Read(f.Payload)
+				n, err = sesh.obfuscate(&f, obfsBuf, 0)
+				assert.NoError(t, err)
+				err = sesh.recvDataFromRemote(obfsBuf[:n])
+				assert.NoError(t, err)
+
+				_, err = io.ReadFull(stream, resultPayload)
+				assert.NoError(t, err)
+
+				assert.EqualValues(t, f.Payload, resultPayload)
+			})
+
+			t.Run("two frames in order", func(t *testing.T) {
+				sesh := MakeSession(0, seshConfig)
+				obfsBuf := make([]byte, obfsBufLen)
+				f := Frame{
+					1,
+					0,
+					0,
+					make([]byte, testPayloadLen),
+				}
+				rand.Read(f.Payload)
+				n, err := sesh.obfuscate(&f, obfsBuf, 0)
+				assert.NoError(t, err)
+				err = sesh.recvDataFromRemote(obfsBuf[:n])
+				assert.NoError(t, err)
+				stream, err := sesh.Accept()
+				assert.NoError(t, err)
+
+				resultPayload := make([]byte, testPayloadLen)
+				_, err = io.ReadFull(stream, resultPayload)
+				assert.NoError(t, err)
+
+				assert.EqualValues(t, f.Payload, resultPayload)
+
+				f.Seq += 1
+				rand.Read(f.Payload)
+				n, err = sesh.obfuscate(&f, obfsBuf, 0)
+				assert.NoError(t, err)
+				err = sesh.recvDataFromRemote(obfsBuf[:n])
+				assert.NoError(t, err)
+
+				_, err = io.ReadFull(stream, resultPayload)
+				assert.NoError(t, err)
+
+				assert.EqualValues(t, f.Payload, resultPayload)
+			})
+
+			if seshType == "ordered" {
+				t.Run("frames out of order", func(t *testing.T) {
 					sesh := MakeSession(0, seshConfig)
-					n, err := sesh.Obfs(f, obfsBuf, 0)
+					obfsBuf := make([]byte, obfsBufLen)
-					if err != nil {
+					f := Frame{
-						t.Error(err)
+						1,
-						return
+						0,
-					}
+						0,
-					err = sesh.recvDataFromRemote(obfsBuf[:n])
+						nil,
-					if err != nil {
-						t.Error(err)
-						return
-					}
-					stream, err := sesh.Accept()
-					if err != nil {
-						t.Error(err)
-						return
 					}
 
+					// First frame
+					seq0 := make([]byte, testPayloadLen)
+					rand.Read(seq0)
+					f.Seq = 0
+					f.Payload = seq0
+					n, err := sesh.obfuscate(&f, obfsBuf, 0)
+					assert.NoError(t, err)
+					err = sesh.recvDataFromRemote(obfsBuf[:n])
+					assert.NoError(t, err)
+
+					// Third frame
+					seq2 := make([]byte, testPayloadLen)
+					rand.Read(seq2)
+					f.Seq = 2
+					f.Payload = seq2
+					n, err = sesh.obfuscate(&f, obfsBuf, 0)
+					assert.NoError(t, err)
+					err = sesh.recvDataFromRemote(obfsBuf[:n])
+					assert.NoError(t, err)
+
+					// Second frame
+					seq1 := make([]byte, testPayloadLen)
+					rand.Read(seq1)
+					f.Seq = 1
+					f.Payload = seq1
+					n, err = sesh.obfuscate(&f, obfsBuf, 0)
+					assert.NoError(t, err)
+					err = sesh.recvDataFromRemote(obfsBuf[:n])
+					assert.NoError(t, err)
+
+					// Expect things to receive in order
+					stream, err := sesh.Accept()
+					assert.NoError(t, err)
+
 					resultPayload := make([]byte, testPayloadLen)
-					_, err = stream.Read(resultPayload)
+
-					if err != nil {
+					// First
-						t.Error(err)
+					_, err = io.ReadFull(stream, resultPayload)
-						return
+					assert.NoError(t, err)
-					}
+					assert.EqualValues(t, seq0, resultPayload)
-					if !bytes.Equal(testPayload, resultPayload) {
+
-						t.Errorf("Expecting %x, got %x", testPayload, resultPayload)
+					// Second
-					}
+					_, err = io.ReadFull(stream, resultPayload)
+					assert.NoError(t, err)
+					assert.EqualValues(t, seq1, resultPayload)
+
+					// Third
+					_, err = io.ReadFull(stream, resultPayload)
+					assert.NoError(t, err)
+					assert.EqualValues(t, seq2, resultPayload)
 				})
 			}
+
 		})
 	}
 }
@@ -94,10 +212,9 @@ func TestRecvDataFromRemote_Closing_InOrder(t *testing.T) {
 
 	var sessionKey [32]byte
 	rand.Read(sessionKey[:])
-	obfuscator, _ := MakeObfuscator(EncryptionMethodPlain, sessionKey)
 
 	seshConfig := seshConfigs["ordered"]
-	seshConfig.Obfuscator = obfuscator
+	seshConfig.Obfuscator, _ = MakeObfuscator(EncryptionMethodPlain, sessionKey)
 	sesh := MakeSession(0, seshConfig)
 
 	f1 := &Frame{
@@ -107,7 +224,7 @@ func TestRecvDataFromRemote_Closing_InOrder(t *testing.T) {
 		testPayload,
 	}
 	// create stream 1
-	n, _ := sesh.Obfs(f1, obfsBuf, 0)
+	n, _ := sesh.obfuscate(f1, obfsBuf, 0)
 	err := sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving normal frame for stream 1: %v", err)
@@ -129,7 +246,7 @@ func TestRecvDataFromRemote_Closing_InOrder(t *testing.T) {
 		closingNothing,
 		testPayload,
 	}
-	n, _ = sesh.Obfs(f2, obfsBuf, 0)
+	n, _ = sesh.obfuscate(f2, obfsBuf, 0)
 	err = sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving normal frame for stream 2: %v", err)
@@ -151,7 +268,7 @@ func TestRecvDataFromRemote_Closing_InOrder(t *testing.T) {
 		closingStream,
 		testPayload,
 	}
-	n, _ = sesh.Obfs(f1CloseStream, obfsBuf, 0)
+	n, _ = sesh.obfuscate(f1CloseStream, obfsBuf, 0)
 	err = sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving stream closing frame for stream 1: %v", err)
@@ -180,7 +297,7 @@ func TestRecvDataFromRemote_Closing_InOrder(t *testing.T) {
 	}
 
 	// close stream 1 again
-	n, _ = sesh.Obfs(f1CloseStream, obfsBuf, 0)
+	n, _ = sesh.obfuscate(f1CloseStream, obfsBuf, 0)
 	err = sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving stream closing frame for stream 1 %v", err)
@@ -203,7 +320,7 @@ func TestRecvDataFromRemote_Closing_InOrder(t *testing.T) {
 		Closing:  closingSession,
 		Payload:  testPayload,
 	}
-	n, _ = sesh.Obfs(fCloseSession, obfsBuf, 0)
+	n, _ = sesh.obfuscate(fCloseSession, obfsBuf, 0)
 	err = sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving session closing frame: %v", err)
@@ -233,10 +350,9 @@ func TestRecvDataFromRemote_Closing_OutOfOrder(t *testing.T) {
 
 	var sessionKey [32]byte
 	rand.Read(sessionKey[:])
-	obfuscator, _ := MakeObfuscator(EncryptionMethodPlain, sessionKey)
 
 	seshConfig := seshConfigs["ordered"]
-	seshConfig.Obfuscator = obfuscator
+	seshConfig.Obfuscator, _ = MakeObfuscator(EncryptionMethodPlain, sessionKey)
 	sesh := MakeSession(0, seshConfig)
 
 	// receive stream 1 closing first
@@ -246,7 +362,7 @@ func TestRecvDataFromRemote_Closing_OutOfOrder(t *testing.T) {
 		closingStream,
 		testPayload,
 	}
-	n, _ := sesh.Obfs(f1CloseStream, obfsBuf, 0)
+	n, _ := sesh.obfuscate(f1CloseStream, obfsBuf, 0)
 	err := sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving out of order stream closing frame for stream 1: %v", err)
@@ -268,7 +384,7 @@ func TestRecvDataFromRemote_Closing_OutOfOrder(t *testing.T) {
 		closingNothing,
 		testPayload,
 	}
-	n, _ = sesh.Obfs(f1, obfsBuf, 0)
+	n, _ = sesh.obfuscate(f1, obfsBuf, 0)
 	err = sesh.recvDataFromRemote(obfsBuf[:n])
 	if err != nil {
 		t.Fatalf("receiving normal frame for stream 1: %v", err)
@@ -330,7 +446,7 @@ func TestParallelStreams(t *testing.T) {
 				wg.Add(1)
 				go func(frame *Frame) {
 					obfsBuf := make([]byte, obfsBufLen)
-					n, _ := sesh.Obfs(frame, obfsBuf, 0)
+					n, _ := sesh.obfuscate(frame, obfsBuf, 0)
 					obfsBuf = obfsBuf[0:n]
 
 					err := sesh.recvDataFromRemote(obfsBuf)
@@ -415,7 +531,7 @@ func TestSession_timeoutAfter(t *testing.T) {
 	}
 }
 
-func BenchmarkRecvDataFromRemote_Ordered(b *testing.B) {
+func BenchmarkRecvDataFromRemote(b *testing.B) {
 	testPayload := make([]byte, testPayloadLen)
 	rand.Read(testPayload)
 	f := &Frame{
@@ -428,33 +544,34 @@ func BenchmarkRecvDataFromRemote_Ordered(b *testing.B) {
 	var sessionKey [32]byte
 	rand.Read(sessionKey[:])
 
-	table := map[string]byte{
-		"plain":            EncryptionMethodPlain,
-		"aes-gcm":          EncryptionMethodAES256GCM,
-		"chacha20poly1305": EncryptionMethodChaha20Poly1305,
-	}
-
 	const maxIter = 100_000 // run with -benchtime 100000x to avoid index out of bounds panic
-	for name, ep := range table {
+	for name, ep := range encryptionMethods {
 		ep := ep
 		b.Run(name, func(b *testing.B) {
-			seshConfig := seshConfigs["ordered"]
+			for seshType, seshConfig := range seshConfigs {
-			obfuscator, _ := MakeObfuscator(ep, sessionKey)
+				b.Run(seshType, func(b *testing.B) {
-			seshConfig.Obfuscator = obfuscator
+					seshConfig.Obfuscator, _ = MakeObfuscator(ep, sessionKey)
-			sesh := MakeSession(0, seshConfig)
+					sesh := MakeSession(0, seshConfig)
 
-			binaryFrames := [maxIter][]byte{}
+					go func() {
-			for i := 0; i < maxIter; i++ {
+						stream, _ := sesh.Accept()
-				obfsBuf := make([]byte, obfsBufLen)
+						stream.(*Stream).WriteTo(ioutil.Discard)
-				n, _ := sesh.Obfs(f, obfsBuf, 0)
+					}()
-				binaryFrames[i] = obfsBuf[:n]
-				f.Seq++
-			}
 
-			b.SetBytes(int64(len(f.Payload)))
+					binaryFrames := [maxIter][]byte{}
-			b.ResetTimer()
+					for i := 0; i < maxIter; i++ {
-			for i := 0; i < b.N; i++ {
+						obfsBuf := make([]byte, obfsBufLen)
-				sesh.recvDataFromRemote(binaryFrames[i])
+						n, _ := sesh.obfuscate(f, obfsBuf, 0)
+						binaryFrames[i] = obfsBuf[:n]
+						f.Seq++
+					}
+
+					b.SetBytes(int64(len(f.Payload)))
+					b.ResetTimer()
+					for i := 0; i < b.N; i++ {
+						sesh.recvDataFromRemote(binaryFrames[i])
+					}
+				})
 			}
 		})
 	}
@@ -464,21 +581,13 @@ func BenchmarkMultiStreamWrite(b *testing.B) {
 	var sessionKey [32]byte
 	rand.Read(sessionKey[:])
 
-	table := map[string]byte{
-		"plain":            EncryptionMethodPlain,
-		"aes-gcm":          EncryptionMethodAES256GCM,
-		"chacha20poly1305": EncryptionMethodChaha20Poly1305,
-	}
-
 	testPayload := make([]byte, testPayloadLen)
 
-	for name, ep := range table {
+	for name, ep := range encryptionMethods {
 		b.Run(name, func(b *testing.B) {
 			for seshType, seshConfig := range seshConfigs {
-				seshConfig := seshConfig
 				b.Run(seshType, func(b *testing.B) {
-					obfuscator, _ := MakeObfuscator(ep, sessionKey)
+					seshConfig.Obfuscator, _ = MakeObfuscator(ep, sessionKey)
-					seshConfig.Obfuscator = obfuscator
 					sesh := MakeSession(0, seshConfig)
 					sesh.AddConnection(connutil.Discard())
 					b.ResetTimer()
@@ -494,3 +603,36 @@ func BenchmarkMultiStreamWrite(b *testing.B) {
 		})
 	}
 }
+
+func BenchmarkLatency(b *testing.B) {
+	var sessionKey [32]byte
+	rand.Read(sessionKey[:])
+
+	for name, ep := range encryptionMethods {
+		b.Run(name, func(b *testing.B) {
+			for seshType, seshConfig := range seshConfigs {
+				b.Run(seshType, func(b *testing.B) {
+					seshConfig.Obfuscator, _ = MakeObfuscator(ep, sessionKey)
+					clientSesh := MakeSession(0, seshConfig)
+					serverSesh := MakeSession(0, seshConfig)
+
+					c, s := net.Pipe()
+					clientSesh.AddConnection(c)
+					serverSesh.AddConnection(s)
+
+					buf := make([]byte, 64)
+					clientStream, _ := clientSesh.OpenStream()
+					clientStream.Write(buf)
+					serverStream, _ := serverSesh.Accept()
+					io.ReadFull(serverStream, buf)
+
+					b.ResetTimer()
+					for i := 0; i < b.N; i++ {
+						clientStream.Write(buf)
+						io.ReadFull(serverStream, buf)
+					}
+				})
+			}
+		})
+	}
+}

internal/multiplex/stream.go

@@ -113,7 +113,7 @@ func (s *Stream) WriteTo(w io.Writer) (int64, error) {
 }
 
 func (s *Stream) obfuscateAndSend(buf []byte, payloadOffsetInBuf int) error {
-	cipherTextLen, err := s.session.Obfs(&s.writingFrame, buf, payloadOffsetInBuf)
+	cipherTextLen, err := s.session.obfuscate(&s.writingFrame, buf, payloadOffsetInBuf)
 	s.writingFrame.Seq++
 	if err != nil {
 		return err

internal/multiplex/stream_test.go

@@ -142,7 +142,7 @@ func TestStream_Close(t *testing.T) {
 		writingEnd := common.NewTLSConn(rawWritingEnd)
 
 		obfsBuf := make([]byte, 512)
-		i, _ := sesh.Obfs(dataFrame, obfsBuf, 0)
+		i, _ := sesh.obfuscate(dataFrame, obfsBuf, 0)
 		_, err := writingEnd.Write(obfsBuf[:i])
 		if err != nil {
 			t.Error("failed to write from remote end")
@@ -185,7 +185,7 @@ func TestStream_Close(t *testing.T) {
 		writingEnd := common.NewTLSConn(rawWritingEnd)
 
 		obfsBuf := make([]byte, 512)
-		i, err := sesh.Obfs(dataFrame, obfsBuf, 0)
+		i, err := sesh.obfuscate(dataFrame, obfsBuf, 0)
 		if err != nil {
 			t.Errorf("failed to obfuscate frame %v", err)
 		}
@@ -207,7 +207,7 @@ func TestStream_Close(t *testing.T) {
 			testPayload,
 		}
 
-		i, err = sesh.Obfs(closingFrame, obfsBuf, 0)
+		i, err = sesh.obfuscate(closingFrame, obfsBuf, 0)
 		if err != nil {
 			t.Errorf("failed to obfuscate frame %v", err)
 		}
@@ -223,7 +223,7 @@ func TestStream_Close(t *testing.T) {
 			testPayload,
 		}
 
-		i, err = sesh.Obfs(closingFrameDup, obfsBuf, 0)
+		i, err = sesh.obfuscate(closingFrameDup, obfsBuf, 0)
 		if err != nil {
 			t.Errorf("failed to obfuscate frame %v", err)
 		}
@@ -275,7 +275,7 @@ func TestStream_Read(t *testing.T) {
 			obfsBuf := make([]byte, 512)
 			t.Run("Plain read", func(t *testing.T) {
 				f.StreamID = streamID
-				i, _ := sesh.Obfs(f, obfsBuf, 0)
+				i, _ := sesh.obfuscate(f, obfsBuf, 0)
 				streamID++
 				writingEnd.Write(obfsBuf[:i])
 				stream, err := sesh.Accept()
@@ -300,7 +300,7 @@ func TestStream_Read(t *testing.T) {
 			})
 			t.Run("Nil buf", func(t *testing.T) {
 				f.StreamID = streamID
-				i, _ := sesh.Obfs(f, obfsBuf, 0)
+				i, _ := sesh.obfuscate(f, obfsBuf, 0)
 				streamID++
 				writingEnd.Write(obfsBuf[:i])
 				stream, _ := sesh.Accept()
@@ -312,7 +312,7 @@ func TestStream_Read(t *testing.T) {
 			})
 			t.Run("Read after stream close", func(t *testing.T) {
 				f.StreamID = streamID
-				i, _ := sesh.Obfs(f, obfsBuf, 0)
+				i, _ := sesh.obfuscate(f, obfsBuf, 0)
 				streamID++
 				writingEnd.Write(obfsBuf[:i])
 				stream, _ := sesh.Accept()
@@ -337,7 +337,7 @@ func TestStream_Read(t *testing.T) {
 			})
 			t.Run("Read after session close", func(t *testing.T) {
 				f.StreamID = streamID
-				i, _ := sesh.Obfs(f, obfsBuf, 0)
+				i, _ := sesh.obfuscate(f, obfsBuf, 0)
 				streamID++
 				writingEnd.Write(obfsBuf[:i])
 				stream, _ := sesh.Accept()

internal/server/dispatcher.go

@@ -236,7 +236,7 @@ func dispatchConnection(conn net.Conn, sta *State) {
 		return
 	}
 
-	preparedConn, err := finishHandshake(conn, sesh.SessionKey, sta.WorldState.Rand)
+	preparedConn, err := finishHandshake(conn, sesh.GetSessionKey(), sta.WorldState.Rand)
 	if err != nil {
 		log.Error(err)
 		return