From 50aeefcb5198d99777e19f9a0100fe74af630dfb Mon Sep 17 00:00:00 2001
From: Mathias Hall-Andersen <mathias@hall-andersen.dk>
Date: Fri, 23 Jun 2017 13:41:59 +0200
Subject: Beginning work noise handshake

---
 src/noise_protocol.go | 179 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 179 insertions(+)
 create mode 100644 src/noise_protocol.go

(limited to 'src/noise_protocol.go')

diff --git a/src/noise_protocol.go b/src/noise_protocol.go
new file mode 100644
index 0000000..e7c8774
--- /dev/null
+++ b/src/noise_protocol.go
@@ -0,0 +1,179 @@
+package main
+
+import (
+	"errors"
+	"golang.org/x/crypto/blake2s"
+	"golang.org/x/crypto/chacha20poly1305"
+	"golang.org/x/crypto/poly1305"
+	"sync"
+)
+
+const (
+	HandshakeInitialCreated = iota
+	HandshakeInitialConsumed
+	HandshakeResponseCreated
+)
+
+const (
+	NoiseConstruction = "Noise_IKpsk2_25519_ChaChaPoly_BLAKE2s"
+	WGIdentifier      = "WireGuard v1 zx2c4 Jason@zx2c4.com"
+	WGLabelMAC1       = "mac1----"
+	WGLabelCookie     = "cookie--"
+)
+
+const (
+	MessageInitalType         = 1
+	MessageResponseType       = 2
+	MessageCookieResponseType = 3
+	MessageTransportType      = 4
+)
+
+type MessageInital struct {
+	Type      uint32
+	Sender    uint32
+	Ephemeral NoisePublicKey
+	Static    [NoisePublicKeySize + poly1305.TagSize]byte
+	Timestamp [TAI64NSize + poly1305.TagSize]byte
+	Mac1      [blake2s.Size128]byte
+	Mac2      [blake2s.Size128]byte
+}
+
+type MessageResponse struct {
+	Type      uint32
+	Sender    uint32
+	Reciever  uint32
+	Ephemeral NoisePublicKey
+	Empty     [poly1305.TagSize]byte
+	Mac1      [blake2s.Size128]byte
+	Mac2      [blake2s.Size128]byte
+}
+
+type MessageTransport struct {
+	Type     uint32
+	Reciever uint32
+	Counter  uint64
+	Content  []byte
+}
+
+type Handshake struct {
+	lock         sync.Mutex
+	state        int
+	chainKey     [blake2s.Size]byte // chain key
+	hash         [blake2s.Size]byte // hash value
+	staticStatic NoisePublicKey     // precomputed DH(S_i, S_r)
+	ephemeral    NoisePrivateKey    // ephemeral secret key
+	remoteIndex  uint32             // index for sending
+	device       *Device
+	peer         *Peer
+}
+
+var (
+	ZeroNonce      [chacha20poly1305.NonceSize]byte
+	InitalChainKey [blake2s.Size]byte
+	InitalHash     [blake2s.Size]byte
+)
+
+func init() {
+	InitalChainKey = blake2s.Sum256([]byte(NoiseConstruction))
+	InitalHash = blake2s.Sum256(append(InitalChainKey[:], []byte(WGIdentifier)...))
+}
+
+func (h *Handshake) Precompute() {
+	h.staticStatic = h.device.privateKey.sharedSecret(h.peer.publicKey)
+}
+
+func (h *Handshake) ConsumeMessageResponse(msg *MessageResponse) {
+
+}
+
+func (h *Handshake) addHash(data []byte) {
+	h.hash = addToHash(h.hash, data)
+}
+
+func (h *Handshake) addChain(data []byte) {
+	h.chainKey = addToChainKey(h.chainKey, data)
+}
+
+func (h *Handshake) CreateMessageInital() (*MessageInital, error) {
+	h.lock.Lock()
+	defer h.lock.Unlock()
+
+	// reset handshake
+
+	var err error
+	h.ephemeral, err = newPrivateKey()
+	if err != nil {
+		return nil, err
+	}
+	h.chainKey = InitalChainKey
+	h.hash = addToHash(InitalHash, h.device.publicKey[:])
+
+	// create ephemeral key
+
+	var msg MessageInital
+	msg.Type = MessageInitalType
+	msg.Sender = h.device.NewID(h)
+	msg.Ephemeral = h.ephemeral.publicKey()
+	h.chainKey = addToChainKey(h.chainKey, msg.Ephemeral[:])
+	h.hash = addToHash(h.hash, msg.Ephemeral[:])
+
+	// encrypt long-term "identity key"
+
+	func() {
+		var key [chacha20poly1305.KeySize]byte
+		ss := h.ephemeral.sharedSecret(h.peer.publicKey)
+		h.chainKey, key = KDF2(h.chainKey[:], ss[:])
+		aead, _ := chacha20poly1305.New(key[:])
+		aead.Seal(msg.Static[:0], ZeroNonce[:], h.device.publicKey[:], nil)
+	}()
+	h.addHash(msg.Static[:])
+
+	// encrypt timestamp
+
+	timestamp := Timestamp()
+	func() {
+		var key [chacha20poly1305.KeySize]byte
+		h.chainKey, key = KDF2(h.chainKey[:], h.staticStatic[:])
+		aead, _ := chacha20poly1305.New(key[:])
+		aead.Seal(msg.Timestamp[:0], ZeroNonce[:], timestamp[:], nil)
+	}()
+	h.addHash(msg.Timestamp[:])
+	h.state = HandshakeInitialCreated
+	return &msg, nil
+}
+
+func (h *Handshake) ConsumeMessageInitial(msg *MessageInital) error {
+	if msg.Type != MessageInitalType {
+		panic(errors.New("bug: invalid inital message type"))
+	}
+
+	hash := addToHash(InitalHash, h.device.publicKey[:])
+	chainKey := addToChainKey(InitalChainKey, msg.Ephemeral[:])
+	hash = addToHash(hash, msg.Ephemeral[:])
+
+	//
+
+	ephemeral, err := newPrivateKey()
+	if err != nil {
+		return err
+	}
+
+	// update handshake state
+
+	h.lock.Lock()
+	defer h.lock.Unlock()
+
+	h.hash = hash
+	h.chainKey = chainKey
+	h.remoteIndex = msg.Sender
+	h.ephemeral = ephemeral
+	h.state = HandshakeInitialConsumed
+
+	return nil
+
+}
+
+func (h *Handshake) CreateMessageResponse() []byte {
+
+	return nil
+}
-- 
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