Merge pull request #2226 from fjl/eip-8

p2p, p2p/discover: EIP-8 changes

crypto/ecies/ecies.go

@@ -192,11 +192,9 @@ func concatKDF(hash hash.Hash, z, s1 []byte, kdLen int) (k []byte, err error) {
 // messageTag computes the MAC of a message (called the tag) as per
 // SEC 1, 3.5.
 func messageTag(hash func() hash.Hash, km, msg, shared []byte) []byte {
-	if shared == nil {
-		shared = make([]byte, 0)
-	}
 	mac := hmac.New(hash, km)
 	mac.Write(msg)
+	mac.Write(shared)
 	tag := mac.Sum(nil)
 	return tag
 }
@@ -243,9 +241,11 @@ func symDecrypt(rand io.Reader, params *ECIESParams, key, ct []byte) (m []byte,
 	return
 }
 
-// Encrypt encrypts a message using ECIES as specified in SEC 1, 5.1. If
+// Encrypt encrypts a message using ECIES as specified in SEC 1, 5.1.
-// the shared information parameters aren't being used, they should be
+//
-// nil.
+// s1 and s2 contain shared information that is not part of the resulting
+// ciphertext. s1 is fed into key derivation, s2 is fed into the MAC. If the
+// shared information parameters aren't being used, they should be nil.
 func Encrypt(rand io.Reader, pub *PublicKey, m, s1, s2 []byte) (ct []byte, err error) {
 	params := pub.Params
 	if params == nil {

crypto/ecies/ecies_test.go

@@ -408,6 +408,36 @@ func TestEncryptDecrypt(t *testing.T) {
 	}
 }
 
+func TestDecryptShared2(t *testing.T) {
+	prv, err := GenerateKey(rand.Reader, DefaultCurve, nil)
+	if err != nil {
+		t.Fatal(err)
+	}
+	message := []byte("Hello, world.")
+	shared2 := []byte("shared data 2")
+	ct, err := Encrypt(rand.Reader, &prv.PublicKey, message, nil, shared2)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	// Check that decrypting with correct shared data works.
+	pt, err := prv.Decrypt(rand.Reader, ct, nil, shared2)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(pt, message) {
+		t.Fatal("ecies: plaintext doesn't match message")
+	}
+
+	// Decrypting without shared data or incorrect shared data fails.
+	if _, err = prv.Decrypt(rand.Reader, ct, nil, nil); err == nil {
+		t.Fatal("ecies: decrypting without shared data didn't fail")
+	}
+	if _, err = prv.Decrypt(rand.Reader, ct, nil, []byte("garbage")); err == nil {
+		t.Fatal("ecies: decrypting with incorrect shared data didn't fail")
+	}
+}
+
 // TestMarshalEncryption validates the encode/decode produces a valid
 // ECIES encryption key.
 func TestMarshalEncryption(t *testing.T) {

p2p/discover/udp.go

@@ -67,6 +67,8 @@ type (
 		Version    uint
 		From, To   rpcEndpoint
 		Expiration uint64
+		// Ignore additional fields (for forward compatibility).
+		Rest []rlp.RawValue `rlp:"tail"`
 	}
 
 	// pong is the reply to ping.
@@ -78,18 +80,24 @@ type (
 
 		ReplyTok   []byte // This contains the hash of the ping packet.
 		Expiration uint64 // Absolute timestamp at which the packet becomes invalid.
+		// Ignore additional fields (for forward compatibility).
+		Rest []rlp.RawValue `rlp:"tail"`
 	}
 
 	// findnode is a query for nodes close to the given target.
 	findnode struct {
 		Target     NodeID // doesn't need to be an actual public key
 		Expiration uint64
+		// Ignore additional fields (for forward compatibility).
+		Rest []rlp.RawValue `rlp:"tail"`
 	}
 
 	// reply to findnode
 	neighbors struct {
 		Nodes      []rpcNode
 		Expiration uint64
+		// Ignore additional fields (for forward compatibility).
+		Rest []rlp.RawValue `rlp:"tail"`
 	}
 
 	rpcNode struct {
@@ -522,7 +530,8 @@ func decodePacket(buf []byte) (packet, NodeID, []byte, error) {
 	default:
 		return nil, fromID, hash, fmt.Errorf("unknown type: %d", ptype)
 	}
-	err = rlp.DecodeBytes(sigdata[1:], req)
+	s := rlp.NewStream(bytes.NewReader(sigdata[1:]), 0)
+	err = s.Decode(req)
 	return req, fromID, hash, err
 }
 

p2p/discover/udp_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"crypto/ecdsa"
 	"encoding/binary"
+	"encoding/hex"
 	"errors"
 	"fmt"
 	"io"
@@ -33,7 +34,9 @@ import (
 	"time"
 
 	"github.com/davecgh/go-spew/spew"
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/rlp"
 )
 
 func init() {
@@ -434,6 +437,115 @@ func TestUDP_successfulPing(t *testing.T) {
 	}
 }
 
+var testPackets = []struct {
+	input      string
+	wantPacket interface{}
+}{
+	{
+		input: "71dbda3a79554728d4f94411e42ee1f8b0d561c10e1e5f5893367948c6a7d70bb87b235fa28a77070271b6c164a2dce8c7e13a5739b53b5e96f2e5acb0e458a02902f5965d55ecbeb2ebb6cabb8b2b232896a36b737666c55265ad0a68412f250001ea04cb847f000001820cfa8215a8d790000000000000000000000000000000018208ae820d058443b9a355",
+		wantPacket: &ping{
+			Version:    4,
+			From:       rpcEndpoint{net.ParseIP("127.0.0.1").To4(), 3322, 5544},
+			To:         rpcEndpoint{net.ParseIP("::1"), 2222, 3333},
+			Expiration: 1136239445,
+			Rest:       []rlp.RawValue{},
+		},
+	},
+	{
+		input: "e9614ccfd9fc3e74360018522d30e1419a143407ffcce748de3e22116b7e8dc92ff74788c0b6663aaa3d67d641936511c8f8d6ad8698b820a7cf9e1be7155e9a241f556658c55428ec0563514365799a4be2be5a685a80971ddcfa80cb422cdd0101ec04cb847f000001820cfa8215a8d790000000000000000000000000000000018208ae820d058443b9a3550102",
+		wantPacket: &ping{
+			Version:    4,
+			From:       rpcEndpoint{net.ParseIP("127.0.0.1").To4(), 3322, 5544},
+			To:         rpcEndpoint{net.ParseIP("::1"), 2222, 3333},
+			Expiration: 1136239445,
+			Rest:       []rlp.RawValue{{0x01}, {0x02}},
+		},
+	},
+	{
+		input: "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",
+		wantPacket: &ping{
+			Version:    555,
+			From:       rpcEndpoint{net.ParseIP("2001:db8:3c4d:15::abcd:ef12"), 3322, 5544},
+			To:         rpcEndpoint{net.ParseIP("2001:db8:85a3:8d3:1319:8a2e:370:7348"), 2222, 33338},
+			Expiration: 1136239445,
+			Rest:       []rlp.RawValue{{0xC5, 0x01, 0x02, 0x03, 0x04, 0x05}},
+		},
+	},
+	{
+		input: "09b2428d83348d27cdf7064ad9024f526cebc19e4958f0fdad87c15eb598dd61d08423e0bf66b2069869e1724125f820d851c136684082774f870e614d95a2855d000f05d1648b2d5945470bc187c2d2216fbe870f43ed0909009882e176a46b0102f846d79020010db885a308d313198a2e037073488208ae82823aa0fbc914b16819237dcd8801d7e53f69e9719adecb3cc0e790c57e91ca4461c9548443b9a355c6010203c2040506a0c969a58f6f9095004c0177a6b47f451530cab38966a25cca5cb58f055542124e",
+		wantPacket: &pong{
+			To:         rpcEndpoint{net.ParseIP("2001:db8:85a3:8d3:1319:8a2e:370:7348"), 2222, 33338},
+			ReplyTok:   common.Hex2Bytes("fbc914b16819237dcd8801d7e53f69e9719adecb3cc0e790c57e91ca4461c954"),
+			Expiration: 1136239445,
+			Rest:       []rlp.RawValue{{0xC6, 0x01, 0x02, 0x03, 0xC2, 0x04, 0x05}, {0x06}},
+		},
+	},
+	{
+		input: "c7c44041b9f7c7e41934417ebac9a8e1a4c6298f74553f2fcfdcae6ed6fe53163eb3d2b52e39fe91831b8a927bf4fc222c3902202027e5e9eb812195f95d20061ef5cd31d502e47ecb61183f74a504fe04c51e73df81f25c4d506b26db4517490103f84eb840ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd31387574077f301b421bc84df7266c44e9e6d569fc56be00812904767bf5ccd1fc7f8443b9a35582999983999999280dc62cc8255c73471e0a61da0c89acdc0e035e260add7fc0c04ad9ebf3919644c91cb247affc82b69bd2ca235c71eab8e49737c937a2c396",
+		wantPacket: &findnode{
+			Target:     MustHexID("ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd31387574077f301b421bc84df7266c44e9e6d569fc56be00812904767bf5ccd1fc7f"),
+			Expiration: 1136239445,
+			Rest:       []rlp.RawValue{{0x82, 0x99, 0x99}, {0x83, 0x99, 0x99, 0x99}},
+		},
+	},
+	{
+		input: "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",
+		wantPacket: &neighbors{
+			Nodes: []rpcNode{
+				{
+					ID:  MustHexID("3155e1427f85f10a5c9a7755877748041af1bcd8d474ec065eb33df57a97babf54bfd2103575fa829115d224c523596b401065a97f74010610fce76382c0bf32"),
+					IP:  net.ParseIP("99.33.22.55").To4(),
+					UDP: 4444,
+					TCP: 4445,
+				},
+				{
+					ID:  MustHexID("312c55512422cf9b8a4097e9a6ad79402e87a15ae909a4bfefa22398f03d20951933beea1e4dfa6f968212385e829f04c2d314fc2d4e255e0d3bc08792b069db"),
+					IP:  net.ParseIP("1.2.3.4").To4(),
+					UDP: 1,
+					TCP: 1,
+				},
+				{
+					ID:  MustHexID("38643200b172dcfef857492156971f0e6aa2c538d8b74010f8e140811d53b98c765dd2d96126051913f44582e8c199ad7c6d6819e9a56483f637feaac9448aac"),
+					IP:  net.ParseIP("2001:db8:3c4d:15::abcd:ef12"),
+					UDP: 3333,
+					TCP: 3333,
+				},
+				{
+					ID:  MustHexID("8dcab8618c3253b558d459da53bd8fa68935a719aff8b811197101a4b2b47dd2d47295286fc00cc081bb542d760717d1bdd6bec2c37cd72eca367d6dd3b9df73"),
+					IP:  net.ParseIP("2001:db8:85a3:8d3:1319:8a2e:370:7348"),
+					UDP: 999,
+					TCP: 1000,
+				},
+			},
+			Expiration: 1136239445,
+			Rest:       []rlp.RawValue{{0x01}, {0x02}, {0x03}},
+		},
+	},
+}
+
+func TestForwardCompatibility(t *testing.T) {
+	testkey, _ := crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+	wantNodeID := PubkeyID(&testkey.PublicKey)
+
+	for _, test := range testPackets {
+		input, err := hex.DecodeString(test.input)
+		if err != nil {
+			t.Fatalf("invalid hex: %s", test.input)
+		}
+		packet, nodeid, _, err := decodePacket(input)
+		if err != nil {
+			t.Errorf("did not accept packet %s\n%v", test.input, err)
+			continue
+		}
+		if !reflect.DeepEqual(packet, test.wantPacket) {
+			t.Errorf("got %s\nwant %s", spew.Sdump(packet), spew.Sdump(test.wantPacket))
+		}
+		if nodeid != wantNodeID {
+			t.Errorf("got id %v\nwant id %v", nodeid, wantNodeID)
+		}
+	}
+}
+
 // dgramPipe is a fake UDP socket. It queues all sent datagrams.
 type dgramPipe struct {
 	mu      *sync.Mutex

p2p/message_test.go

@@ -143,7 +143,8 @@ func TestEOFSignal(t *testing.T) {
 }
 
 func unhex(str string) []byte {
-	b, err := hex.DecodeString(strings.Replace(str, "\n", "", -1))
+	r := strings.NewReplacer("\t", "", " ", "", "\n", "")
+	b, err := hex.DecodeString(r.Replace(str))
 	if err != nil {
 		panic(fmt.Sprintf("invalid hex string: %q", str))
 	}

p2p/peer.go

@@ -56,6 +56,9 @@ type protoHandshake struct {
 	Caps       []Cap
 	ListenPort uint64
 	ID         discover.NodeID
+
+	// Ignore additional fields (for forward compatibility).
+	Rest []rlp.RawValue `rlp:"tail"`
 }
 
 // Peer represents a connected remote node.

p2p/rlpx.go

@@ -24,11 +24,14 @@ import (
 	"crypto/elliptic"
 	"crypto/hmac"
 	"crypto/rand"
+	"encoding/binary"
 	"errors"
 	"fmt"
 	"hash"
 	"io"
+	mrand "math/rand"
 	"net"
+	"os"
 	"sync"
 	"time"
 
@@ -51,9 +54,10 @@ const (
 	authMsgLen  = sigLen + shaLen + pubLen + shaLen + 1
 	authRespLen = pubLen + shaLen + 1
 
-	eciesBytes     = 65 + 16 + 32
+	eciesOverhead = 65 /* pubkey */ + 16 /* IV */ + 32 /* MAC */
-	encAuthMsgLen  = authMsgLen + eciesBytes  // size of the final ECIES payload sent as initiator's handshake
+
-	encAuthRespLen = authRespLen + eciesBytes // size of the final ECIES payload sent as receiver's handshake
+	encAuthMsgLen  = authMsgLen + eciesOverhead  // size of encrypted pre-EIP-8 initiator handshake
+	encAuthRespLen = authRespLen + eciesOverhead // size of encrypted pre-EIP-8 handshake reply
 
 	// total timeout for encryption handshake and protocol
 	// handshake in both directions.
@@ -151,10 +155,6 @@ func readProtocolHandshake(rw MsgReader, our *protoHandshake) (*protoHandshake,
 	if err := msg.Decode(&hs); err != nil {
 		return nil, err
 	}
-	// validate handshake info
-	if hs.Version != our.Version {
-		return nil, DiscIncompatibleVersion
-	}
 	if (hs.ID == discover.NodeID{}) {
 		return nil, DiscInvalidIdentity
 	}
@@ -200,6 +200,29 @@ type secrets struct {
 	Token                 []byte
 }
 
+// RLPx v4 handshake auth (defined in EIP-8).
+type authMsgV4 struct {
+	gotPlain bool // whether read packet had plain format.
+
+	Signature       [sigLen]byte
+	InitiatorPubkey [pubLen]byte
+	Nonce           [shaLen]byte
+	Version         uint
+
+	// Ignore additional fields (forward-compatibility)
+	Rest []rlp.RawValue `rlp:"tail"`
+}
+
+// RLPx v4 handshake response (defined in EIP-8).
+type authRespV4 struct {
+	RandomPubkey [pubLen]byte
+	Nonce        [shaLen]byte
+	Version      uint
+
+	// Ignore additional fields (forward-compatibility)
+	Rest []rlp.RawValue `rlp:"tail"`
+}
+
 // secrets is called after the handshake is completed.
 // It extracts the connection secrets from the handshake values.
 func (h *encHandshake) secrets(auth, authResp []byte) (secrets, error) {
@@ -215,7 +238,6 @@ func (h *encHandshake) secrets(auth, authResp []byte) (secrets, error) {
 		RemoteID: h.remoteID,
 		AES:      aesSecret,
 		MAC:      crypto.Sha3(ecdheSecret, aesSecret),
-		Token:    crypto.Sha3(sharedSecret),
 	}
 
 	// setup sha3 instances for the MACs
@@ -234,114 +256,89 @@ func (h *encHandshake) secrets(auth, authResp []byte) (secrets, error) {
 	return s, nil
 }
 
-func (h *encHandshake) ecdhShared(prv *ecdsa.PrivateKey) ([]byte, error) {
+// staticSharedSecret returns the static shared secret, the result
+// of key agreement between the local and remote static node key.
+func (h *encHandshake) staticSharedSecret(prv *ecdsa.PrivateKey) ([]byte, error) {
 	return ecies.ImportECDSA(prv).GenerateShared(h.remotePub, sskLen, sskLen)
 }
 
+var configSendEIP = os.Getenv("RLPX_EIP8") != ""
+
 // initiatorEncHandshake negotiates a session token on conn.
 // it should be called on the dialing side of the connection.
 //
 // prv is the local client's private key.
-// token is the token from a previous session with this node.
 func initiatorEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, remoteID discover.NodeID, token []byte) (s secrets, err error) {
-	h, err := newInitiatorHandshake(remoteID)
+	h := &encHandshake{initiator: true, remoteID: remoteID}
+	authMsg, err := h.makeAuthMsg(prv, token)
 	if err != nil {
 		return s, err
 	}
-	auth, err := h.authMsg(prv, token)
+	var authPacket []byte
+	if configSendEIP {
+		authPacket, err = sealEIP8(authMsg, h)
+	} else {
+		authPacket, err = authMsg.sealPlain(h)
+	}
 	if err != nil {
 		return s, err
 	}
-	if _, err = conn.Write(auth); err != nil {
+	if _, err = conn.Write(authPacket); err != nil {
 		return s, err
 	}
 
-	response := make([]byte, encAuthRespLen)
+	authRespMsg := new(authRespV4)
-	if _, err = io.ReadFull(conn, response); err != nil {
+	authRespPacket, err := readHandshakeMsg(authRespMsg, encAuthRespLen, prv, conn)
+	if err != nil {
 		return s, err
 	}
-	if err := h.decodeAuthResp(response, prv); err != nil {
+	if err := h.handleAuthResp(authRespMsg); err != nil {
 		return s, err
 	}
-	return h.secrets(auth, response)
+	return h.secrets(authPacket, authRespPacket)
 }
 
-func newInitiatorHandshake(remoteID discover.NodeID) (*encHandshake, error) {
+// makeAuthMsg creates the initiator handshake message.
-	rpub, err := remoteID.Pubkey()
+func (h *encHandshake) makeAuthMsg(prv *ecdsa.PrivateKey, token []byte) (*authMsgV4, error) {
+	rpub, err := h.remoteID.Pubkey()
 	if err != nil {
 		return nil, fmt.Errorf("bad remoteID: %v", err)
 	}
-	// generate random initiator nonce
+	h.remotePub = ecies.ImportECDSAPublic(rpub)
-	n := make([]byte, shaLen)
+	// Generate random initiator nonce.
-	if _, err := rand.Read(n); err != nil {
+	h.initNonce = make([]byte, shaLen)
+	if _, err := rand.Read(h.initNonce); err != nil {
 		return nil, err
 	}
-	// generate random keypair to use for signing
+	// Generate random keypair to for ECDH.
-	randpriv, err := ecies.GenerateKey(rand.Reader, secp256k1.S256(), nil)
+	h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, secp256k1.S256(), nil)
 	if err != nil {
 		return nil, err
 	}
-	h := &encHandshake{
-		initiator:     true,
-		remoteID:      remoteID,
-		remotePub:     ecies.ImportECDSAPublic(rpub),
-		initNonce:     n,
-		randomPrivKey: randpriv,
-	}
-	return h, nil
-}
 
-// authMsg creates an encrypted initiator handshake message.
+	// Sign known message: static-shared-secret ^ nonce
-func (h *encHandshake) authMsg(prv *ecdsa.PrivateKey, token []byte) ([]byte, error) {
+	token, err = h.staticSharedSecret(prv)
-	var tokenFlag byte
+	if err != nil {
-	if token == nil {
-		// no session token found means we need to generate shared secret.
-		// ecies shared secret is used as initial session token for new peers
-		// generate shared key from prv and remote pubkey
-		var err error
-		if token, err = h.ecdhShared(prv); err != nil {
 		return nil, err
 	}
-	} else {
-		// for known peers, we use stored token from the previous session
-		tokenFlag = 0x01
-	}
-
-	// sign known message:
-	//   ecdh-shared-secret^nonce for new peers
-	//   token^nonce for old peers
 	signed := xor(token, h.initNonce)
 	signature, err := crypto.Sign(signed, h.randomPrivKey.ExportECDSA())
 	if err != nil {
 		return nil, err
 	}
 
-	// encode auth message
+	msg := new(authMsgV4)
-	// signature || sha3(ecdhe-random-pubk) || pubk || nonce || token-flag
+	copy(msg.Signature[:], signature)
-	msg := make([]byte, authMsgLen)
+	copy(msg.InitiatorPubkey[:], crypto.FromECDSAPub(&prv.PublicKey)[1:])
-	n := copy(msg, signature)
+	copy(msg.Nonce[:], h.initNonce)
-	n += copy(msg[n:], crypto.Sha3(exportPubkey(&h.randomPrivKey.PublicKey)))
+	msg.Version = 4
-	n += copy(msg[n:], crypto.FromECDSAPub(&prv.PublicKey)[1:])
+	return msg, nil
-	n += copy(msg[n:], h.initNonce)
-	msg[n] = tokenFlag
-
-	// encrypt auth message using remote-pubk
-	return ecies.Encrypt(rand.Reader, h.remotePub, msg, nil, nil)
 }
 
-// decodeAuthResp decode an encrypted authentication response message.
+func (h *encHandshake) handleAuthResp(msg *authRespV4) (err error) {
-func (h *encHandshake) decodeAuthResp(auth []byte, prv *ecdsa.PrivateKey) error {
+	h.respNonce = msg.Nonce[:]
-	msg, err := crypto.Decrypt(prv, auth)
+	h.remoteRandomPub, err = importPublicKey(msg.RandomPubkey[:])
-	if err != nil {
-		return fmt.Errorf("could not decrypt auth response (%v)", err)
-	}
-	h.respNonce = msg[pubLen : pubLen+shaLen]
-	h.remoteRandomPub, err = importPublicKey(msg[:pubLen])
-	if err != nil {
 	return err
-	}
-	// ignore token flag for now
-	return nil
 }
 
 // receiverEncHandshake negotiates a session token on conn.
@@ -350,99 +347,165 @@ func (h *encHandshake) decodeAuthResp(auth []byte, prv *ecdsa.PrivateKey) error
 // prv is the local client's private key.
 // token is the token from a previous session with this node.
 func receiverEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, token []byte) (s secrets, err error) {
-	// read remote auth sent by initiator.
+	authMsg := new(authMsgV4)
-	auth := make([]byte, encAuthMsgLen)
+	authPacket, err := readHandshakeMsg(authMsg, encAuthMsgLen, prv, conn)
-	if _, err := io.ReadFull(conn, auth); err != nil {
-		return s, err
-	}
-	h, err := decodeAuthMsg(prv, token, auth)
 	if err != nil {
 		return s, err
 	}
+	h := new(encHandshake)
+	if err := h.handleAuthMsg(authMsg, prv); err != nil {
+		return s, err
+	}
 
-	// send auth response
+	authRespMsg, err := h.makeAuthResp()
-	resp, err := h.authResp(prv, token)
 	if err != nil {
 		return s, err
 	}
-	if _, err = conn.Write(resp); err != nil {
+	var authRespPacket []byte
+	if authMsg.gotPlain {
+		authRespPacket, err = authRespMsg.sealPlain(h)
+	} else {
+		authRespPacket, err = sealEIP8(authRespMsg, h)
+	}
+	if err != nil {
 		return s, err
 	}
-
+	if _, err = conn.Write(authRespPacket); err != nil {
-	return h.secrets(auth, resp)
+		return s, err
+	}
+	return h.secrets(authPacket, authRespPacket)
 }
 
-func decodeAuthMsg(prv *ecdsa.PrivateKey, token []byte, auth []byte) (*encHandshake, error) {
+func (h *encHandshake) handleAuthMsg(msg *authMsgV4, prv *ecdsa.PrivateKey) error {
-	var err error
+	// Import the remote identity.
-	h := new(encHandshake)
+	h.initNonce = msg.Nonce[:]
-	// generate random keypair for session
+	h.remoteID = msg.InitiatorPubkey
+	rpub, err := h.remoteID.Pubkey()
+	if err != nil {
+		return fmt.Errorf("bad remoteID: %#v", err)
+	}
+	h.remotePub = ecies.ImportECDSAPublic(rpub)
+
+	// Generate random keypair for ECDH.
+	// If a private key is already set, use it instead of generating one (for testing).
+	if h.randomPrivKey == nil {
 		h.randomPrivKey, err = ecies.GenerateKey(rand.Reader, secp256k1.S256(), nil)
 		if err != nil {
-		return nil, err
+			return err
 		}
-	// generate random nonce
+	}
+
+	// Check the signature.
+	token, err := h.staticSharedSecret(prv)
+	if err != nil {
+		return err
+	}
+	signedMsg := xor(token, h.initNonce)
+	remoteRandomPub, err := secp256k1.RecoverPubkey(signedMsg, msg.Signature[:])
+	if err != nil {
+		return err
+	}
+	h.remoteRandomPub, _ = importPublicKey(remoteRandomPub)
+	return nil
+}
+
+func (h *encHandshake) makeAuthResp() (msg *authRespV4, err error) {
+	// Generate random nonce.
 	h.respNonce = make([]byte, shaLen)
 	if _, err = rand.Read(h.respNonce); err != nil {
 		return nil, err
 	}
 
-	msg, err := crypto.Decrypt(prv, auth)
+	msg = new(authRespV4)
-	if err != nil {
+	copy(msg.Nonce[:], h.respNonce)
-		return nil, fmt.Errorf("could not decrypt auth message (%v)", err)
+	copy(msg.RandomPubkey[:], exportPubkey(&h.randomPrivKey.PublicKey))
-	}
+	msg.Version = 4
-
+	return msg, nil
-	// decode message parameters
-	// signature || sha3(ecdhe-random-pubk) || pubk || nonce || token-flag
-	h.initNonce = msg[authMsgLen-shaLen-1 : authMsgLen-1]
-	copy(h.remoteID[:], msg[sigLen+shaLen:sigLen+shaLen+pubLen])
-	rpub, err := h.remoteID.Pubkey()
-	if err != nil {
-		return nil, fmt.Errorf("bad remoteID: %#v", err)
-	}
-	h.remotePub = ecies.ImportECDSAPublic(rpub)
-
-	// recover remote random pubkey from signed message.
-	if token == nil {
-		// TODO: it is an error if the initiator has a token and we don't. check that.
-
-		// no session token means we need to generate shared secret.
-		// ecies shared secret is used as initial session token for new peers.
-		// generate shared key from prv and remote pubkey.
-		if token, err = h.ecdhShared(prv); err != nil {
-			return nil, err
-		}
-	}
-	signedMsg := xor(token, h.initNonce)
-	remoteRandomPub, err := secp256k1.RecoverPubkey(signedMsg, msg[:sigLen])
-	if err != nil {
-		return nil, err
-	}
-
-	// validate the sha3 of recovered pubkey
-	remoteRandomPubMAC := msg[sigLen : sigLen+shaLen]
-	shaRemoteRandomPub := crypto.Sha3(remoteRandomPub[1:])
-	if !bytes.Equal(remoteRandomPubMAC, shaRemoteRandomPub) {
-		return nil, fmt.Errorf("sha3 of recovered ephemeral pubkey does not match checksum in auth message")
-	}
-
-	h.remoteRandomPub, _ = importPublicKey(remoteRandomPub)
-	return h, nil
 }
 
-// authResp generates the encrypted authentication response message.
+func (msg *authMsgV4) sealPlain(h *encHandshake) ([]byte, error) {
-func (h *encHandshake) authResp(prv *ecdsa.PrivateKey, token []byte) ([]byte, error) {
+	buf := make([]byte, authMsgLen)
-	// responder auth message
+	n := copy(buf, msg.Signature[:])
-	// E(remote-pubk, ecdhe-random-pubk || nonce || 0x0)
+	n += copy(buf[n:], crypto.Sha3(exportPubkey(&h.randomPrivKey.PublicKey)))
-	resp := make([]byte, authRespLen)
+	n += copy(buf[n:], msg.InitiatorPubkey[:])
-	n := copy(resp, exportPubkey(&h.randomPrivKey.PublicKey))
+	n += copy(buf[n:], msg.Nonce[:])
-	n += copy(resp[n:], h.respNonce)
+	buf[n] = 0 // token-flag
-	if token == nil {
+	return ecies.Encrypt(rand.Reader, h.remotePub, buf, nil, nil)
-		resp[n] = 0
+}
-	} else {
+
-		resp[n] = 1
+func (msg *authMsgV4) decodePlain(input []byte) {
+	n := copy(msg.Signature[:], input)
+	n += shaLen // skip sha3(initiator-ephemeral-pubk)
+	n += copy(msg.InitiatorPubkey[:], input[n:])
+	n += copy(msg.Nonce[:], input[n:])
+	msg.Version = 4
+	msg.gotPlain = true
+}
+
+func (msg *authRespV4) sealPlain(hs *encHandshake) ([]byte, error) {
+	buf := make([]byte, authRespLen)
+	n := copy(buf, msg.RandomPubkey[:])
+	n += copy(buf[n:], msg.Nonce[:])
+	return ecies.Encrypt(rand.Reader, hs.remotePub, buf, nil, nil)
+}
+
+func (msg *authRespV4) decodePlain(input []byte) {
+	n := copy(msg.RandomPubkey[:], input)
+	n += copy(msg.Nonce[:], input[n:])
+	msg.Version = 4
+}
+
+var padSpace = make([]byte, 300)
+
+func sealEIP8(msg interface{}, h *encHandshake) ([]byte, error) {
+	buf := new(bytes.Buffer)
+	if err := rlp.Encode(buf, msg); err != nil {
+		return nil, err
 	}
-	// encrypt using remote-pubk
+	// pad with random amount of data. the amount needs to be at least 100 bytes to make
-	return ecies.Encrypt(rand.Reader, h.remotePub, resp, nil, nil)
+	// the message distinguishable from pre-EIP-8 handshakes.
+	pad := padSpace[:mrand.Intn(len(padSpace)-100)+100]
+	buf.Write(pad)
+	prefix := make([]byte, 2)
+	binary.BigEndian.PutUint16(prefix, uint16(buf.Len()+eciesOverhead))
+
+	enc, err := ecies.Encrypt(rand.Reader, h.remotePub, buf.Bytes(), nil, prefix)
+	return append(prefix, enc...), err
+}
+
+type plainDecoder interface {
+	decodePlain([]byte)
+}
+
+func readHandshakeMsg(msg plainDecoder, plainSize int, prv *ecdsa.PrivateKey, r io.Reader) ([]byte, error) {
+	buf := make([]byte, plainSize)
+	if _, err := io.ReadFull(r, buf); err != nil {
+		return buf, err
+	}
+	// Attempt decoding pre-EIP-8 "plain" format.
+	key := ecies.ImportECDSA(prv)
+	if dec, err := key.Decrypt(rand.Reader, buf, nil, nil); err == nil {
+		msg.decodePlain(dec)
+		return buf, nil
+	}
+	// Could be EIP-8 format, try that.
+	prefix := buf[:2]
+	size := binary.BigEndian.Uint16(prefix)
+	if size < uint16(plainSize) {
+		return buf, fmt.Errorf("size underflow, need at least %d bytes", plainSize)
+	}
+	buf = append(buf, make([]byte, size-uint16(plainSize)+2)...)
+	if _, err := io.ReadFull(r, buf[plainSize:]); err != nil {
+		return buf, err
+	}
+	dec, err := key.Decrypt(rand.Reader, buf[2:], nil, prefix)
+	if err != nil {
+		return buf, err
+	}
+	// Can't use rlp.DecodeBytes here because it rejects
+	// trailing data (forward-compatibility).
+	s := rlp.NewStream(bytes.NewReader(dec), 0)
+	return buf, s.Decode(msg)
 }
 
 // importPublicKey unmarshals 512 bit public keys.
@@ -458,7 +521,11 @@ func importPublicKey(pubKey []byte) (*ecies.PublicKey, error) {
 		return nil, fmt.Errorf("invalid public key length %v (expect 64/65)", len(pubKey))
 	}
 	// TODO: fewer pointless conversions
-	return ecies.ImportECDSAPublic(crypto.ToECDSAPub(pubKey65)), nil
+	pub := crypto.ToECDSAPub(pubKey65)
+	if pub.X == nil {
+		return nil, fmt.Errorf("invalid public key")
+	}
+	return ecies.ImportECDSAPublic(pub), nil
 }
 
 func exportPubkey(pub *ecies.PublicKey) []byte {

p2p/rlpx_test.go

@@ -21,6 +21,7 @@ import (
 	"crypto/rand"
 	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"net"
 	"reflect"
@@ -162,6 +163,7 @@ func TestProtocolHandshake(t *testing.T) {
 	wg.Add(2)
 	go func() {
 		defer wg.Done()
+		defer fd1.Close()
 		rlpx := newRLPX(fd0)
 		remid, err := rlpx.doEncHandshake(prv0, node1)
 		if err != nil {
@@ -178,6 +180,7 @@ func TestProtocolHandshake(t *testing.T) {
 			t.Errorf("dial side proto handshake error: %v", err)
 			return
 		}
+		phs.Rest = nil
 		if !reflect.DeepEqual(phs, hs1) {
 			t.Errorf("dial side proto handshake mismatch:\ngot: %s\nwant: %s\n", spew.Sdump(phs), spew.Sdump(hs1))
 			return
@@ -186,6 +189,7 @@ func TestProtocolHandshake(t *testing.T) {
 	}()
 	go func() {
 		defer wg.Done()
+		defer fd1.Close()
 		rlpx := newRLPX(fd1)
 		remid, err := rlpx.doEncHandshake(prv1, nil)
 		if err != nil {
@@ -202,6 +206,7 @@ func TestProtocolHandshake(t *testing.T) {
 			t.Errorf("listen side proto handshake error: %v", err)
 			return
 		}
+		phs.Rest = nil
 		if !reflect.DeepEqual(phs, hs0) {
 			t.Errorf("listen side proto handshake mismatch:\ngot: %s\nwant: %s\n", spew.Sdump(phs), spew.Sdump(hs0))
 			return
@@ -216,7 +221,6 @@ func TestProtocolHandshake(t *testing.T) {
 
 func TestProtocolHandshakeErrors(t *testing.T) {
 	our := &protoHandshake{Version: 3, Caps: []Cap{{"foo", 2}, {"bar", 3}}, Name: "quux"}
-	id := randomID()
 	tests := []struct {
 		code uint64
 		msg  interface{}
@@ -242,11 +246,6 @@ func TestProtocolHandshakeErrors(t *testing.T) {
 			msg:  []byte{1, 2, 3},
 			err:  newPeerError(errInvalidMsg, "(code 0) (size 4) rlp: expected input list for p2p.protoHandshake"),
 		},
-		{
-			code: handshakeMsg,
-			msg:  &protoHandshake{Version: 9944, ID: id},
-			err:  DiscIncompatibleVersion,
-		},
 		{
 			code: handshakeMsg,
 			msg:  &protoHandshake{Version: 3},
@@ -374,3 +373,227 @@ func TestRLPXFrameRW(t *testing.T) {
 		}
 	}
 }
+
+type handshakeAuthTest struct {
+	input       string
+	isPlain     bool
+	wantVersion uint
+	wantRest    []rlp.RawValue
+}
+
+var eip8HandshakeAuthTests = []handshakeAuthTest{
+	// (Auth₁) RLPx v4 plain encoding
+	{
+		input: `
+			048ca79ad18e4b0659fab4853fe5bc58eb83992980f4c9cc147d2aa31532efd29a3d3dc6a3d89eaf
+			913150cfc777ce0ce4af2758bf4810235f6e6ceccfee1acc6b22c005e9e3a49d6448610a58e98744
+			ba3ac0399e82692d67c1f58849050b3024e21a52c9d3b01d871ff5f210817912773e610443a9ef14
+			2e91cdba0bd77b5fdf0769b05671fc35f83d83e4d3b0b000c6b2a1b1bba89e0fc51bf4e460df3105
+			c444f14be226458940d6061c296350937ffd5e3acaceeaaefd3c6f74be8e23e0f45163cc7ebd7622
+			0f0128410fd05250273156d548a414444ae2f7dea4dfca2d43c057adb701a715bf59f6fb66b2d1d2
+			0f2c703f851cbf5ac47396d9ca65b6260bd141ac4d53e2de585a73d1750780db4c9ee4cd4d225173
+			a4592ee77e2bd94d0be3691f3b406f9bba9b591fc63facc016bfa8
+		`,
+		isPlain:     true,
+		wantVersion: 4,
+	},
+	// (Auth₂) EIP-8 encoding
+	{
+		input: `
+			01b304ab7578555167be8154d5cc456f567d5ba302662433674222360f08d5f1534499d3678b513b
+			0fca474f3a514b18e75683032eb63fccb16c156dc6eb2c0b1593f0d84ac74f6e475f1b8d56116b84
+			9634a8c458705bf83a626ea0384d4d7341aae591fae42ce6bd5c850bfe0b999a694a49bbbaf3ef6c
+			da61110601d3b4c02ab6c30437257a6e0117792631a4b47c1d52fc0f8f89caadeb7d02770bf999cc
+			147d2df3b62e1ffb2c9d8c125a3984865356266bca11ce7d3a688663a51d82defaa8aad69da39ab6
+			d5470e81ec5f2a7a47fb865ff7cca21516f9299a07b1bc63ba56c7a1a892112841ca44b6e0034dee
+			70c9adabc15d76a54f443593fafdc3b27af8059703f88928e199cb122362a4b35f62386da7caad09
+			c001edaeb5f8a06d2b26fb6cb93c52a9fca51853b68193916982358fe1e5369e249875bb8d0d0ec3
+			6f917bc5e1eafd5896d46bd61ff23f1a863a8a8dcd54c7b109b771c8e61ec9c8908c733c0263440e
+			2aa067241aaa433f0bb053c7b31a838504b148f570c0ad62837129e547678c5190341e4f1693956c
+			3bf7678318e2d5b5340c9e488eefea198576344afbdf66db5f51204a6961a63ce072c8926c
+		`,
+		wantVersion: 4,
+		wantRest:    []rlp.RawValue{},
+	},
+	// (Auth₃) RLPx v4 EIP-8 encoding with version 56, additional list elements
+	{
+		input: `
+			01b8044c6c312173685d1edd268aa95e1d495474c6959bcdd10067ba4c9013df9e40ff45f5bfd6f7
+			2471f93a91b493f8e00abc4b80f682973de715d77ba3a005a242eb859f9a211d93a347fa64b597bf
+			280a6b88e26299cf263b01b8dfdb712278464fd1c25840b995e84d367d743f66c0e54a586725b7bb
+			f12acca27170ae3283c1073adda4b6d79f27656993aefccf16e0d0409fe07db2dc398a1b7e8ee93b
+			cd181485fd332f381d6a050fba4c7641a5112ac1b0b61168d20f01b479e19adf7fdbfa0905f63352
+			bfc7e23cf3357657455119d879c78d3cf8c8c06375f3f7d4861aa02a122467e069acaf513025ff19
+			6641f6d2810ce493f51bee9c966b15c5043505350392b57645385a18c78f14669cc4d960446c1757
+			1b7c5d725021babbcd786957f3d17089c084907bda22c2b2675b4378b114c601d858802a55345a15
+			116bc61da4193996187ed70d16730e9ae6b3bb8787ebcaea1871d850997ddc08b4f4ea668fbf3740
+			7ac044b55be0908ecb94d4ed172ece66fd31bfdadf2b97a8bc690163ee11f5b575a4b44e36e2bfb2
+			f0fce91676fd64c7773bac6a003f481fddd0bae0a1f31aa27504e2a533af4cef3b623f4791b2cca6
+			d490
+		`,
+		wantVersion: 56,
+		wantRest:    []rlp.RawValue{{0x01}, {0x02}, {0xC2, 0x04, 0x05}},
+	},
+}
+
+type handshakeAckTest struct {
+	input       string
+	wantVersion uint
+	wantRest    []rlp.RawValue
+}
+
+var eip8HandshakeRespTests = []handshakeAckTest{
+	// (Ack₁) RLPx v4 plain encoding
+	{
+		input: `
+			049f8abcfa9c0dc65b982e98af921bc0ba6e4243169348a236abe9df5f93aa69d99cadddaa387662
+			b0ff2c08e9006d5a11a278b1b3331e5aaabf0a32f01281b6f4ede0e09a2d5f585b26513cb794d963
+			5a57563921c04a9090b4f14ee42be1a5461049af4ea7a7f49bf4c97a352d39c8d02ee4acc416388c
+			1c66cec761d2bc1c72da6ba143477f049c9d2dde846c252c111b904f630ac98e51609b3b1f58168d
+			dca6505b7196532e5f85b259a20c45e1979491683fee108e9660edbf38f3add489ae73e3dda2c71b
+			d1497113d5c755e942d1
+		`,
+		wantVersion: 4,
+	},
+	// (Ack₂) EIP-8 encoding
+	{
+		input: `
+			01ea0451958701280a56482929d3b0757da8f7fbe5286784beead59d95089c217c9b917788989470
+			b0e330cc6e4fb383c0340ed85fab836ec9fb8a49672712aeabbdfd1e837c1ff4cace34311cd7f4de
+			05d59279e3524ab26ef753a0095637ac88f2b499b9914b5f64e143eae548a1066e14cd2f4bd7f814
+			c4652f11b254f8a2d0191e2f5546fae6055694aed14d906df79ad3b407d94692694e259191cde171
+			ad542fc588fa2b7333313d82a9f887332f1dfc36cea03f831cb9a23fea05b33deb999e85489e645f
+			6aab1872475d488d7bd6c7c120caf28dbfc5d6833888155ed69d34dbdc39c1f299be1057810f34fb
+			e754d021bfca14dc989753d61c413d261934e1a9c67ee060a25eefb54e81a4d14baff922180c395d
+			3f998d70f46f6b58306f969627ae364497e73fc27f6d17ae45a413d322cb8814276be6ddd13b885b
+			201b943213656cde498fa0e9ddc8e0b8f8a53824fbd82254f3e2c17e8eaea009c38b4aa0a3f306e8
+			797db43c25d68e86f262e564086f59a2fc60511c42abfb3057c247a8a8fe4fb3ccbadde17514b7ac
+			8000cdb6a912778426260c47f38919a91f25f4b5ffb455d6aaaf150f7e5529c100ce62d6d92826a7
+			1778d809bdf60232ae21ce8a437eca8223f45ac37f6487452ce626f549b3b5fdee26afd2072e4bc7
+			5833c2464c805246155289f4
+		`,
+		wantVersion: 4,
+		wantRest:    []rlp.RawValue{},
+	},
+	// (Ack₃) EIP-8 encoding with version 57, additional list elements
+	{
+		input: `
+			01f004076e58aae772bb101ab1a8e64e01ee96e64857ce82b1113817c6cdd52c09d26f7b90981cd7
+			ae835aeac72e1573b8a0225dd56d157a010846d888dac7464baf53f2ad4e3d584531fa203658fab0
+			3a06c9fd5e35737e417bc28c1cbf5e5dfc666de7090f69c3b29754725f84f75382891c561040ea1d
+			dc0d8f381ed1b9d0d4ad2a0ec021421d847820d6fa0ba66eaf58175f1b235e851c7e2124069fbc20
+			2888ddb3ac4d56bcbd1b9b7eab59e78f2e2d400905050f4a92dec1c4bdf797b3fc9b2f8e84a482f3
+			d800386186712dae00d5c386ec9387a5e9c9a1aca5a573ca91082c7d68421f388e79127a5177d4f8
+			590237364fd348c9611fa39f78dcdceee3f390f07991b7b47e1daa3ebcb6ccc9607811cb17ce51f1
+			c8c2c5098dbdd28fca547b3f58c01a424ac05f869f49c6a34672ea2cbbc558428aa1fe48bbfd6115
+			8b1b735a65d99f21e70dbc020bfdface9f724a0d1fb5895db971cc81aa7608baa0920abb0a565c9c
+			436e2fd13323428296c86385f2384e408a31e104670df0791d93e743a3a5194ee6b076fb6323ca59
+			3011b7348c16cf58f66b9633906ba54a2ee803187344b394f75dd2e663a57b956cb830dd7a908d4f
+			39a2336a61ef9fda549180d4ccde21514d117b6c6fd07a9102b5efe710a32af4eeacae2cb3b1dec0
+			35b9593b48b9d3ca4c13d245d5f04169b0b1
+		`,
+		wantVersion: 57,
+		wantRest:    []rlp.RawValue{{0x06}, {0xC2, 0x07, 0x08}, {0x81, 0xFA}},
+	},
+}
+
+func TestHandshakeForwardCompatibility(t *testing.T) {
+	var (
+		keyA, _       = crypto.HexToECDSA("49a7b37aa6f6645917e7b807e9d1c00d4fa71f18343b0d4122a4d2df64dd6fee")
+		keyB, _       = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+		pubA          = crypto.FromECDSAPub(&keyA.PublicKey)[1:]
+		pubB          = crypto.FromECDSAPub(&keyB.PublicKey)[1:]
+		ephA, _       = crypto.HexToECDSA("869d6ecf5211f1cc60418a13b9d870b22959d0c16f02bec714c960dd2298a32d")
+		ephB, _       = crypto.HexToECDSA("e238eb8e04fee6511ab04c6dd3c89ce097b11f25d584863ac2b6d5b35b1847e4")
+		ephPubA       = crypto.FromECDSAPub(&ephA.PublicKey)[1:]
+		ephPubB       = crypto.FromECDSAPub(&ephB.PublicKey)[1:]
+		nonceA        = unhex("7e968bba13b6c50e2c4cd7f241cc0d64d1ac25c7f5952df231ac6a2bda8ee5d6")
+		nonceB        = unhex("559aead08264d5795d3909718cdd05abd49572e84fe55590eef31a88a08fdffd")
+		_, _, _, _    = pubA, pubB, ephPubA, ephPubB
+		authSignature = unhex("299ca6acfd35e3d72d8ba3d1e2b60b5561d5af5218eb5bc182045769eb4226910a301acae3b369fffc4a4899d6b02531e89fd4fe36a2cf0d93607ba470b50f7800")
+		_             = authSignature
+	)
+	makeAuth := func(test handshakeAuthTest) *authMsgV4 {
+		msg := &authMsgV4{Version: test.wantVersion, Rest: test.wantRest, gotPlain: test.isPlain}
+		copy(msg.Signature[:], authSignature)
+		copy(msg.InitiatorPubkey[:], pubA)
+		copy(msg.Nonce[:], nonceA)
+		return msg
+	}
+	makeAck := func(test handshakeAckTest) *authRespV4 {
+		msg := &authRespV4{Version: test.wantVersion, Rest: test.wantRest}
+		copy(msg.RandomPubkey[:], ephPubB)
+		copy(msg.Nonce[:], nonceB)
+		return msg
+	}
+
+	// check auth msg parsing
+	for _, test := range eip8HandshakeAuthTests {
+		r := bytes.NewReader(unhex(test.input))
+		msg := new(authMsgV4)
+		ciphertext, err := readHandshakeMsg(msg, encAuthMsgLen, keyB, r)
+		if err != nil {
+			t.Errorf("error for input %x:\n  %v", unhex(test.input), err)
+			continue
+		}
+		if !bytes.Equal(ciphertext, unhex(test.input)) {
+			t.Errorf("wrong ciphertext for input %x:\n  %x", unhex(test.input), ciphertext)
+		}
+		want := makeAuth(test)
+		if !reflect.DeepEqual(msg, want) {
+			t.Errorf("wrong msg for input %x:\ngot %s\nwant %s", unhex(test.input), spew.Sdump(msg), spew.Sdump(want))
+		}
+	}
+
+	// check auth resp parsing
+	for _, test := range eip8HandshakeRespTests {
+		input := unhex(test.input)
+		r := bytes.NewReader(input)
+		msg := new(authRespV4)
+		ciphertext, err := readHandshakeMsg(msg, encAuthRespLen, keyA, r)
+		if err != nil {
+			t.Errorf("error for input %x:\n  %v", input, err)
+			continue
+		}
+		if !bytes.Equal(ciphertext, input) {
+			t.Errorf("wrong ciphertext for input %x:\n  %x", input, err)
+		}
+		want := makeAck(test)
+		if !reflect.DeepEqual(msg, want) {
+			t.Errorf("wrong msg for input %x:\ngot %s\nwant %s", input, spew.Sdump(msg), spew.Sdump(want))
+		}
+	}
+
+	// check derivation for (Auth₂, Ack₂) on recipient side
+	var (
+		hs = &encHandshake{
+			initiator:     false,
+			respNonce:     nonceB,
+			randomPrivKey: ecies.ImportECDSA(ephB),
+		}
+		authCiphertext     = unhex(eip8HandshakeAuthTests[1].input)
+		authRespCiphertext = unhex(eip8HandshakeRespTests[1].input)
+		authMsg            = makeAuth(eip8HandshakeAuthTests[1])
+		wantAES            = unhex("80e8632c05fed6fc2a13b0f8d31a3cf645366239170ea067065aba8e28bac487")
+		wantMAC            = unhex("2ea74ec5dae199227dff1af715362700e989d889d7a493cb0639691efb8e5f98")
+		wantFooIngressHash = unhex("0c7ec6340062cc46f5e9f1e3cf86f8c8c403c5a0964f5df0ebd34a75ddc86db5")
+	)
+	if err := hs.handleAuthMsg(authMsg, keyB); err != nil {
+		t.Fatalf("handleAuthMsg: %v", err)
+	}
+	derived, err := hs.secrets(authCiphertext, authRespCiphertext)
+	if err != nil {
+		t.Fatalf("secrets: %v", err)
+	}
+	if !bytes.Equal(derived.AES, wantAES) {
+		t.Errorf("aes-secret mismatch:\ngot %x\nwant %x", derived.AES, wantAES)
+	}
+	if !bytes.Equal(derived.MAC, wantMAC) {
+		t.Errorf("mac-secret mismatch:\ngot %x\nwant %x", derived.MAC, wantMAC)
+	}
+	io.WriteString(derived.IngressMAC, "foo")
+	fooIngressHash := derived.IngressMAC.Sum(nil)
+	if !bytes.Equal(fooIngressHash, wantFooIngressHash) {
+		t.Errorf("ingress-mac('foo') mismatch:\ngot %x\nwant %x", fooIngressHash, wantFooIngressHash)
+	}
+}

rlp/decode.go

@@ -63,11 +63,12 @@ type Decoder interface {
 // must contain an element for each decoded field. Decode returns an
 // error if there are too few or too many elements.
 //
-// The decoding of struct fields honours one particular struct tag,
+// The decoding of struct fields honours two struct tags, "tail" and
-// "nil". This tag applies to pointer-typed fields and changes the
+// "nil". For an explanation of "tail", see the example.
+// The "nil" tag applies to pointer-typed fields and changes the
 // decoding rules for the field such that input values of size zero
-// decode as a nil pointer. This tag can be useful when decoding recursive
+// decode as a nil pointer. This tag can be useful when decoding
-// types.
+// recursive types.
 //
 //     type StructWithEmptyOK struct {
 //         Foo *[20]byte `rlp:"nil"`
@@ -190,7 +191,7 @@ func makeDecoder(typ reflect.Type, tags tags) (dec decoder, err error) {
 	case kind == reflect.String:
 		return decodeString, nil
 	case kind == reflect.Slice || kind == reflect.Array:
-		return makeListDecoder(typ)
+		return makeListDecoder(typ, tags)
 	case kind == reflect.Struct:
 		return makeStructDecoder(typ)
 	case kind == reflect.Ptr:
@@ -264,7 +265,7 @@ func decodeBigInt(s *Stream, val reflect.Value) error {
 	return nil
 }
 
-func makeListDecoder(typ reflect.Type) (decoder, error) {
+func makeListDecoder(typ reflect.Type, tag tags) (decoder, error) {
 	etype := typ.Elem()
 	if etype.Kind() == reflect.Uint8 && !reflect.PtrTo(etype).Implements(decoderInterface) {
 		if typ.Kind() == reflect.Array {
@@ -277,15 +278,26 @@ func makeListDecoder(typ reflect.Type) (decoder, error) {
 	if err != nil {
 		return nil, err
 	}
-
+	var dec decoder
-	isArray := typ.Kind() == reflect.Array
+	switch {
-	return func(s *Stream, val reflect.Value) error {
+	case typ.Kind() == reflect.Array:
-		if isArray {
+		dec = func(s *Stream, val reflect.Value) error {
 			return decodeListArray(s, val, etypeinfo.decoder)
-		} else {
+		}
+	case tag.tail:
+		// A slice with "tail" tag can occur as the last field
+		// of a struct and is upposed to swallow all remaining
+		// list elements. The struct decoder already called s.List,
+		// proceed directly to decoding the elements.
+		dec = func(s *Stream, val reflect.Value) error {
+			return decodeSliceElems(s, val, etypeinfo.decoder)
+		}
+	default:
+		dec = func(s *Stream, val reflect.Value) error {
 			return decodeListSlice(s, val, etypeinfo.decoder)
 		}
-	}, nil
+	}
+	return dec, nil
 }
 
 func decodeListSlice(s *Stream, val reflect.Value, elemdec decoder) error {
@@ -297,7 +309,13 @@ func decodeListSlice(s *Stream, val reflect.Value, elemdec decoder) error {
 		val.Set(reflect.MakeSlice(val.Type(), 0, 0))
 		return s.ListEnd()
 	}
+	if err := decodeSliceElems(s, val, elemdec); err != nil {
+		return err
+	}
+	return s.ListEnd()
+}
 
+func decodeSliceElems(s *Stream, val reflect.Value, elemdec decoder) error {
 	i := 0
 	for ; ; i++ {
 		// grow slice if necessary
@@ -323,12 +341,11 @@ func decodeListSlice(s *Stream, val reflect.Value, elemdec decoder) error {
 	if i < val.Len() {
 		val.SetLen(i)
 	}
-	return s.ListEnd()
+	return nil
 }
 
 func decodeListArray(s *Stream, val reflect.Value, elemdec decoder) error {
-	_, err := s.List()
+	if _, err := s.List(); err != nil {
-	if err != nil {
 		return wrapStreamError(err, val.Type())
 	}
 	vlen := val.Len()
@@ -398,11 +415,11 @@ func makeStructDecoder(typ reflect.Type) (decoder, error) {
 		return nil, err
 	}
 	dec := func(s *Stream, val reflect.Value) (err error) {
-		if _, err = s.List(); err != nil {
+		if _, err := s.List(); err != nil {
 			return wrapStreamError(err, typ)
 		}
 		for _, f := range fields {
-			err = f.info.decoder(s, val.Field(f.index))
+			err := f.info.decoder(s, val.Field(f.index))
 			if err == EOL {
 				return &decodeError{msg: "too few elements", typ: typ}
 			} else if err != nil {

rlp/decode_tail_test.go

@@ -0,0 +1,33 @@
+package rlp
+
+import (
+	"bytes"
+	"fmt"
+)
+
+type structWithTail struct {
+	A, B uint
+	C    []uint `rlp:"tail"`
+}
+
+func ExampleDecode_structTagTail() {
+	// In this example, the "tail" struct tag is used to decode lists of
+	// differing length into a struct.
+	var val structWithTail
+
+	err := Decode(bytes.NewReader([]byte{0xC4, 0x01, 0x02, 0x03, 0x04}), &val)
+	fmt.Printf("with 4 elements: err=%v val=%v\n", err, val)
+
+	err = Decode(bytes.NewReader([]byte{0xC6, 0x01, 0x02, 0x03, 0x04, 0x05, 0x06}), &val)
+	fmt.Printf("with 6 elements: err=%v val=%v\n", err, val)
+
+	// Note that at least two list elements must be present to
+	// fill fields A and B:
+	err = Decode(bytes.NewReader([]byte{0xC1, 0x01}), &val)
+	fmt.Printf("with 1 element: err=%q\n", err)
+
+	// Output:
+	// with 4 elements: err=<nil> val={1 2 [3 4]}
+	// with 6 elements: err=<nil> val={1 2 [3 4 5 6]}
+	// with 1 element: err="rlp: too few elements for rlp.structWithTail"
+}

rlp/decode_test.go

@@ -312,6 +312,26 @@ type recstruct struct {
 	Child *recstruct `rlp:"nil"`
 }
 
+type invalidTail1 struct {
+	A uint `rlp:"tail"`
+	B string
+}
+
+type invalidTail2 struct {
+	A uint
+	B string `rlp:"tail"`
+}
+
+type tailRaw struct {
+	A    uint
+	Tail []RawValue `rlp:"tail"`
+}
+
+type tailUint struct {
+	A    uint
+	Tail []uint `rlp:"tail"`
+}
+
 var (
 	veryBigInt = big.NewInt(0).Add(
 		big.NewInt(0).Lsh(big.NewInt(0xFFFFFFFFFFFFFF), 16),
@@ -437,6 +457,38 @@ var decodeTests = []decodeTest{
 		ptr:   new(recstruct),
 		error: "rlp: expected input string or byte for uint, decoding into (rlp.recstruct).Child.I",
 	},
+	{
+		input: "C0",
+		ptr:   new(invalidTail1),
+		error: "rlp: invalid struct tag \"tail\" for rlp.invalidTail1.A (must be on last field)",
+	},
+	{
+		input: "C0",
+		ptr:   new(invalidTail2),
+		error: "rlp: invalid struct tag \"tail\" for rlp.invalidTail2.B (field type is not slice)",
+	},
+	{
+		input: "C50102C20102",
+		ptr:   new(tailUint),
+		error: "rlp: expected input string or byte for uint, decoding into (rlp.tailUint).Tail[1]",
+	},
+
+	// struct tag "tail"
+	{
+		input: "C3010203",
+		ptr:   new(tailRaw),
+		value: tailRaw{A: 1, Tail: []RawValue{unhex("02"), unhex("03")}},
+	},
+	{
+		input: "C20102",
+		ptr:   new(tailRaw),
+		value: tailRaw{A: 1, Tail: []RawValue{unhex("02")}},
+	},
+	{
+		input: "C101",
+		ptr:   new(tailRaw),
+		value: tailRaw{A: 1, Tail: []RawValue{}},
+	},
 
 	// RawValue
 	{input: "01", ptr: new(RawValue), value: RawValue(unhex("01"))},

rlp/encode.go

@@ -345,7 +345,7 @@ var (
 )
 
 // makeWriter creates a writer function for the given type.
-func makeWriter(typ reflect.Type) (writer, error) {
+func makeWriter(typ reflect.Type, ts tags) (writer, error) {
 	kind := typ.Kind()
 	switch {
 	case typ == rawValueType:
@@ -371,7 +371,7 @@ func makeWriter(typ reflect.Type) (writer, error) {
 	case kind == reflect.Array && isByte(typ.Elem()):
 		return writeByteArray, nil
 	case kind == reflect.Slice || kind == reflect.Array:
-		return makeSliceWriter(typ)
+		return makeSliceWriter(typ, ts)
 	case kind == reflect.Struct:
 		return makeStructWriter(typ)
 	case kind == reflect.Ptr:
@@ -507,20 +507,21 @@ func writeInterface(val reflect.Value, w *encbuf) error {
 	return ti.writer(eval, w)
 }
 
-func makeSliceWriter(typ reflect.Type) (writer, error) {
+func makeSliceWriter(typ reflect.Type, ts tags) (writer, error) {
 	etypeinfo, err := cachedTypeInfo1(typ.Elem(), tags{})
 	if err != nil {
 		return nil, err
 	}
 	writer := func(val reflect.Value, w *encbuf) error {
-		lh := w.list()
+		if !ts.tail {
+			defer w.listEnd(w.list())
+		}
 		vlen := val.Len()
 		for i := 0; i < vlen; i++ {
 			if err := etypeinfo.writer(val.Index(i), w); err != nil {
 				return err
 			}
 		}
-		w.listEnd(lh)
 		return nil
 	}
 	return writer, nil

rlp/encode_test.go

@@ -214,6 +214,10 @@ var encTests = []encTest{
 	{val: simplestruct{A: 3, B: "foo"}, output: "C50383666F6F"},
 	{val: &recstruct{5, nil}, output: "C205C0"},
 	{val: &recstruct{5, &recstruct{4, &recstruct{3, nil}}}, output: "C605C404C203C0"},
+	{val: &tailRaw{A: 1, Tail: []RawValue{unhex("02"), unhex("03")}}, output: "C3010203"},
+	{val: &tailRaw{A: 1, Tail: []RawValue{unhex("02")}}, output: "C20102"},
+	{val: &tailRaw{A: 1, Tail: []RawValue{}}, output: "C101"},
+	{val: &tailRaw{A: 1, Tail: nil}, output: "C101"},
 
 	// nil
 	{val: (*uint)(nil), output: "80"},

rlp/typecache.go

@@ -17,7 +17,9 @@
 package rlp
 
 import (
+	"fmt"
 	"reflect"
+	"strings"
 	"sync"
 )
 
@@ -33,7 +35,13 @@ type typeinfo struct {
 
 // represents struct tags
 type tags struct {
+	// rlp:"nil" controls whether empty input results in a nil pointer.
 	nilOK bool
+
+	// rlp:"tail" controls whether this field swallows additional list
+	// elements. It can only be set for the last field, which must be
+	// of slice type.
+	tail bool
 }
 
 type typekey struct {
@@ -89,7 +97,10 @@ type field struct {
 func structFields(typ reflect.Type) (fields []field, err error) {
 	for i := 0; i < typ.NumField(); i++ {
 		if f := typ.Field(i); f.PkgPath == "" { // exported
-			tags := parseStructTag(f.Tag.Get("rlp"))
+			tags, err := parseStructTag(typ, i)
+			if err != nil {
+				return nil, err
+			}
 			info, err := cachedTypeInfo1(f.Type, tags)
 			if err != nil {
 				return nil, err
@@ -100,8 +111,27 @@ func structFields(typ reflect.Type) (fields []field, err error) {
 	return fields, nil
 }
 
-func parseStructTag(tag string) tags {
+func parseStructTag(typ reflect.Type, fi int) (tags, error) {
-	return tags{nilOK: tag == "nil"}
+	f := typ.Field(fi)
+	var ts tags
+	for _, t := range strings.Split(f.Tag.Get("rlp"), ",") {
+		switch t = strings.TrimSpace(t); t {
+		case "":
+		case "nil":
+			ts.nilOK = true
+		case "tail":
+			ts.tail = true
+			if fi != typ.NumField()-1 {
+				return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (must be on last field)`, typ, f.Name)
+			}
+			if f.Type.Kind() != reflect.Slice {
+				return ts, fmt.Errorf(`rlp: invalid struct tag "tail" for %v.%s (field type is not slice)`, typ, f.Name)
+			}
+		default:
+			return ts, fmt.Errorf("rlp: unknown struct tag %q on %v.%s", t, typ, f.Name)
+		}
+	}
+	return ts, nil
 }
 
 func genTypeInfo(typ reflect.Type, tags tags) (info *typeinfo, err error) {
@@ -109,7 +139,7 @@ func genTypeInfo(typ reflect.Type, tags tags) (info *typeinfo, err error) {
 	if info.decoder, err = makeDecoder(typ, tags); err != nil {
 		return nil, err
 	}
-	if info.writer, err = makeWriter(typ); err != nil {
+	if info.writer, err = makeWriter(typ, tags); err != nil {
 		return nil, err
 	}
 	return info, nil