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p2p: encrypted and authenticated RLPx frame I/O

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This commit is contained in:
Felix Lange 2015-02-27 02:09:53 +00:00
parent 936dd0f3bc
commit 51e01cceca
4 changed files with 196 additions and 171 deletions
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155
p2p/handshake.go
View File

@ -5,12 +5,14 @@ import (
"crypto/rand"
"errors"
"fmt"
"hash"
"io"
"net"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/crypto/ecies"
"github.com/ethereum/go-ethereum/crypto/secp256k1"
"github.com/ethereum/go-ethereum/crypto/sha3"
"github.com/ethereum/go-ethereum/p2p/discover"
"github.com/ethereum/go-ethereum/rlp"
)
@ -38,12 +40,22 @@ func newConn(fd net.Conn, hs *protoHandshake) *conn {
return &conn{newFrameRW(fd, msgWriteTimeout), hs}
}
// encHandshake represents information about the remote end
// of a connection that is negotiated during the encryption handshake.
// encHandshake contains the state of the encryption handshake.
type encHandshake struct {
ID discover.NodeID
IngressMAC []byte
EgressMAC []byte
remoteID discover.NodeID
initiator bool
initNonce, respNonce []byte
dhSharedSecret []byte
randomPrivKey *ecdsa.PrivateKey
remoteRandomPub *ecdsa.PublicKey
}
// secrets represents the connection secrets
// which are negotiated during the encryption handshake.
type secrets struct {
RemoteID discover.NodeID
AES, MAC []byte
EgressMAC, IngressMAC hash.Hash
Token []byte
}
@ -56,6 +68,34 @@ type protoHandshake struct {
ID discover.NodeID
}
// 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 {
sharedSecret := crypto.Sha3(h.dhSharedSecret, crypto.Sha3(h.respNonce, h.initNonce))
aesSecret := crypto.Sha3(h.dhSharedSecret, sharedSecret)
s := secrets{
RemoteID: h.remoteID,
AES: aesSecret,
MAC: crypto.Sha3(h.dhSharedSecret, aesSecret),
Token: crypto.Sha3(sharedSecret),
}
// setup sha3 instances for the MACs
mac1 := sha3.NewKeccak256()
mac1.Write(xor(s.MAC, h.respNonce))
mac1.Write(auth)
mac2 := sha3.NewKeccak256()
mac2.Write(xor(s.MAC, h.initNonce))
mac2.Write(authResp)
if h.initiator {
s.EgressMAC, s.IngressMAC = mac1, mac2
} else {
s.EgressMAC, s.IngressMAC = mac2, mac1
}
return s
}
// setupConn starts a protocol session on the given connection.
// It runs the encryption handshake and the protocol handshake.
// If dial is non-nil, the connection the local node is the initiator.
@ -68,36 +108,47 @@ func setupConn(fd net.Conn, prv *ecdsa.PrivateKey, our *protoHandshake, dial *di
}
func setupInboundConn(fd net.Conn, prv *ecdsa.PrivateKey, our *protoHandshake) (*conn, error) {
// var remotePubkey []byte
// sessionToken, remotePubkey, err = inboundEncHandshake(fd, prv, nil)
// copy(remoteID[:], remotePubkey)
secrets, err := inboundEncHandshake(fd, prv, nil)
if err != nil {
return nil, fmt.Errorf("encryption handshake failed: %v", err)
}
rw := newFrameRW(fd, msgWriteTimeout)
rhs, err := readProtocolHandshake(rw, our)
// Run the protocol handshake using authenticated messages.
// TODO: move buffering setup here (out of newFrameRW)
phsrw := newRlpxFrameRW(fd, secrets)
rhs, err := readProtocolHandshake(phsrw, our)
if err != nil {
return nil, err
}
if err := writeProtocolHandshake(rw, our); err != nil {
if err := writeProtocolHandshake(phsrw, our); err != nil {
return nil, fmt.Errorf("protocol write error: %v", err)
}
rw := newFrameRW(fd, msgWriteTimeout)
return &conn{rw, rhs}, nil
}
func setupOutboundConn(fd net.Conn, prv *ecdsa.PrivateKey, our *protoHandshake, dial *discover.Node) (*conn, error) {
// remoteID = dial.ID
// sessionToken, err = outboundEncHandshake(fd, prv, remoteID[:], nil)
secrets, err := outboundEncHandshake(fd, prv, dial.ID[:], nil)
if err != nil {
return nil, fmt.Errorf("encryption handshake failed: %v", err)
}
rw := newFrameRW(fd, msgWriteTimeout)
if err := writeProtocolHandshake(rw, our); err != nil {
// Run the protocol handshake using authenticated messages.
// TODO: move buffering setup here (out of newFrameRW)
phsrw := newRlpxFrameRW(fd, secrets)
if err := writeProtocolHandshake(phsrw, our); err != nil {
return nil, fmt.Errorf("protocol write error: %v", err)
}
rhs, err := readProtocolHandshake(rw, our)
rhs, err := readProtocolHandshake(phsrw, our)
if err != nil {
return nil, fmt.Errorf("protocol handshake read error: %v", err)
}
if rhs.ID != dial.ID {
return nil, errors.New("dialed node id mismatch")
}
rw := newFrameRW(fd, msgWriteTimeout)
return &conn{rw, rhs}, nil
}
@ -107,43 +158,48 @@ func setupOutboundConn(fd net.Conn, prv *ecdsa.PrivateKey, our *protoHandshake,
// privateKey is the local client's private key
// remotePublicKey is the remote peer's node ID
// sessionToken is the token from a previous session with this node.
func outboundEncHandshake(conn io.ReadWriter, prvKey *ecdsa.PrivateKey, remotePublicKey []byte, sessionToken []byte) (
newSessionToken []byte,
err error,
) {
func outboundEncHandshake(conn io.ReadWriter, prvKey *ecdsa.PrivateKey, remotePublicKey []byte, sessionToken []byte) (s secrets, err error) {
auth, initNonce, randomPrivKey, err := authMsg(prvKey, remotePublicKey, sessionToken)
if err != nil {
return nil, err
return s, err
}
if _, err = conn.Write(auth); err != nil {
return nil, err
return s, err
}
response := make([]byte, rHSLen)
if _, err = io.ReadFull(conn, response); err != nil {
return nil, err
return s, err
}
recNonce, remoteRandomPubKey, _, err := completeHandshake(response, prvKey)
if err != nil {
return nil, err
return s, err
}
return newSession(initNonce, recNonce, randomPrivKey, remoteRandomPubKey)
h := &encHandshake{
initiator: true,
initNonce: initNonce,
respNonce: recNonce,
randomPrivKey: randomPrivKey,
remoteRandomPub: remoteRandomPubKey,
}
copy(h.remoteID[:], remotePublicKey)
return h.secrets(auth, response), nil
}
// authMsg creates the initiator handshake.
// TODO: change all the names
func authMsg(prvKey *ecdsa.PrivateKey, remotePubKeyS, sessionToken []byte) (
auth, initNonce []byte,
randomPrvKey *ecdsa.PrivateKey,
err error,
) {
// session init, common to both parties
remotePubKey, err := importPublicKey(remotePubKeyS)
if err != nil {
return
}
var tokenFlag byte // = 0x00
var tokenFlag byte
if sessionToken == nil {
// no session token found means we need to generate shared secret.
// ecies shared secret is used as initial session token for new peers
@ -151,14 +207,13 @@ func authMsg(prvKey *ecdsa.PrivateKey, remotePubKeyS, sessionToken []byte) (
if sessionToken, err = ecies.ImportECDSA(prvKey).GenerateShared(ecies.ImportECDSAPublic(remotePubKey), sskLen, sskLen); err != nil {
return
}
// tokenFlag = 0x00 // redundant
} else {
// for known peers, we use stored token from the previous session
tokenFlag = 0x01
}
//E(remote-pubk, S(ecdhe-random, ecdh-shared-secret^nonce) || H(ecdhe-random-pubk) || pubk || nonce || 0x0)
// E(remote-pubk, S(ecdhe-random, token^nonce) || H(ecdhe-random-pubk) || pubk || nonce || 0x1)
//E(remote-pubk, S(ecdhe-random, sha3(ecdh-shared-secret^nonce)) || H(ecdhe-random-pubk) || pubk || nonce || 0x0)
// E(remote-pubk, S(ecdhe-random, sha3(token^nonce)) || H(ecdhe-random-pubk) || pubk || nonce || 0x1)
// allocate msgLen long message,
var msg []byte = make([]byte, authMsgLen)
initNonce = msg[authMsgLen-shaLen-1 : authMsgLen-1]
@ -242,27 +297,32 @@ func completeHandshake(auth []byte, prvKey *ecdsa.PrivateKey) (
//
// privateKey is the local client's private key
// sessionToken is the token from a previous session with this node.
func inboundEncHandshake(conn io.ReadWriter, prvKey *ecdsa.PrivateKey, sessionToken []byte) (
token, remotePubKey []byte,
err error,
) {
func inboundEncHandshake(conn io.ReadWriter, prvKey *ecdsa.PrivateKey, sessionToken []byte) (s secrets, err error) {
// we are listening connection. we are responders in the
// handshake. Extract info from the authentication. The initiator
// starts by sending us a handshake that we need to respond to. so
// we read auth message first, then respond.
auth := make([]byte, iHSLen)
if _, err := io.ReadFull(conn, auth); err != nil {
return nil, nil, err
return s, err
}
response, recNonce, initNonce, remotePubKey, randomPrivKey, remoteRandomPubKey, err := authResp(auth, sessionToken, prvKey)
if err != nil {
return nil, nil, err
return s, err
}
if _, err = conn.Write(response); err != nil {
return nil, nil, err
return s, err
}
token, err = newSession(initNonce, recNonce, randomPrivKey, remoteRandomPubKey)
return token, remotePubKey, err
h := &encHandshake{
initiator: false,
initNonce: initNonce,
respNonce: recNonce,
randomPrivKey: randomPrivKey,
remoteRandomPub: remoteRandomPubKey,
}
copy(h.remoteID[:], remotePubKey)
return h.secrets(auth, response), err
}
// authResp is called by peer if it accepted (but not
@ -349,23 +409,6 @@ func authResp(auth, sessionToken []byte, prvKey *ecdsa.PrivateKey) (
return
}
// newSession is called after the handshake is completed. The
// arguments are values negotiated in the handshake. The return value
// is a new session Token to be remembered for the next time we
// connect with this peer.
func newSession(initNonce, respNonce []byte, privKey *ecdsa.PrivateKey, remoteRandomPubKey *ecdsa.PublicKey) ([]byte, error) {
// 3) Now we can trust ecdhe-random-pubk to derive new keys
//ecdhe-shared-secret = ecdh.agree(ecdhe-random, remote-ecdhe-random-pubk)
pubKey := ecies.ImportECDSAPublic(remoteRandomPubKey)
dhSharedSecret, err := ecies.ImportECDSA(privKey).GenerateShared(pubKey, sskLen, sskLen)
if err != nil {
return nil, err
}
sharedSecret := crypto.Sha3(dhSharedSecret, crypto.Sha3(respNonce, initNonce))
sessionToken := crypto.Sha3(sharedSecret)
return sessionToken, nil
}
// importPublicKey unmarshals 512 bit public keys.
func importPublicKey(pubKey []byte) (pubKeyEC *ecdsa.PublicKey, err error) {
var pubKey65 []byte

100
p2p/handshake_test.go
View File

@ -2,8 +2,6 @@ package p2p
import (
"bytes"
"crypto/ecdsa"
"crypto/rand"
"net"
"reflect"
"testing"
@ -69,102 +67,46 @@ func TestSharedSecret(t *testing.T) {
}
}
func TestCryptoHandshake(t *testing.T) {
testCryptoHandshake(newkey(), newkey(), nil, t)
}
func TestCryptoHandshakeWithToken(t *testing.T) {
sessionToken := make([]byte, shaLen)
rand.Read(sessionToken)
testCryptoHandshake(newkey(), newkey(), sessionToken, t)
}
func testCryptoHandshake(prv0, prv1 *ecdsa.PrivateKey, sessionToken []byte, t *testing.T) {
var err error
// pub0 := &prv0.PublicKey
pub1 := &prv1.PublicKey
// pub0s := crypto.FromECDSAPub(pub0)
pub1s := crypto.FromECDSAPub(pub1)
// simulate handshake by feeding output to input
// initiator sends handshake 'auth'
auth, initNonce, randomPrivKey, err := authMsg(prv0, pub1s, sessionToken)
if err != nil {
t.Errorf("%v", err)
}
// t.Logf("-> %v", hexkey(auth))
// receiver reads auth and responds with response
response, remoteRecNonce, remoteInitNonce, _, remoteRandomPrivKey, remoteInitRandomPubKey, err := authResp(auth, sessionToken, prv1)
if err != nil {
t.Errorf("%v", err)
}
// t.Logf("<- %v\n", hexkey(response))
// initiator reads receiver's response and the key exchange completes
recNonce, remoteRandomPubKey, _, err := completeHandshake(response, prv0)
if err != nil {
t.Errorf("completeHandshake error: %v", err)
}
// now both parties should have the same session parameters
initSessionToken, err := newSession(initNonce, recNonce, randomPrivKey, remoteRandomPubKey)
if err != nil {
t.Errorf("newSession error: %v", err)
}
recSessionToken, err := newSession(remoteInitNonce, remoteRecNonce, remoteRandomPrivKey, remoteInitRandomPubKey)
if err != nil {
t.Errorf("newSession error: %v", err)
}
// fmt.Printf("\nauth (%v) %x\n\nresp (%v) %x\n\n", len(auth), auth, len(response), response)
// fmt.Printf("\nauth %x\ninitNonce %x\nresponse%x\nremoteRecNonce %x\nremoteInitNonce %x\nremoteRandomPubKey %x\nrecNonce %x\nremoteInitRandomPubKey %x\ninitSessionToken %x\n\n", auth, initNonce, response, remoteRecNonce, remoteInitNonce, remoteRandomPubKey, recNonce, remoteInitRandomPubKey, initSessionToken)
if !bytes.Equal(initNonce, remoteInitNonce) {
t.Errorf("nonces do not match")
}
if !bytes.Equal(recNonce, remoteRecNonce) {
t.Errorf("receiver nonces do not match")
}
if !bytes.Equal(initSessionToken, recSessionToken) {
t.Errorf("session tokens do not match")
}
}
func TestEncHandshake(t *testing.T) {
defer testlog(t).detach()
prv0, _ := crypto.GenerateKey()
prv1, _ := crypto.GenerateKey()
pub0s, _ := exportPublicKey(&prv0.PublicKey)
pub1s, _ := exportPublicKey(&prv1.PublicKey)
rw0, rw1 := net.Pipe()
tokens := make(chan []byte)
secrets := make(chan secrets)
go func() {
token, err := outboundEncHandshake(rw0, prv0, pub1s, nil)
pub1s, _ := exportPublicKey(&prv1.PublicKey)
s, err := outboundEncHandshake(rw0, prv0, pub1s, nil)
if err != nil {
t.Errorf("outbound side error: %v", err)
}
tokens <- token
id1 := discover.PubkeyID(&prv1.PublicKey)
if s.RemoteID != id1 {
t.Errorf("outbound side remote ID mismatch")
}
secrets <- s
}()
go func() {
token, remotePubkey, err := inboundEncHandshake(rw1, prv1, nil)
s, err := inboundEncHandshake(rw1, prv1, nil)
if err != nil {
t.Errorf("inbound side error: %v", err)
}
if !bytes.Equal(remotePubkey, pub0s) {
t.Errorf("inbound side returned wrong remote pubkey\n got: %x\n want: %x", remotePubkey, pub0s)
id0 := discover.PubkeyID(&prv0.PublicKey)
if s.RemoteID != id0 {
t.Errorf("inbound side remote ID mismatch")
}
tokens <- token
secrets <- s
}()
t1, t2 := <-tokens, <-tokens
if !bytes.Equal(t1, t2) {
t.Error("session token mismatch")
// get computed secrets from both sides
t1, t2 := <-secrets, <-secrets
// don't compare remote node IDs
t1.RemoteID, t2.RemoteID = discover.NodeID{}, discover.NodeID{}
// flip MACs on one of them so they compare equal
t1.EgressMAC, t1.IngressMAC = t1.IngressMAC, t1.EgressMAC
if !reflect.DeepEqual(t1, t2) {
t.Errorf("secrets mismatch:\n t1: %#v\n t2: %#v", t1, t2)
}
}

64
p2p/rlpx.go
View File

@ -13,24 +13,44 @@ import (
)
var (
// this is used in place of actual frame header data.
// TODO: replace this when Msg contains the protocol type code.
zeroHeader = []byte{0xC2, 0x80, 0x80}
// sixteen zero bytes
zero16 = make([]byte, 16)
)
type rlpxFrameRW struct {
conn io.ReadWriter
enc cipher.Stream
dec cipher.Stream
macCipher cipher.Block
egressMAC hash.Hash
ingressMAC hash.Hash
}
func newRlpxFrameRW(conn io.ReadWriter, macSecret []byte, egressMAC, ingressMAC hash.Hash) *rlpxFrameRW {
cipher, err := aes.NewCipher(macSecret)
func newRlpxFrameRW(conn io.ReadWriter, s secrets) *rlpxFrameRW {
macc, err := aes.NewCipher(s.MAC)
if err != nil {
panic("invalid macSecret: " + err.Error())
panic("invalid MAC secret: " + err.Error())
}
encc, err := aes.NewCipher(s.AES)
if err != nil {
panic("invalid AES secret: " + err.Error())
}
// we use an all-zeroes IV for AES because the key used
// for encryption is ephemeral.
iv := make([]byte, encc.BlockSize())
return &rlpxFrameRW{
conn: conn,
enc: cipher.NewCTR(encc, iv),
dec: cipher.NewCTR(encc, iv),
macCipher: macc,
egressMAC: s.EgressMAC,
ingressMAC: s.IngressMAC,
}
return &rlpxFrameRW{conn: conn, macCipher: cipher, egressMAC: egressMAC, ingressMAC: ingressMAC}
}
func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
@ -41,13 +61,14 @@ func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
fsize := uint32(len(ptype)) + msg.Size
putInt24(fsize, headbuf) // TODO: check overflow
copy(headbuf[3:], zeroHeader)
rw.enc.XORKeyStream(headbuf[:16], headbuf[:16]) // first half is now encrypted
copy(headbuf[16:], updateHeaderMAC(rw.egressMAC, rw.macCipher, headbuf[:16]))
if _, err := rw.conn.Write(headbuf); err != nil {
return err
}
// write frame, updating the egress MAC while writing to conn.
tee := io.MultiWriter(rw.conn, rw.egressMAC)
// write encrypted frame, updating the egress MAC while writing to conn.
tee := cipher.StreamWriter{S: rw.enc, W: io.MultiWriter(rw.conn, rw.egressMAC)}
if _, err := tee.Write(ptype); err != nil {
return err
}
@ -62,7 +83,8 @@ func (rw *rlpxFrameRW) WriteMsg(msg Msg) error {
// write packet-mac. egress MAC is up to date because
// frame content was written to it as well.
_, err := rw.conn.Write(rw.egressMAC.Sum(nil))
mac := updateHeaderMAC(rw.egressMAC, rw.macCipher, rw.egressMAC.Sum(nil))
_, err := rw.conn.Write(mac)
return err
}
@ -72,34 +94,40 @@ func (rw *rlpxFrameRW) ReadMsg() (msg Msg, err error) {
if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
return msg, err
}
fsize := readInt24(headbuf)
// ignore protocol type for now
// verify header mac
shouldMAC := updateHeaderMAC(rw.ingressMAC, rw.macCipher, headbuf[:16])
if !hmac.Equal(shouldMAC[:16], headbuf[16:]) {
return msg, errors.New("bad header MAC")
}
rw.dec.XORKeyStream(headbuf[:16], headbuf[:16]) // first half is now decrypted
fsize := readInt24(headbuf)
// ignore protocol type for now
// read the frame content
framebuf := make([]byte, fsize)
var rsize = fsize // frame size rounded up to 16 byte boundary
if padding := fsize % 16; padding > 0 {
rsize += 16 - padding
}
framebuf := make([]byte, rsize)
if _, err := io.ReadFull(rw.conn, framebuf); err != nil {
return msg, err
}
rw.ingressMAC.Write(framebuf)
if padding := fsize % 16; padding > 0 {
if _, err := io.CopyN(rw.ingressMAC, rw.conn, int64(16-padding)); err != nil {
return msg, err
}
}
// read and validate frame MAC. we can re-use headbuf for that.
rw.ingressMAC.Write(framebuf)
if _, err := io.ReadFull(rw.conn, headbuf); err != nil {
return msg, err
}
if !hmac.Equal(rw.ingressMAC.Sum(nil), headbuf) {
shouldMAC = updateHeaderMAC(rw.ingressMAC, rw.macCipher, rw.ingressMAC.Sum(nil))
if !hmac.Equal(shouldMAC, headbuf) {
return msg, errors.New("bad frame MAC")
}
// decrypt frame content
rw.dec.XORKeyStream(framebuf, framebuf)
// decode message code
content := bytes.NewReader(framebuf)
content := bytes.NewReader(framebuf[:fsize])
if err := rlp.Decode(content, &msg.Code); err != nil {
return msg, err
}

44
p2p/rlpx_test.go
View File

@ -16,14 +16,18 @@ import (
func TestRlpxFrameFake(t *testing.T) {
buf := new(bytes.Buffer)
secret := crypto.Sha3()
hash := fakeHash([]byte{1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1})
rw := newRlpxFrameRW(buf, secret, hash, hash)
rw := newRlpxFrameRW(buf, secrets{
AES: crypto.Sha3(),
MAC: crypto.Sha3(),
IngressMAC: hash,
EgressMAC: hash,
})
golden := unhex(`
000006C2808000000000000000000000
00828ddae471818bb0bfa6b551d1cb42
01010101010101010101010101010101
08C40102030400000000000000000000
ba628a4ba590cb43f7848f41c4382885
01010101010101010101010101010101
01010101010101010101010101010101
`)
@ -75,27 +79,35 @@ func unhex(str string) []byte {
func TestRlpxFrameRW(t *testing.T) {
var (
aesSecret = make([]byte, 16)
macSecret = make([]byte, 16)
egressMACinit = make([]byte, 32)
ingressMACinit = make([]byte, 32)
)
for _, s := range [][]byte{macSecret, egressMACinit, ingressMACinit} {
for _, s := range [][]byte{aesSecret, macSecret, egressMACinit, ingressMACinit} {
rand.Read(s)
}
conn := new(bytes.Buffer)
em1 := sha3.NewKeccak256()
em1.Write(egressMACinit)
im1 := sha3.NewKeccak256()
im1.Write(ingressMACinit)
rw1 := newRlpxFrameRW(conn, macSecret, em1, im1)
s1 := secrets{
AES: aesSecret,
MAC: macSecret,
EgressMAC: sha3.NewKeccak256(),
IngressMAC: sha3.NewKeccak256(),
}
s1.EgressMAC.Write(egressMACinit)
s1.IngressMAC.Write(ingressMACinit)
rw1 := newRlpxFrameRW(conn, s1)
em2 := sha3.NewKeccak256()
em2.Write(ingressMACinit)
im2 := sha3.NewKeccak256()
im2.Write(egressMACinit)
rw2 := newRlpxFrameRW(conn, macSecret, em2, im2)
s2 := secrets{
AES: aesSecret,
MAC: macSecret,
EgressMAC: sha3.NewKeccak256(),
IngressMAC: sha3.NewKeccak256(),
}
s2.EgressMAC.Write(ingressMACinit)
s2.IngressMAC.Write(egressMACinit)
rw2 := newRlpxFrameRW(conn, s2)
// send some messages
for i := 0; i < 10; i++ {