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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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157
p2p/handshake.go
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@ -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"
)
@ -38,13 +40,23 @@ 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
Token []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
}
// protoHandshake is the RLP structure of the protocol handshake.
@ -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