diff --git a/p2p/rlpx.go b/p2p/rlpx.go index fd43f565e4..aaa7338547 100644 --- a/p2p/rlpx.go +++ b/p2p/rlpx.go @@ -267,6 +267,10 @@ func initiatorEncHandshake(conn io.ReadWriter, prv *ecdsa.PrivateKey, remoteID d } func newInitiatorHandshake(remoteID discover.NodeID) (*encHandshake, error) { + rpub, err := remoteID.Pubkey() + if err != nil { + return nil, fmt.Errorf("bad remoteID: %v", err) + } // generate random initiator nonce n := make([]byte, shaLen) if _, err := rand.Read(n); err != nil { @@ -277,10 +281,6 @@ func newInitiatorHandshake(remoteID discover.NodeID) (*encHandshake, error) { if err != nil { return nil, err } - rpub, err := remoteID.Pubkey() - if err != nil { - return nil, fmt.Errorf("bad remoteID: %v", err) - } h := &encHandshake{ initiator: true, remoteID: remoteID, @@ -417,6 +417,14 @@ func decodeAuthMsg(prv *ecdsa.PrivateKey, token []byte, auth []byte) (*encHandsh 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 }