Created
April 7, 2018 17:14
-
-
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A patch for https://github.com/ethereum/devp2p/issues/32 (Author @govictor)
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--- go-ethereum-1.7.2/p2p/rlpx.go 2017-10-14 14:58:53.000000000 +0200 | |
+++ rlpx.go 2018-04-07 19:07:05.000000000 +0200 | |
@@ -173,17 +173,20 @@ | |
var ( | |
sec secrets | |
err error | |
+ initiator bool // A flag tracking if node is initiator of the handshakes | |
) | |
if dial == nil { | |
sec, err = receiverEncHandshake(t.fd, prv, nil) | |
+ initiator = false | |
} else { | |
sec, err = initiatorEncHandshake(t.fd, prv, dial.ID, nil) | |
+ initiator = true | |
} | |
if err != nil { | |
return discover.NodeID{}, err | |
} | |
t.wmu.Lock() | |
- t.rw = newRLPXFrameRW(t.fd, sec) | |
+ t.rw = newRLPXFrameRW(t.fd, sec, initiator) | |
t.wmu.Unlock() | |
return sec.RemoteID, nil | |
} | |
@@ -203,7 +206,7 @@ | |
// which are negotiated during the encryption handshake. | |
type secrets struct { | |
RemoteID discover.NodeID | |
- AES, MAC []byte | |
+ AES, AES2, MAC []byte | |
EgressMAC, IngressMAC hash.Hash | |
Token []byte | |
} | |
@@ -242,10 +245,12 @@ | |
// derive base secrets from ephemeral key agreement | |
sharedSecret := crypto.Keccak256(ecdheSecret, crypto.Keccak256(h.respNonce, h.initNonce)) | |
aesSecret := crypto.Keccak256(ecdheSecret, sharedSecret) | |
+ aesSecret2 := crypto.Keccak256(ecdheSecret, aesSecret) // derive a second secret for aes | |
s := secrets{ | |
RemoteID: h.remoteID, | |
AES: aesSecret, | |
- MAC: crypto.Keccak256(ecdheSecret, aesSecret), | |
+ AES2: aesSecret2, | |
+ MAC: crypto.Keccak256(ecdheSecret, aesSecret2), // derive mac secret from second aes secret | |
} | |
// setup sha3 instances for the MACs | |
@@ -569,22 +574,38 @@ | |
snappy bool | |
} | |
-func newRLPXFrameRW(conn io.ReadWriter, s secrets) *rlpxFrameRW { | |
+func newRLPXFrameRW(conn io.ReadWriter, s secrets, initiator bool) *rlpxFrameRW { | |
macc, err := aes.NewCipher(s.MAC) | |
if err != nil { | |
panic("invalid MAC secret: " + err.Error()) | |
} | |
- encc, err := aes.NewCipher(s.AES) | |
+ // initializes aes keys according to role played by node during the handshake | |
+ var enccKey, deccKey []byte | |
+ if initiator { | |
+ enccKey = s.AES | |
+ deccKey = s.AES2 | |
+ } else { | |
+ enccKey = s.AES2 | |
+ deccKey = s.AES | |
+ } | |
+ // create 2 cyphers | |
+ encc, err := aes.NewCipher(enccKey) | |
+ if err != nil { | |
+ panic("invalid AES secret: " + err.Error()) | |
+ } | |
+ decc, err := aes.NewCipher(deccKey) | |
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()) | |
+ enccIv := make([]byte, encc.BlockSize()) | |
+ deccIv := make([]byte, decc.BlockSize()) | |
+ | |
return &rlpxFrameRW{ | |
conn: conn, | |
- enc: cipher.NewCTR(encc, iv), | |
- dec: cipher.NewCTR(encc, iv), | |
+ enc: cipher.NewCTR(encc, enccIv), | |
+ dec: cipher.NewCTR(decc, deccIv), | |
macCipher: macc, | |
egressMAC: s.EgressMAC, | |
ingressMAC: s.IngressMAC, |
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