From b855f671a508a7e8160cbdd27197ba83310b264c Mon Sep 17 00:00:00 2001
From: zelig <viktor.tron@gmail.com>
Date: Sun, 18 Jan 2015 23:53:45 +0000
Subject: [PATCH] rewrite to comply with latest spec - correct sizes for the
blocks : sec signature 65, ecies sklen 16, keylength 32 - added allocation to
Xor (should be optimized later) - no pubkey reader needed, just do with copy
- restructuring now into INITIATE, RESPOND, COMPLETE -> newSession
initialises the encryption/authentication layer - crypto identity can be part
of client identity, some initialisation when server created
---
p2p/crypto.go | 191 ++++++++++++++++++++++++++++++++++++--------------
1 file changed, 138 insertions(+), 53 deletions(-)
diff --git a/p2p/crypto.go b/p2p/crypto.go
index 9204fa9d0..6e3f360d9 100644
--- a/p2p/crypto.go
+++ b/p2p/crypto.go
@@ -1,11 +1,11 @@
package p2p
import (
- "bytes"
+ // "bytes"
"crypto/ecdsa"
"crypto/rand"
"fmt"
- "io"
+ // "io"
"github.com/ethereum/go-ethereum/crypto"
"github.com/obscuren/ecies"
@@ -13,21 +13,22 @@ import (
)
var (
- skLen int = 32 // ecies.MaxSharedKeyLength(pubKey) / 2
- sigLen int = 32 // elliptic S256
- pubKeyLen int = 32 // ECDSA
- msgLen int = sigLen + 1 + pubKeyLen + skLen // 97
+ sskLen int = 16 // ecies.MaxSharedKeyLength(pubKey) / 2
+ sigLen int = 65 // elliptic S256
+ keyLen int = 32 // ECDSA
+ msgLen int = sigLen + 3*keyLen + 1 // 162
+ resLen int = 65
)
-//, aesSecret, macSecret, egressMac, ingress
+// aesSecret, macSecret, egressMac, ingress
type secretRW struct {
aesSecret, macSecret, egressMac, ingressMac []byte
}
type cryptoId struct {
- prvKey *ecdsa.PrivateKey
- pubKey *ecdsa.PublicKey
- pubKeyR io.ReaderAt
+ prvKey *ecdsa.PrivateKey
+ pubKey *ecdsa.PublicKey
+ pubKeyDER []byte
}
func newCryptoId(id ClientIdentity) (self *cryptoId, err error) {
@@ -50,99 +51,181 @@ func newCryptoId(id ClientIdentity) (self *cryptoId, err error) {
// to be created at server init shared between peers and sessions
// for reuse, call wth ReadAt, no reset seek needed
}
- self.pubKeyR = bytes.NewReader(id.Pubkey())
+ self.pubKeyDER = id.Pubkey()
return
}
-//
-func (self *cryptoId) setupAuth(remotePubKeyDER, sessionToken []byte) (auth []byte, nonce []byte, sharedKnowledge []byte, err error) {
+// initAuth is called by peer if it initiated the connection
+func (self *cryptoId) initAuth(remotePubKeyDER, sessionToken []byte) (auth []byte, initNonce []byte, remotePubKey *ecdsa.PublicKey, err error) {
// session init, common to both parties
- var remotePubKey = crypto.ToECDSAPub(remotePubKeyDER)
+ remotePubKey = crypto.ToECDSAPub(remotePubKeyDER)
if remotePubKey == nil {
err = fmt.Errorf("invalid remote public key")
return
}
- var sharedSecret []byte
- // generate shared key from prv and remote pubkey
- sharedSecret, err = ecies.ImportECDSA(self.prvKey).GenerateShared(ecies.ImportECDSAPublic(remotePubKey), skLen, skLen)
- if err != nil {
- return
- }
- // check previous session token
+
+ var tokenFlag byte
if sessionToken == nil {
- err = fmt.Errorf("no session token for peer")
- return
+ // 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
+ if sessionToken, err = ecies.ImportECDSA(self.prvKey).GenerateShared(ecies.ImportECDSAPublic(remotePubKey), sskLen, sskLen); err != nil {
+ return
+ }
+ fmt.Printf("secret generated: %v %x", len(sessionToken), sessionToken)
+ // tokenFlag = 0x00 // redundant
+ } else {
+ // for known peers, we use stored token from the previous session
+ tokenFlag = 0x01
}
- // allocate msgLen long message
+
+ //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)
+ // allocate msgLen long message,
var msg []byte = make([]byte, msgLen)
- // generate skLen long nonce at the end
- nonce = msg[msgLen-skLen:]
- if _, err = rand.Read(nonce); err != nil {
+ // generate sskLen long nonce
+ initNonce = msg[msgLen-keyLen-1 : msgLen-1]
+ // nonce = msg[msgLen-sskLen-1 : msgLen-1]
+ if _, err = rand.Read(initNonce); err != nil {
return
}
// create known message
- // should use
- // cipher.xorBytes from crypto/cipher/xor.go for fast xor
- sharedKnowledge = Xor(sharedSecret, sessionToken)
- var signedMsg = Xor(sharedKnowledge, nonce)
+ // ecdh-shared-secret^nonce for new peers
+ // token^nonce for old peers
+ var sharedSecret = Xor(sessionToken, initNonce)
// generate random keypair to use for signing
var ecdsaRandomPrvKey *ecdsa.PrivateKey
if ecdsaRandomPrvKey, err = crypto.GenerateKey(); err != nil {
return
}
- // var ecdsaRandomPubKey *ecdsa.PublicKey
- // ecdsaRandomPubKey= &ecdsaRandomPrvKey.PublicKey
-
- // message known to both parties ecdh-shared-secret^nonce^token
+ // sign shared secret (message known to both parties): shared-secret
var signature []byte
- // signature = sign(ecdhe-random, ecdh-shared-secret^nonce^token)
+ // signature = sign(ecdhe-random, shared-secret)
// uses secp256k1.Sign
- if signature, err = crypto.Sign(signedMsg, ecdsaRandomPrvKey); err != nil {
+ if signature, err = crypto.Sign(sharedSecret, ecdsaRandomPrvKey); err != nil {
return
}
- // msg = signature || 0x80 || pubk || nonce
- copy(msg, signature)
- msg[sigLen] = 0x80
- self.pubKeyR.ReadAt(msg[sigLen+1:], int64(pubKeyLen)) // gives pubKeyLen, io.EOF (since we dont read onto the nonce)
+ fmt.Printf("signature generated: %v %x", len(signature), signature)
+ // message
+ // signed-shared-secret || H(ecdhe-random-pubk) || pubk || nonce || 0x0
+ copy(msg, signature) // copy signed-shared-secret
+ // H(ecdhe-random-pubk)
+ copy(msg[sigLen:sigLen+keyLen], crypto.Sha3(crypto.FromECDSAPub(&ecdsaRandomPrvKey.PublicKey)))
+ // pubkey copied to the correct segment.
+ copy(msg[sigLen+keyLen:sigLen+2*keyLen], self.pubKeyDER)
+ // nonce is already in the slice
+ // stick tokenFlag byte to the end
+ msg[msgLen-1] = tokenFlag
+
+ fmt.Printf("plaintext message generated: %v %x", len(msg), msg)
+
+ // encrypt using remote-pubk
// auth = eciesEncrypt(remote-pubk, msg)
+
if auth, err = crypto.Encrypt(remotePubKey, msg); err != nil {
return
}
+ fmt.Printf("encrypted message generated: %v %x\n used pubkey: %x\n", len(auth), auth, crypto.FromECDSAPub(remotePubKey))
+
return
}
-func (self *cryptoId) verifyAuth(auth, nonce, sharedKnowledge []byte) (sessionToken []byte, rw *secretRW, err error) {
+// verifyAuth is called by peer if it accepted (but not initiated) the connection
+func (self *cryptoId) verifyAuth(auth, sharedSecret []byte, remotePubKey *ecdsa.PublicKey) (authResp []byte, respNonce []byte, initNonce []byte, remoteRandomPubKey *ecdsa.PublicKey, err error) {
var msg []byte
+ fmt.Printf("encrypted message received: %v %x\n used pubkey: %x\n", len(auth), auth, crypto.FromECDSAPub(self.pubKey))
// they prove that msg is meant for me,
// I prove I possess private key if i can read it
if msg, err = crypto.Decrypt(self.prvKey, auth); err != nil {
return
}
- var remoteNonce []byte = msg[msgLen-skLen:]
- // I prove that i possess prv key (to derive shared secret, and read nonce off encrypted msg) and that I posessed the earlier one , our shared history
- // they prove they possess their private key to derive the same shared secret, plus the same shared history (previous session token)
- var signedMsg = Xor(sharedKnowledge, remoteNonce)
+ // var remoteNonce []byte = msg[msgLen-skLen-1 : msgLen-1]
+ initNonce = msg[msgLen-keyLen-1 : msgLen-1]
+ // I prove that i own prv key (to derive shared secret, and read nonce off encrypted msg) and that I own shared secret
+ // they prove they own the private key belonging to ecdhe-random-pubk
+ var signedMsg = Xor(sharedSecret, initNonce)
var remoteRandomPubKeyDER []byte
- if remoteRandomPubKeyDER, err = secp256k1.RecoverPubkey(signedMsg, msg[:32]); err != nil {
+ if remoteRandomPubKeyDER, err = secp256k1.RecoverPubkey(signedMsg, msg[:sigLen]); err != nil {
return
}
- var remoteRandomPubKey = crypto.ToECDSAPub(remoteRandomPubKeyDER)
+ remoteRandomPubKey = crypto.ToECDSAPub(remoteRandomPubKeyDER)
if remoteRandomPubKey == nil {
err = fmt.Errorf("invalid remote public key")
return
}
- // 3) Now we can trust ecdhe-random-pubk to derive keys
+
+ var resp = make([]byte, 2*keyLen+1)
+ // generate sskLen long nonce
+ respNonce = msg[msgLen-keyLen-1 : msgLen-1]
+ if _, err = rand.Read(respNonce); err != nil {
+ return
+ }
+ // generate random keypair
+ var ecdsaRandomPrvKey *ecdsa.PrivateKey
+ if ecdsaRandomPrvKey, err = crypto.GenerateKey(); err != nil {
+ return
+ }
+ // var ecdsaRandomPubKey *ecdsa.PublicKey
+ // ecdsaRandomPubKey= &ecdsaRandomPrvKey.PublicKey
+
+ // message
+ // E(remote-pubk, ecdhe-random-pubk || nonce || 0x0)
+ copy(resp[:keyLen], crypto.FromECDSAPub(&ecdsaRandomPrvKey.PublicKey))
+ // pubkey copied to the correct segment.
+ copy(resp[keyLen:2*keyLen], self.pubKeyDER)
+ // nonce is already in the slice
+ // stick tokenFlag byte to the end
+ var tokenFlag byte
+ if sharedSecret == nil {
+ } else {
+ // for known peers, we use stored token from the previous session
+ tokenFlag = 0x01
+ }
+ resp[resLen] = tokenFlag
+
+ // encrypt using remote-pubk
+ // auth = eciesEncrypt(remote-pubk, msg)
+ // why not encrypt with ecdhe-random-remote
+ if authResp, err = crypto.Encrypt(remotePubKey, resp); err != nil {
+ return
+ }
+ return
+}
+
+func (self *cryptoId) verifyAuthResp(auth []byte) (respNonce []byte, remoteRandomPubKey *ecdsa.PublicKey, tokenFlag bool, err error) {
+ var msg []byte
+ // they prove that msg is meant for me,
+ // I prove I possess private key if i can read it
+ if msg, err = crypto.Decrypt(self.prvKey, auth); err != nil {
+ return
+ }
+
+ respNonce = msg[resLen-keyLen-1 : resLen-1]
+ var remoteRandomPubKeyDER = msg[:keyLen]
+ remoteRandomPubKey = crypto.ToECDSAPub(remoteRandomPubKeyDER)
+ if remoteRandomPubKey == nil {
+ err = fmt.Errorf("invalid ecdh random remote public key")
+ return
+ }
+ if msg[resLen-1] == 0x01 {
+ tokenFlag = true
+ }
+ return
+}
+
+func (self *cryptoId) newSession(initNonce, respNonce, auth []byte, remoteRandomPubKey *ecdsa.PublicKey) (sessionToken []byte, rw *secretRW, err error) {
+ // 3) Now we can trust ecdhe-random-pubk to derive new keys
//ecdhe-shared-secret = ecdh.agree(ecdhe-random, remote-ecdhe-random-pubk)
var dhSharedSecret []byte
- dhSharedSecret, err = ecies.ImportECDSA(self.prvKey).GenerateShared(ecies.ImportECDSAPublic(remoteRandomPubKey), skLen, skLen)
+ dhSharedSecret, err = ecies.ImportECDSA(self.prvKey).GenerateShared(ecies.ImportECDSAPublic(remoteRandomPubKey), sskLen, sskLen)
if err != nil {
return
}
// shared-secret = crypto.Sha3(ecdhe-shared-secret || crypto.Sha3(nonce || initiator-nonce))
- var sharedSecret []byte = crypto.Sha3(append(dhSharedSecret, crypto.Sha3(append(nonce, remoteNonce...))...))
+ var sharedSecret = crypto.Sha3(append(dhSharedSecret, crypto.Sha3(append(respNonce, initNonce...))...))
// token = crypto.Sha3(shared-secret)
sessionToken = crypto.Sha3(sharedSecret)
// aes-secret = crypto.Sha3(ecdhe-shared-secret || shared-secret)
@@ -152,10 +235,10 @@ func (self *cryptoId) verifyAuth(auth, nonce, sharedKnowledge []byte) (sessionTo
var macSecret = crypto.Sha3(append(dhSharedSecret, aesSecret...))
// # destroy ecdhe-shared-secret
// egress-mac = crypto.Sha3(mac-secret^nonce || auth)
- var egressMac = crypto.Sha3(append(Xor(macSecret, nonce), auth...))
+ var egressMac = crypto.Sha3(append(Xor(macSecret, respNonce), auth...))
// # destroy nonce
// ingress-mac = crypto.Sha3(mac-secret^initiator-nonce || auth),
- var ingressMac = crypto.Sha3(append(Xor(macSecret, remoteNonce), auth...))
+ var ingressMac = crypto.Sha3(append(Xor(macSecret, initNonce), auth...))
// # destroy remote-nonce
rw = &secretRW{
aesSecret: aesSecret,
@@ -166,7 +249,9 @@ func (self *cryptoId) verifyAuth(auth, nonce, sharedKnowledge []byte) (sessionTo
return
}
+// should use cipher.xorBytes from crypto/cipher/xor.go for fast xor
func Xor(one, other []byte) (xor []byte) {
+ xor = make([]byte, len(one))
for i := 0; i < len(one); i++ {
xor[i] = one[i] ^ other[i]
}
--
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