cerc-io/plugeth
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rewrite to comply with latest spec

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- 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
This commit is contained in:
zelig 2015-01-18 23:53:45 +00:00 committed by Felix Lange
parent 4e52adb84a
commit b855f671a5
1 changed files with 143 additions and 58 deletions
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201
p2p/crypto.go
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@ -1,11 +1,11 @@
package p2p package p2p
import ( import (
"bytes" // "bytes"
"crypto/ecdsa" "crypto/ecdsa"
"crypto/rand" "crypto/rand"
"fmt" "fmt"
"io" // "io"
"github.com/ethereum/go-ethereum/crypto" "github.com/ethereum/go-ethereum/crypto"
"github.com/obscuren/ecies" "github.com/obscuren/ecies"
@ -13,21 +13,22 @@ import (
) )
var ( var (
skLen int = 32 // ecies.MaxSharedKeyLength(pubKey) / 2 sskLen int = 16 // ecies.MaxSharedKeyLength(pubKey) / 2
sigLen int = 32 // elliptic S256 sigLen int = 65 // elliptic S256
pubKeyLen int = 32 // ECDSA keyLen int = 32 // ECDSA
msgLen int = sigLen + 1 + pubKeyLen + skLen // 97 msgLen int = sigLen + 3*keyLen + 1 // 162
resLen int = 65
) )
//, aesSecret, macSecret, egressMac, ingress // aesSecret, macSecret, egressMac, ingress
type secretRW struct { type secretRW struct {
aesSecret, macSecret, egressMac, ingressMac []byte aesSecret, macSecret, egressMac, ingressMac []byte
} }
type cryptoId struct { type cryptoId struct {
prvKey *ecdsa.PrivateKey prvKey *ecdsa.PrivateKey
pubKey *ecdsa.PublicKey pubKey *ecdsa.PublicKey
pubKeyR io.ReaderAt pubKeyDER []byte
} }
func newCryptoId(id ClientIdentity) (self *cryptoId, err error) { func newCryptoId(id ClientIdentity) (self *cryptoId, err error) {
@ -50,70 +51,151 @@ func newCryptoId(id ClientIdentity) (self *cryptoId, err error) {
// to be created at server init shared between peers and sessions // to be created at server init shared between peers and sessions
// for reuse, call wth ReadAt, no reset seek needed // for reuse, call wth ReadAt, no reset seek needed
} }
self.pubKeyR = bytes.NewReader(id.Pubkey()) self.pubKeyDER = id.Pubkey()
return return
} }
// // initAuth is called by peer if it initiated the connection
func (self *cryptoId) setupAuth(remotePubKeyDER, sessionToken []byte) (auth []byte, nonce []byte, sharedKnowledge []byte, err error) { func (self *cryptoId) initAuth(remotePubKeyDER, sessionToken []byte) (auth []byte, initNonce []byte, remotePubKey *ecdsa.PublicKey, err error) {
// session init, common to both parties // session init, common to both parties
var remotePubKey = crypto.ToECDSAPub(remotePubKeyDER) remotePubKey = crypto.ToECDSAPub(remotePubKeyDER)
if remotePubKey == nil { if remotePubKey == nil {
err = fmt.Errorf("invalid remote public key") err = fmt.Errorf("invalid remote public key")
return return
} }
var sharedSecret []byte
// generate shared key from prv and remote pubkey var tokenFlag byte
sharedSecret, err = ecies.ImportECDSA(self.prvKey).GenerateShared(ecies.ImportECDSAPublic(remotePubKey), skLen, skLen)
if err != nil {
return
}
// check previous session token
if sessionToken == nil { if sessionToken == nil {
err = fmt.Errorf("no session token for peer") // no session token found means we need to generate shared secret.
return // 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) var msg []byte = make([]byte, msgLen)
// generate skLen long nonce at the end // generate sskLen long nonce
nonce = msg[msgLen-skLen:] initNonce = msg[msgLen-keyLen-1 : msgLen-1]
if _, err = rand.Read(nonce); err != nil { // nonce = msg[msgLen-sskLen-1 : msgLen-1]
if _, err = rand.Read(initNonce); err != nil {
return return
} }
// create known message // create known message
// should use // ecdh-shared-secret^nonce for new peers
// cipher.xorBytes from crypto/cipher/xor.go for fast xor // token^nonce for old peers
sharedKnowledge = Xor(sharedSecret, sessionToken) var sharedSecret = Xor(sessionToken, initNonce)
var signedMsg = Xor(sharedKnowledge, nonce)
// generate random keypair to use for signing // generate random keypair to use for signing
var ecdsaRandomPrvKey *ecdsa.PrivateKey var ecdsaRandomPrvKey *ecdsa.PrivateKey
if ecdsaRandomPrvKey, err = crypto.GenerateKey(); err != nil { if ecdsaRandomPrvKey, err = crypto.GenerateKey(); err != nil {
return return
} }
// sign shared secret (message known to both parties): shared-secret
var signature []byte
// signature = sign(ecdhe-random, shared-secret)
// uses secp256k1.Sign
if signature, err = crypto.Sign(sharedSecret, ecdsaRandomPrvKey); err != nil {
return
}
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
}
// 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-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[:sigLen]); err != nil {
return
}
remoteRandomPubKey = crypto.ToECDSAPub(remoteRandomPubKeyDER)
if remoteRandomPubKey == nil {
err = fmt.Errorf("invalid remote public key")
return
}
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 // var ecdsaRandomPubKey *ecdsa.PublicKey
// ecdsaRandomPubKey= &ecdsaRandomPrvKey.PublicKey // ecdsaRandomPubKey= &ecdsaRandomPrvKey.PublicKey
// message known to both parties ecdh-shared-secret^nonce^token // message
var signature []byte // E(remote-pubk, ecdhe-random-pubk || nonce || 0x0)
// signature = sign(ecdhe-random, ecdh-shared-secret^nonce^token) copy(resp[:keyLen], crypto.FromECDSAPub(&ecdsaRandomPrvKey.PublicKey))
// uses secp256k1.Sign // pubkey copied to the correct segment.
if signature, err = crypto.Sign(signedMsg, ecdsaRandomPrvKey); err != nil { copy(resp[keyLen:2*keyLen], self.pubKeyDER)
return // 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
} }
// msg = signature || 0x80 || pubk || nonce resp[resLen] = tokenFlag
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)
// encrypt using remote-pubk
// auth = eciesEncrypt(remote-pubk, msg) // auth = eciesEncrypt(remote-pubk, msg)
if auth, err = crypto.Encrypt(remotePubKey, msg); err != nil { // why not encrypt with ecdhe-random-remote
if authResp, err = crypto.Encrypt(remotePubKey, resp); err != nil {
return return
} }
return return
} }
func (self *cryptoId) verifyAuth(auth, nonce, sharedKnowledge []byte) (sessionToken []byte, rw *secretRW, err error) { func (self *cryptoId) verifyAuthResp(auth []byte) (respNonce []byte, remoteRandomPubKey *ecdsa.PublicKey, tokenFlag bool, err error) {
var msg []byte var msg []byte
// they prove that msg is meant for me, // they prove that msg is meant for me,
// I prove I possess private key if i can read it // I prove I possess private key if i can read it
@ -121,28 +203,29 @@ func (self *cryptoId) verifyAuth(auth, nonce, sharedKnowledge []byte) (sessionTo
return return
} }
var remoteNonce []byte = msg[msgLen-skLen:] respNonce = msg[resLen-keyLen-1 : resLen-1]
// 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 var remoteRandomPubKeyDER = msg[:keyLen]
// they prove they possess their private key to derive the same shared secret, plus the same shared history (previous session token) remoteRandomPubKey = crypto.ToECDSAPub(remoteRandomPubKeyDER)
var signedMsg = Xor(sharedKnowledge, remoteNonce)
var remoteRandomPubKeyDER []byte
if remoteRandomPubKeyDER, err = secp256k1.RecoverPubkey(signedMsg, msg[:32]); err != nil {
return
}
var remoteRandomPubKey = crypto.ToECDSAPub(remoteRandomPubKeyDER)
if remoteRandomPubKey == nil { if remoteRandomPubKey == nil {
err = fmt.Errorf("invalid remote public key") err = fmt.Errorf("invalid ecdh random remote public key")
return return
} }
// 3) Now we can trust ecdhe-random-pubk to derive keys 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) //ecdhe-shared-secret = ecdh.agree(ecdhe-random, remote-ecdhe-random-pubk)
var dhSharedSecret []byte 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 { if err != nil {
return return
} }
// shared-secret = crypto.Sha3(ecdhe-shared-secret || crypto.Sha3(nonce || initiator-nonce)) // 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) // token = crypto.Sha3(shared-secret)
sessionToken = crypto.Sha3(sharedSecret) sessionToken = crypto.Sha3(sharedSecret)
// aes-secret = crypto.Sha3(ecdhe-shared-secret || shared-secret) // 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...)) var macSecret = crypto.Sha3(append(dhSharedSecret, aesSecret...))
// # destroy ecdhe-shared-secret // # destroy ecdhe-shared-secret
// egress-mac = crypto.Sha3(mac-secret^nonce || auth) // 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 // # destroy nonce
// ingress-mac = crypto.Sha3(mac-secret^initiator-nonce || auth), // 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 // # destroy remote-nonce
rw = &secretRW{ rw = &secretRW{
aesSecret: aesSecret, aesSecret: aesSecret,
@ -166,7 +249,9 @@ func (self *cryptoId) verifyAuth(auth, nonce, sharedKnowledge []byte) (sessionTo
return return
} }
// should use cipher.xorBytes from crypto/cipher/xor.go for fast xor
func Xor(one, other []byte) (xor []byte) { func Xor(one, other []byte) (xor []byte) {
xor = make([]byte, len(one))
for i := 0; i < len(one); i++ { for i := 0; i < len(one); i++ {
xor[i] = one[i] ^ other[i] xor[i] = one[i] ^ other[i]
} }