You can not select more than 25 topics
Topics must start with a letter or number, can include dashes ('-') and can be up to 35 characters long.
348 lines
9.3 KiB
348 lines
9.3 KiB
// Uses nacl's secret_box to encrypt a net.Conn.
|
|
// It is (meant to be) an implementation of the STS protocol.
|
|
// Note we do not (yet) assume that a remote peer's pubkey
|
|
// is known ahead of time, and thus we are technically
|
|
// still vulnerable to MITM. (TODO!)
|
|
// See docs/sts-final.pdf for more info
|
|
package conn
|
|
|
|
import (
|
|
"bytes"
|
|
crand "crypto/rand"
|
|
"crypto/sha256"
|
|
"encoding/binary"
|
|
"errors"
|
|
"io"
|
|
"net"
|
|
"time"
|
|
|
|
"golang.org/x/crypto/nacl/box"
|
|
"golang.org/x/crypto/nacl/secretbox"
|
|
"golang.org/x/crypto/ripemd160"
|
|
|
|
"github.com/tendermint/go-crypto"
|
|
cmn "github.com/tendermint/tmlibs/common"
|
|
)
|
|
|
|
// 4 + 1024 == 1028 total frame size
|
|
const dataLenSize = 4
|
|
const dataMaxSize = 1024
|
|
const totalFrameSize = dataMaxSize + dataLenSize
|
|
const sealedFrameSize = totalFrameSize + secretbox.Overhead
|
|
|
|
// Implements net.Conn
|
|
type SecretConnection struct {
|
|
conn io.ReadWriteCloser
|
|
recvBuffer []byte
|
|
recvNonce *[24]byte
|
|
sendNonce *[24]byte
|
|
remPubKey crypto.PubKey
|
|
shrSecret *[32]byte // shared secret
|
|
}
|
|
|
|
// Performs handshake and returns a new authenticated SecretConnection.
|
|
// Returns nil if error in handshake.
|
|
// Caller should call conn.Close()
|
|
// See docs/sts-final.pdf for more information.
|
|
func MakeSecretConnection(conn io.ReadWriteCloser, locPrivKey crypto.PrivKey) (*SecretConnection, error) {
|
|
|
|
locPubKey := locPrivKey.PubKey()
|
|
|
|
// Generate ephemeral keys for perfect forward secrecy.
|
|
locEphPub, locEphPriv := genEphKeys()
|
|
|
|
// Write local ephemeral pubkey and receive one too.
|
|
// NOTE: every 32-byte string is accepted as a Curve25519 public key
|
|
// (see DJB's Curve25519 paper: http://cr.yp.to/ecdh/curve25519-20060209.pdf)
|
|
remEphPub, err := shareEphPubKey(conn, locEphPub)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
|
|
// Compute common shared secret.
|
|
shrSecret := computeSharedSecret(remEphPub, locEphPriv)
|
|
|
|
// Sort by lexical order.
|
|
loEphPub, hiEphPub := sort32(locEphPub, remEphPub)
|
|
|
|
// Check if the local ephemeral public key
|
|
// was the least, lexicographically sorted.
|
|
locIsLeast := bytes.Equal(locEphPub[:], loEphPub[:])
|
|
|
|
// Generate nonces to use for secretbox.
|
|
recvNonce, sendNonce := genNonces(loEphPub, hiEphPub, locIsLeast)
|
|
|
|
// Generate common challenge to sign.
|
|
challenge := genChallenge(loEphPub, hiEphPub)
|
|
|
|
// Construct SecretConnection.
|
|
sc := &SecretConnection{
|
|
conn: conn,
|
|
recvBuffer: nil,
|
|
recvNonce: recvNonce,
|
|
sendNonce: sendNonce,
|
|
shrSecret: shrSecret,
|
|
}
|
|
|
|
// Sign the challenge bytes for authentication.
|
|
locSignature := signChallenge(challenge, locPrivKey)
|
|
|
|
// Share (in secret) each other's pubkey & challenge signature
|
|
authSigMsg, err := shareAuthSignature(sc, locPubKey, locSignature)
|
|
if err != nil {
|
|
return nil, err
|
|
}
|
|
remPubKey, remSignature := authSigMsg.Key, authSigMsg.Sig
|
|
if !remPubKey.VerifyBytes(challenge[:], remSignature) {
|
|
return nil, errors.New("Challenge verification failed")
|
|
}
|
|
|
|
// We've authorized.
|
|
sc.remPubKey = remPubKey
|
|
return sc, nil
|
|
}
|
|
|
|
// Returns authenticated remote pubkey
|
|
func (sc *SecretConnection) RemotePubKey() crypto.PubKey {
|
|
return sc.remPubKey
|
|
}
|
|
|
|
// Writes encrypted frames of `sealedFrameSize`
|
|
// CONTRACT: data smaller than dataMaxSize is read atomically.
|
|
func (sc *SecretConnection) Write(data []byte) (n int, err error) {
|
|
for 0 < len(data) {
|
|
var frame = make([]byte, totalFrameSize)
|
|
var chunk []byte
|
|
if dataMaxSize < len(data) {
|
|
chunk = data[:dataMaxSize]
|
|
data = data[dataMaxSize:]
|
|
} else {
|
|
chunk = data
|
|
data = nil
|
|
}
|
|
chunkLength := len(chunk)
|
|
binary.BigEndian.PutUint32(frame, uint32(chunkLength))
|
|
copy(frame[dataLenSize:], chunk)
|
|
|
|
// encrypt the frame
|
|
var sealedFrame = make([]byte, sealedFrameSize)
|
|
secretbox.Seal(sealedFrame[:0], frame, sc.sendNonce, sc.shrSecret)
|
|
// fmt.Printf("secretbox.Seal(sealed:%X,sendNonce:%X,shrSecret:%X\n", sealedFrame, sc.sendNonce, sc.shrSecret)
|
|
incr2Nonce(sc.sendNonce)
|
|
// end encryption
|
|
|
|
_, err := sc.conn.Write(sealedFrame)
|
|
if err != nil {
|
|
return n, err
|
|
}
|
|
n += len(chunk)
|
|
}
|
|
return
|
|
}
|
|
|
|
// CONTRACT: data smaller than dataMaxSize is read atomically.
|
|
func (sc *SecretConnection) Read(data []byte) (n int, err error) {
|
|
if 0 < len(sc.recvBuffer) {
|
|
n = copy(data, sc.recvBuffer)
|
|
sc.recvBuffer = sc.recvBuffer[n:]
|
|
return
|
|
}
|
|
|
|
sealedFrame := make([]byte, sealedFrameSize)
|
|
_, err = io.ReadFull(sc.conn, sealedFrame)
|
|
if err != nil {
|
|
return
|
|
}
|
|
|
|
// decrypt the frame
|
|
var frame = make([]byte, totalFrameSize)
|
|
// fmt.Printf("secretbox.Open(sealed:%X,recvNonce:%X,shrSecret:%X\n", sealedFrame, sc.recvNonce, sc.shrSecret)
|
|
_, ok := secretbox.Open(frame[:0], sealedFrame, sc.recvNonce, sc.shrSecret)
|
|
if !ok {
|
|
return n, errors.New("Failed to decrypt SecretConnection")
|
|
}
|
|
incr2Nonce(sc.recvNonce)
|
|
// end decryption
|
|
|
|
var chunkLength = binary.BigEndian.Uint32(frame) // read the first two bytes
|
|
if chunkLength > dataMaxSize {
|
|
return 0, errors.New("chunkLength is greater than dataMaxSize")
|
|
}
|
|
var chunk = frame[dataLenSize : dataLenSize+chunkLength]
|
|
|
|
n = copy(data, chunk)
|
|
sc.recvBuffer = chunk[n:]
|
|
return
|
|
}
|
|
|
|
// Implements net.Conn
|
|
func (sc *SecretConnection) Close() error { return sc.conn.Close() }
|
|
func (sc *SecretConnection) LocalAddr() net.Addr { return sc.conn.(net.Conn).LocalAddr() }
|
|
func (sc *SecretConnection) RemoteAddr() net.Addr { return sc.conn.(net.Conn).RemoteAddr() }
|
|
func (sc *SecretConnection) SetDeadline(t time.Time) error { return sc.conn.(net.Conn).SetDeadline(t) }
|
|
func (sc *SecretConnection) SetReadDeadline(t time.Time) error {
|
|
return sc.conn.(net.Conn).SetReadDeadline(t)
|
|
}
|
|
func (sc *SecretConnection) SetWriteDeadline(t time.Time) error {
|
|
return sc.conn.(net.Conn).SetWriteDeadline(t)
|
|
}
|
|
|
|
func genEphKeys() (ephPub, ephPriv *[32]byte) {
|
|
var err error
|
|
ephPub, ephPriv, err = box.GenerateKey(crand.Reader)
|
|
if err != nil {
|
|
panic("Could not generate ephemeral keypairs")
|
|
}
|
|
return
|
|
}
|
|
|
|
func shareEphPubKey(conn io.ReadWriteCloser, locEphPub *[32]byte) (remEphPub *[32]byte, err error) {
|
|
|
|
// Send our pubkey and receive theirs in tandem.
|
|
var trs, _ = cmn.Parallel(
|
|
func(_ int) (val interface{}, err error, abort bool) {
|
|
var _, err1 = cdc.MarshalBinaryWriter(conn, locEphPub)
|
|
if err1 != nil {
|
|
return nil, err1, true // abort
|
|
} else {
|
|
return nil, nil, false
|
|
}
|
|
},
|
|
func(_ int) (val interface{}, err error, abort bool) {
|
|
var _remEphPub [32]byte
|
|
var _, err2 = cdc.UnmarshalBinaryReader(conn, &_remEphPub, 1024*1024) // TODO
|
|
if err2 != nil {
|
|
return nil, err2, true // abort
|
|
} else {
|
|
return _remEphPub, nil, false
|
|
}
|
|
},
|
|
)
|
|
|
|
// If error:
|
|
if trs.FirstError() != nil {
|
|
err = trs.FirstError()
|
|
return
|
|
}
|
|
|
|
// Otherwise:
|
|
var _remEphPub = trs.FirstValue().([32]byte)
|
|
return &_remEphPub, nil
|
|
}
|
|
|
|
func computeSharedSecret(remPubKey, locPrivKey *[32]byte) (shrSecret *[32]byte) {
|
|
shrSecret = new([32]byte)
|
|
box.Precompute(shrSecret, remPubKey, locPrivKey)
|
|
return
|
|
}
|
|
|
|
func sort32(foo, bar *[32]byte) (lo, hi *[32]byte) {
|
|
if bytes.Compare(foo[:], bar[:]) < 0 {
|
|
lo = foo
|
|
hi = bar
|
|
} else {
|
|
lo = bar
|
|
hi = foo
|
|
}
|
|
return
|
|
}
|
|
|
|
func genNonces(loPubKey, hiPubKey *[32]byte, locIsLo bool) (recvNonce, sendNonce *[24]byte) {
|
|
nonce1 := hash24(append(loPubKey[:], hiPubKey[:]...))
|
|
nonce2 := new([24]byte)
|
|
copy(nonce2[:], nonce1[:])
|
|
nonce2[len(nonce2)-1] ^= 0x01
|
|
if locIsLo {
|
|
recvNonce = nonce1
|
|
sendNonce = nonce2
|
|
} else {
|
|
recvNonce = nonce2
|
|
sendNonce = nonce1
|
|
}
|
|
return
|
|
}
|
|
|
|
func genChallenge(loPubKey, hiPubKey *[32]byte) (challenge *[32]byte) {
|
|
return hash32(append(loPubKey[:], hiPubKey[:]...))
|
|
}
|
|
|
|
func signChallenge(challenge *[32]byte, locPrivKey crypto.PrivKey) (signature crypto.Signature) {
|
|
signature = locPrivKey.Sign(challenge[:])
|
|
return
|
|
}
|
|
|
|
type authSigMessage struct {
|
|
Key crypto.PubKey
|
|
Sig crypto.Signature
|
|
}
|
|
|
|
func shareAuthSignature(sc *SecretConnection, pubKey crypto.PubKey, signature crypto.Signature) (recvMsg authSigMessage, err error) {
|
|
|
|
// Send our info and receive theirs in tandem.
|
|
var trs, _ = cmn.Parallel(
|
|
func(_ int) (val interface{}, err error, abort bool) {
|
|
var _, err1 = cdc.MarshalBinaryWriter(sc, authSigMessage{pubKey, signature})
|
|
if err1 != nil {
|
|
return nil, err1, true // abort
|
|
} else {
|
|
return nil, nil, false
|
|
}
|
|
},
|
|
func(_ int) (val interface{}, err error, abort bool) {
|
|
var _recvMsg authSigMessage
|
|
var _, err2 = cdc.UnmarshalBinaryReader(sc, &_recvMsg, 1024*1024) // TODO
|
|
if err2 != nil {
|
|
return nil, err2, true // abort
|
|
} else {
|
|
return _recvMsg, nil, false
|
|
}
|
|
},
|
|
)
|
|
|
|
// If error:
|
|
if trs.FirstError() != nil {
|
|
err = trs.FirstError()
|
|
return
|
|
}
|
|
|
|
var _recvMsg = trs.FirstValue().(authSigMessage)
|
|
return _recvMsg, nil
|
|
}
|
|
|
|
//--------------------------------------------------------------------------------
|
|
|
|
// sha256
|
|
func hash32(input []byte) (res *[32]byte) {
|
|
hasher := sha256.New()
|
|
hasher.Write(input) // nolint: errcheck, gas
|
|
resSlice := hasher.Sum(nil)
|
|
res = new([32]byte)
|
|
copy(res[:], resSlice)
|
|
return
|
|
}
|
|
|
|
// We only fill in the first 20 bytes with ripemd160
|
|
func hash24(input []byte) (res *[24]byte) {
|
|
hasher := ripemd160.New()
|
|
hasher.Write(input) // nolint: errcheck, gas
|
|
resSlice := hasher.Sum(nil)
|
|
res = new([24]byte)
|
|
copy(res[:], resSlice)
|
|
return
|
|
}
|
|
|
|
// increment nonce big-endian by 2 with wraparound.
|
|
func incr2Nonce(nonce *[24]byte) {
|
|
incrNonce(nonce)
|
|
incrNonce(nonce)
|
|
}
|
|
|
|
// increment nonce big-endian by 1 with wraparound.
|
|
func incrNonce(nonce *[24]byte) {
|
|
for i := 23; 0 <= i; i-- {
|
|
nonce[i]++
|
|
if nonce[i] != 0 {
|
|
return
|
|
}
|
|
}
|
|
}
|