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whisper: message format changed

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This commit is contained in:
Vlad 2018-01-12 19:35:36 +02:00
parent 3f40b22dac
commit 7d58a9bbdd
8 changed files with 152 additions and 175 deletions
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6
whisper/whisperv6/api.go
View file

@ -277,7 +277,7 @@ func (api *PublicWhisperAPI) Post(ctx context.Context, req NewMessage) (bool, er
if params.KeySym, err = api.w.GetSymKey(req.SymKeyID); err != nil {
return false, err
}
if !validateSymmetricKey(params.KeySym) {
if !validateRandomData(params.KeySym, aesKeyLength) {
return false, ErrInvalidSymmetricKey
}
}
@ -383,7 +383,7 @@ func (api *PublicWhisperAPI) Messages(ctx context.Context, crit Criteria) (*rpc.
if err != nil {
return nil, err
}
if !validateSymmetricKey(key) {
if !validateRandomData(key, aesKeyLength) {
return nil, ErrInvalidSymmetricKey
}
filter.KeySym = key
@ -555,7 +555,7 @@ func (api *PublicWhisperAPI) NewMessageFilter(req Criteria) (string, error) {
if keySym, err = api.w.GetSymKey(req.SymKeyID); err != nil {
return "", err
}
if !validateSymmetricKey(keySym) {
if !validateRandomData(keySym, aesKeyLength) {
return "", ErrInvalidSymmetricKey
}
}

6
whisper/whisperv6/doc.go
View file

@ -48,13 +48,13 @@ const (
p2pMessageCode = 127 // peer-to-peer message (to be consumed by the peer, but not forwarded any further)
NumberOfMessageCodes = 128
paddingMask = byte(3)
auxFieldSizeMask = byte(3) // mask used to extract the size of auxiliary field from the flags
signatureFlag = byte(4)
TopicLength = 4 // in bytes
signatureLength = 65 // in bytes
aesKeyLength = 32 // in bytes
AESNonceLength = 12 // in bytes
aesNonceLength = 12 // in bytes; for more info please see cipher.gcmStandardNonceSize & aesgcm.NonceSize()
keyIdSize = 32 // in bytes
bloomFilterSize = 64 // in bytes
@ -64,7 +64,7 @@ const (
DefaultMaxMessageSize = uint32(1024 * 1024)
DefaultMinimumPoW = 0.2
padSizeLimit = 256 // just an arbitrary number, could be changed without breaking the protocol (must not exceed 2^24)
padSizeLimit = 256 // just an arbitrary number, could be changed without breaking the protocol
messageQueueLimit = 1024
expirationCycle = time.Second

5
whisper/whisperv6/envelope.go
View file

@ -198,8 +198,7 @@ func (e *Envelope) OpenSymmetric(key []byte) (msg *ReceivedMessage, err error) {
// Open tries to decrypt an envelope, and populates the message fields in case of success.
func (e *Envelope) Open(watcher *Filter) (msg *ReceivedMessage) {
// The API interface forbids filters doing both symmetric and
// asymmetric encryption.
// The API interface forbids filters doing both symmetric and asymmetric encryption.
if watcher.expectsAsymmetricEncryption() && watcher.expectsSymmetricEncryption() {
return nil
}
@ -217,7 +216,7 @@ func (e *Envelope) Open(watcher *Filter) (msg *ReceivedMessage) {
}
if msg != nil {
ok := msg.Validate()
ok := msg.ValidateAndParse()
if !ok {
return nil
}

197
whisper/whisperv6/message.go
View file

@ -25,6 +25,7 @@ import (
crand "crypto/rand"
"encoding/binary"
"errors"
mrand "math/rand"
"strconv"
"github.com/ethereum/go-ethereum/common"
@ -54,7 +55,7 @@ type sentMessage struct {
}
// ReceivedMessage represents a data packet to be received through the
// Whisper protocol.
// Whisper protocol and successfully decrypted.
type ReceivedMessage struct {
Raw []byte
@ -70,7 +71,7 @@ type ReceivedMessage struct {
Dst *ecdsa.PublicKey // Message recipient (identity used to decode the message)
Topic TopicType
SymKeyHash common.Hash // The Keccak256Hash of the key, associated with the Topic
SymKeyHash common.Hash // The Keccak256Hash of the key
EnvelopeHash common.Hash // Message envelope hash to act as a unique id
}
@ -89,80 +90,58 @@ func (msg *ReceivedMessage) isAsymmetricEncryption() bool {
// NewMessage creates and initializes a non-signed, non-encrypted Whisper message.
func NewSentMessage(params *MessageParams) (*sentMessage, error) {
msg := sentMessage{}
msg.Raw = make([]byte, 1, len(params.Payload)+len(params.Padding)+signatureLength+padSizeLimit)
msg.Raw = make([]byte, 1, 5+len(params.Payload)+len(params.Padding)+signatureLength+padSizeLimit)
msg.Raw[0] = 0 // set all the flags to zero
err := msg.appendPadding(params)
if err != nil {
return nil, err
}
msg.addPayloadSizeField(params.Payload)
msg.Raw = append(msg.Raw, params.Payload...)
return &msg, nil
err := msg.appendPadding(params)
return &msg, err
}
// getSizeOfLength returns the number of bytes necessary to encode the entire size padding (including these bytes)
func getSizeOfLength(b []byte) (sz int, err error) {
sz = intSize(len(b)) // first iteration
sz = intSize(len(b) + sz) // second iteration
if sz > 3 {
err = errors.New("oversized padding parameter")
}
return sz, err
// appendPayloadSizeField appends the auxiliary field containing the size of payload
func (msg *sentMessage) addPayloadSizeField(payload []byte) {
fieldSize := getAuxFieldSize(payload)
field := make([]byte, 4)
binary.LittleEndian.PutUint32(field, uint32(len(payload)))
field = field[:fieldSize]
msg.Raw = append(msg.Raw, field...)
msg.Raw[0] |= byte(fieldSize)
}
// sizeOfIntSize returns minimal number of bytes necessary to encode an integer value
func intSize(i int) (s int) {
for s = 1; i >= 256; s++ {
i /= 256
// getAuxFieldSize returns the number of bytes necessary to encode the size of payload
func getAuxFieldSize(payload []byte) int {
s := 1
for i := len(payload); i >= 256; i /= 256 {
s++
}
return s
}
// appendPadding appends the pseudorandom padding bytes and sets the padding flag.
// The last byte contains the size of padding (thus, its size must not exceed 256).
// appendPadding appends the padding specified in params.
// If no padding is provided in params, then random padding is generated.
func (msg *sentMessage) appendPadding(params *MessageParams) error {
rawSize := len(params.Payload) + 1
if len(params.Padding) != 0 {
// padding data was provided by the Dapp, just use it as is
msg.Raw = append(msg.Raw, params.Padding...)
return nil
}
auxFieldSize := getAuxFieldSize(params.Payload)
rawSize := 1 + auxFieldSize + len(params.Payload)
if params.Src != nil {
rawSize += signatureLength
}
if params.KeySym != nil {
rawSize += AESNonceLength
}
odd := rawSize % padSizeLimit
if len(params.Padding) != 0 {
padSize := len(params.Padding)
padLengthSize, err := getSizeOfLength(params.Padding)
paddingSize := padSizeLimit - odd
pad := make([]byte, paddingSize)
_, err := crand.Read(pad)
if err != nil {
return err
}
totalPadSize := padSize + padLengthSize
buf := make([]byte, 8)
binary.LittleEndian.PutUint32(buf, uint32(totalPadSize))
buf = buf[:padLengthSize]
msg.Raw = append(msg.Raw, buf...)
msg.Raw = append(msg.Raw, params.Padding...)
msg.Raw[0] |= byte(padLengthSize) // number of bytes indicating the padding size
} else if odd != 0 {
totalPadSize := padSizeLimit - odd
if totalPadSize > 255 {
// this algorithm is only valid if padSizeLimit < 256.
// if padSizeLimit will ever change, please fix the algorithm
// (please see also ReceivedMessage.extractPadding() function).
panic("please fix the padding algorithm before releasing new version")
}
buf := make([]byte, totalPadSize)
_, err := crand.Read(buf[1:])
if err != nil {
return err
}
if totalPadSize > 6 && !validateSymmetricKey(buf) {
return errors.New("failed to generate random padding of size " + strconv.Itoa(totalPadSize))
}
buf[0] = byte(totalPadSize)
msg.Raw = append(msg.Raw, buf...)
msg.Raw[0] |= byte(0x1) // number of bytes indicating the padding size
if !validateRandomData(pad, paddingSize) {
return errors.New("failed to generate random padding of size " + strconv.Itoa(paddingSize))
}
msg.Raw = append(msg.Raw, pad...)
return nil
}
@ -175,11 +154,11 @@ func (msg *sentMessage) sign(key *ecdsa.PrivateKey) error {
return nil
}
msg.Raw[0] |= signatureFlag
msg.Raw[0] |= signatureFlag // it is important to set this flag before signing
hash := crypto.Keccak256(msg.Raw)
signature, err := crypto.Sign(hash, key)
if err != nil {
msg.Raw[0] &= ^signatureFlag // clear the flag
msg.Raw[0] &= (0xFF ^ signatureFlag) // clear the flag
return err
}
msg.Raw = append(msg.Raw, signature...)
@ -201,10 +180,9 @@ func (msg *sentMessage) encryptAsymmetric(key *ecdsa.PublicKey) error {
// encryptSymmetric encrypts a message with a topic key, using AES-GCM-256.
// nonce size should be 12 bytes (see cipher.gcmStandardNonceSize).
func (msg *sentMessage) encryptSymmetric(key []byte) (err error) {
if !validateSymmetricKey(key) {
return errors.New("invalid key provided for symmetric encryption")
if !validateRandomData(key, aesKeyLength) {
return errors.New("invalid key provided for symmetric encryption, size: " + strconv.Itoa(len(key)))
}
block, err := aes.NewCipher(key)
if err != nil {
return err
@ -213,18 +191,44 @@ func (msg *sentMessage) encryptSymmetric(key []byte) (err error) {
if err != nil {
return err
}
// never use more than 2^32 random nonces with a given key
salt := make([]byte, aesgcm.NonceSize())
_, err = crand.Read(salt)
salt, err := generateSecureRandomData(aesNonceLength) // never use more than 2^32 random nonces with a given key
if err != nil {
return err
} else if !validateSymmetricKey(salt) {
return errors.New("crypto/rand failed to generate salt")
}
encrypted := aesgcm.Seal(nil, salt, msg.Raw, nil)
msg.Raw = append(encrypted, salt...)
return nil
}
msg.Raw = append(aesgcm.Seal(nil, salt, msg.Raw, nil), salt...)
return nil
// generateSecureRandomData generates random data where extra security is required.
// The purpose of this function is to prevent some bugs in software or in hardware
// from delivering not-very-random data. This is especially useful for AES nonce,
// where true randomness does not really matter, but it is very important to have
// a unique nonce for every message.
func generateSecureRandomData(length int) ([]byte, error) {
x := make([]byte, length)
y := make([]byte, length)
res := make([]byte, length)
_, err := crand.Read(x)
if err != nil {
return nil, err
} else if !validateRandomData(x, length) {
return nil, errors.New("crypto/rand failed to generate secure random data")
}
_, err = mrand.Read(y)
if err != nil {
return nil, err
} else if !validateRandomData(y, length) {
return nil, errors.New("math/rand failed to generate secure random data")
}
for i := 0; i < length; i++ {
res[i] = x[i] ^ y[i]
}
if !validateRandomData(res, length) {
return nil, errors.New("failed to generate secure random data")
}
return res, nil
}
// Wrap bundles the message into an Envelope to transmit over the network.
@ -258,12 +262,11 @@ func (msg *sentMessage) Wrap(options *MessageParams) (envelope *Envelope, err er
// decryptSymmetric decrypts a message with a topic key, using AES-GCM-256.
// nonce size should be 12 bytes (see cipher.gcmStandardNonceSize).
func (msg *ReceivedMessage) decryptSymmetric(key []byte) error {
// In v6, symmetric messages are expected to contain the 12-byte
// "salt" at the end of the payload.
if len(msg.Raw) < AESNonceLength {
// symmetric messages are expected to contain the 12-byte nonce at the end of the payload
if len(msg.Raw) < aesNonceLength {
return errors.New("missing salt or invalid payload in symmetric message")
}
salt := msg.Raw[len(msg.Raw)-AESNonceLength:]
salt := msg.Raw[len(msg.Raw)-aesNonceLength:]
block, err := aes.NewCipher(key)
if err != nil {
@ -273,11 +276,7 @@ func (msg *ReceivedMessage) decryptSymmetric(key []byte) error {
if err != nil {
return err
}
if len(salt) != aesgcm.NonceSize() {
log.Error("decrypting the message", "AES salt size", len(salt))
return errors.New("wrong AES salt size")
}
decrypted, err := aesgcm.Open(nil, salt, msg.Raw[:len(msg.Raw)-AESNonceLength], nil)
decrypted, err := aesgcm.Open(nil, salt, msg.Raw[:len(msg.Raw)-aesNonceLength], nil)
if err != nil {
return err
}
@ -295,8 +294,8 @@ func (msg *ReceivedMessage) decryptAsymmetric(key *ecdsa.PrivateKey) error {
return err
}
// Validate checks the validity and extracts the fields in case of success
func (msg *ReceivedMessage) Validate() bool {
// Validate checks the message validity and extracts the fields in case of success.
func (msg *ReceivedMessage) ValidateAndParse() bool {
end := len(msg.Raw)
if end < 1 {
return false
@ -307,40 +306,30 @@ func (msg *ReceivedMessage) Validate() bool {
if end <= 1 {
return false
}
msg.Signature = msg.Raw[end:]
msg.Signature = msg.Raw[end : end+signatureLength]
msg.Src = msg.SigToPubKey()
if msg.Src == nil {
return false
}
}
padSize, ok := msg.extractPadding(end)
if !ok {
beg := 1
payloadSize := 0
auxFieldSize := int(msg.Raw[0] & auxFieldSizeMask) // number of bytes indicating the size of payload
if auxFieldSize != 0 {
payloadSize = int(bytesToUintLittleEndian(msg.Raw[beg : beg+auxFieldSize]))
if payloadSize+1 > end {
return false
}
beg += auxFieldSize
msg.Payload = msg.Raw[beg : beg+payloadSize]
}
msg.Payload = msg.Raw[1+padSize : end]
beg += payloadSize
msg.Padding = msg.Raw[beg:end]
return true
}
// extractPadding extracts the padding from raw message.
// although we don't support sending messages with padding size
// exceeding 255 bytes, such messages are perfectly valid, and
// can be successfully decrypted.
func (msg *ReceivedMessage) extractPadding(end int) (int, bool) {
paddingSize := 0
sz := int(msg.Raw[0] & paddingMask) // number of bytes indicating the entire size of padding (including these bytes)
// could be zero -- it means no padding
if sz != 0 {
paddingSize = int(bytesToUintLittleEndian(msg.Raw[1 : 1+sz]))
if paddingSize < sz || paddingSize+1 > end {
return 0, false
}
msg.Padding = msg.Raw[1+sz : 1+paddingSize]
}
return paddingSize, true
}
// Recover retrieves the public key of the message signer.
func (msg *ReceivedMessage) SigToPubKey() *ecdsa.PublicKey {
defer func() { recover() }() // in case of invalid signature
@ -353,7 +342,7 @@ func (msg *ReceivedMessage) SigToPubKey() *ecdsa.PublicKey {
return pub
}
// hash calculates the SHA3 checksum of the message flags, payload and padding.
// hash calculates the SHA3 checksum of the message flags, auxiliary field, payload and padding.
func (msg *ReceivedMessage) hash() []byte {
if isMessageSigned(msg.Raw[0]) {
sz := len(msg.Raw) - signatureLength

56
whisper/whisperv6/message_test.go
View file

@ -18,9 +18,12 @@ package whisperv6
import (
"bytes"
"crypto/aes"
"crypto/cipher"
mrand "math/rand"
"testing"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/rlp"
)
@ -90,8 +93,8 @@ func singleMessageTest(t *testing.T, symmetric bool) {
t.Fatalf("failed to encrypt with seed %d: %s.", seed, err)
}
if !decrypted.Validate() {
t.Fatalf("failed to validate with seed %d.", seed)
if !decrypted.ValidateAndParse() {
t.Fatalf("failed to validate with seed %d, symmetric = %v.", seed, symmetric)
}
if !bytes.Equal(text, decrypted.Payload) {
@ -206,7 +209,7 @@ func TestEnvelopeOpen(t *testing.T) {
InitSingleTest()
var symmetric bool
for i := 0; i < 256; i++ {
for i := 0; i < 32; i++ {
singleEnvelopeOpenTest(t, symmetric)
symmetric = !symmetric
}
@ -417,30 +420,6 @@ func TestPadding(t *testing.T) {
}
}
func TestPaddingAppendedToSymMessages(t *testing.T) {
params := &MessageParams{
Payload: make([]byte, 246),
KeySym: make([]byte, aesKeyLength),
}
// Simulate a message with a payload just under 256 so that
// payload + flag + aesnonce > 256. Check that the result
// is padded on the next 256 boundary.
msg := sentMessage{}
msg.Raw = make([]byte, len(params.Payload)+1+AESNonceLength)
err := msg.appendPadding(params)
if err != nil {
t.Fatalf("Error appending padding to message %v", err)
return
}
if len(msg.Raw) != 512 {
t.Errorf("Invalid size %d != 512", len(msg.Raw))
}
}
func TestPaddingAppendedToSymMessagesWithSignature(t *testing.T) {
params := &MessageParams{
Payload: make([]byte, 246),
@ -456,10 +435,10 @@ func TestPaddingAppendedToSymMessagesWithSignature(t *testing.T) {
params.Src = pSrc
// Simulate a message with a payload just under 256 so that
// payload + flag + aesnonce > 256. Check that the result
// payload + flag + signature > 256. Check that the result
// is padded on the next 256 boundary.
msg := sentMessage{}
msg.Raw = make([]byte, len(params.Payload)+1+AESNonceLength+signatureLength)
msg.Raw = make([]byte, 1+1+len(params.Payload))
err = msg.appendPadding(params)
@ -468,7 +447,24 @@ func TestPaddingAppendedToSymMessagesWithSignature(t *testing.T) {
return
}
if len(msg.Raw) != 512 {
if len(msg.Raw) != 512-signatureLength {
t.Errorf("Invalid size %d != 512", len(msg.Raw))
}
}
func TestAesNonce(t *testing.T) {
key := hexutil.MustDecode("0x03ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd31")
block, err := aes.NewCipher(key)
if err != nil {
t.Fatalf("NewCipher failed: %s", err)
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
t.Fatalf("NewGCM failed: %s", err)
}
// This is the most important single test in this package.
// If it fails, whisper will not be working.
if aesgcm.NonceSize() != aesNonceLength {
t.Fatalf("Nonce size is wrong. This is a critical error. Apparently AES nonce size have changed in the new version of AES GCM package. Whisper will not be working until this problem is resolved.")
}
}

3
whisper/whisperv6/peer_test.go
View file

@ -27,6 +27,7 @@ import (
"time"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/common/hexutil"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/p2p"
"github.com/ethereum/go-ethereum/p2p/discover"
@ -85,7 +86,7 @@ type TestNode struct {
var result TestData
var nodes [NumNodes]*TestNode
var sharedKey []byte = []byte("some arbitrary data here")
var sharedKey []byte = hexutil.MustDecode("0x03ca634cae0d49acb401d8a4c6b6fe8c55b70d115bf400769cc1400f3258cd31")
var sharedTopic TopicType = TopicType{0xF, 0x1, 0x2, 0}
var expectedMessage []byte = []byte("per rectum ad astra")
var masterBloomFilter []byte

24
whisper/whisperv6/whisper.go
View file

@ -19,7 +19,6 @@ package whisperv6
import (
"bytes"
"crypto/ecdsa"
crand "crypto/rand"
"crypto/sha256"
"fmt"
"math"
@ -442,11 +441,10 @@ func (w *Whisper) GetPrivateKey(id string) (*ecdsa.PrivateKey, error) {
// GenerateSymKey generates a random symmetric key and stores it under id,
// which is then returned. Will be used in the future for session key exchange.
func (w *Whisper) GenerateSymKey() (string, error) {
key := make([]byte, aesKeyLength)
_, err := crand.Read(key)
key, err := generateSecureRandomData(aesKeyLength)
if err != nil {
return "", err
} else if !validateSymmetricKey(key) {
} else if !validateRandomData(key, aesKeyLength) {
return "", fmt.Errorf("error in GenerateSymKey: crypto/rand failed to generate random data")
}
@ -983,9 +981,16 @@ func validatePrivateKey(k *ecdsa.PrivateKey) bool {
return ValidatePublicKey(&k.PublicKey)
}
// validateSymmetricKey returns false if the key contains all zeros
func validateSymmetricKey(k []byte) bool {
return len(k) > 0 && !containsOnlyZeros(k)
// validateSymmetricKey returns false if the key contains all zeros,
// which is a simplest and the most common bug.
func validateRandomData(k []byte, expectedSize int) bool {
if len(k) != expectedSize {
return false
}
if expectedSize > 4 && containsOnlyZeros(k) {
return false
}
return true
}
// containsOnlyZeros checks if the data contain only zeros.
@ -1019,12 +1024,11 @@ func BytesToUintBigEndian(b []byte) (res uint64) {
// GenerateRandomID generates a random string, which is then returned to be used as a key id
func GenerateRandomID() (id string, err error) {
buf := make([]byte, keyIdSize)
_, err = crand.Read(buf)
buf, err := generateSecureRandomData(keyIdSize)
if err != nil {
return "", err
}
if !validateSymmetricKey(buf) {
if !validateRandomData(buf, keyIdSize) {
return "", fmt.Errorf("error in generateRandomID: crypto/rand failed to generate random data")
}
id = common.Bytes2Hex(buf)

18
whisper/whisperv6/whisper_test.go
View file

@ -81,7 +81,7 @@ func TestWhisperBasic(t *testing.T) {
}
derived := pbkdf2.Key([]byte(peerID), nil, 65356, aesKeyLength, sha256.New)
if !validateSymmetricKey(derived) {
if !validateRandomData(derived, aesKeyLength) {
t.Fatalf("failed validateSymmetricKey with param = %v.", derived)
}
if containsOnlyZeros(derived) {
@ -448,24 +448,12 @@ func TestWhisperSymKeyManagement(t *testing.T) {
if !w.HasSymKey(id2) {
t.Fatalf("HasSymKey(id2) failed.")
}
if k1 == nil {
t.Fatalf("k1 does not exist.")
}
if k2 == nil {
t.Fatalf("k2 does not exist.")
if !validateRandomData(k2, aesKeyLength) {
t.Fatalf("key validation failed.")
}
if !bytes.Equal(k1, k2) {
t.Fatalf("k1 != k2.")
}
if len(k1) != aesKeyLength {
t.Fatalf("wrong length of k1.")
}
if len(k2) != aesKeyLength {
t.Fatalf("wrong length of k2.")
}
if !validateSymmetricKey(k2) {
t.Fatalf("key validation failed.")
}
}
func TestExpiry(t *testing.T) {