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whisper: message format refactoring, initial commit

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Vlad 2018-01-09 00:03:59 +02:00 committed by Guillaume Ballet
parent bb7b29c362
commit cd73f59844
4 changed files with 152 additions and 92 deletions
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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; also returned by 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

@ -204,20 +204,23 @@ func (e *Envelope) Open(watcher *Filter) (msg *ReceivedMessage) {
return nil
}
var symmetric bool
if watcher.expectsAsymmetricEncryption() {
msg, _ = e.OpenAsymmetric(watcher.KeyAsym)
if msg != nil {
symmetric = false
msg.Dst = &watcher.KeyAsym.PublicKey
}
} else if watcher.expectsSymmetricEncryption() {
msg, _ = e.OpenSymmetric(watcher.KeySym)
if msg != nil {
symmetric = true
msg.SymKeyHash = crypto.Keccak256Hash(watcher.KeySym)
}
}
if msg != nil {
ok := msg.Validate()
ok := msg.ValidateAndParse(symmetric)
if !ok {
return nil
}

221
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"
@ -89,80 +90,95 @@ 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, fieldSize)
binary.LittleEndian.PutUint32(field, uint32(len(payload)))
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
// getSizeOfLength returns the number of bytes necessary to encode the size of padding
//func getAuxFieldSize(payload []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
//}
// 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)
//if len(params.Padding) != 0 {
// // padding data was provided by the Dapp, just use it as is
// padSize := len(params.Padding)
// padLengthSize, err := intSize(len(params.Padding))
// 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 {
paddingSize := 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")
//}
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 !validateSymmetricKey(pad) {
return errors.New("failed to generate random padding of size " + strconv.Itoa(paddingSize))
}
//buf[0] = byte(totalPadSize)
msg.Raw = append(msg.Raw, pad...)
//msg.Raw[0] |= byte(0x1) // number of bytes indicating the padding size
//}
return nil
}
@ -175,14 +191,15 @@ 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] ^= signatureFlag // clear the flag
return err
}
msg.Raw = append(msg.Raw, signature...)
return nil
}
@ -204,7 +221,6 @@ func (msg *sentMessage) encryptSymmetric(key []byte) (err error) {
if !validateSymmetricKey(key) {
return errors.New("invalid key provided for symmetric encryption")
}
block, err := aes.NewCipher(key)
if err != nil {
return err
@ -213,18 +229,41 @@ 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 := generateSalt(aesgcm)
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
func generateSalt(aesgcm cipher.AEAD) ([]byte, error) {
// never use more than 2^32 random nonces with a given key
sz := aesgcm.NonceSize()
x1 := make([]byte, sz)
x2 := make([]byte, sz)
salt := make([]byte, sz)
_, err := crand.Read(x1)
if err != nil {
return nil, err
} else if !validateSymmetricKey(x1) {
return nil, errors.New("crypto/rand failed to generate salt")
}
_, err = mrand.Read(x2)
if err != nil {
return nil, err
} else if !validateSymmetricKey(x2) {
return nil, errors.New("math/rand failed to generate salt")
}
for i := 0; i < sz; i++ {
salt[i] = x1[i] ^ x2[i]
}
if !validateSymmetricKey(salt) {
return nil, errors.New("failed to generate salt")
}
return salt, nil
}
// Wrap bundles the message into an Envelope to transmit over the network.
@ -295,31 +334,50 @@ 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(symmetric bool) bool {
end := len(msg.Raw)
if end < 1 {
return false
}
if symmetric {
end -= AESNonceLength
}
if isMessageSigned(msg.Raw[0]) {
end -= signatureLength
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]
}
beg += payloadSize
msg.Padding = msg.Raw[beg:end]
//padSize, ok := msg.extractPadding(end)
//if !ok {
// return false
//}
//msg.Payload = msg.Raw[1+padSize : end]
msg.Payload = msg.Raw[1+padSize : end]
return true
}
@ -327,19 +385,18 @@ func (msg *ReceivedMessage) Validate() bool {
// 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
}
//func (msg *ReceivedMessage) extractPadding(end int) (int, bool) {
// payloadSize := 0
// auxFieldSize := int(msg.Raw[0] & auxFieldSizeMask) // number of bytes indicating the size of payload
// 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 {
@ -353,7 +410,7 @@ 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

2
whisper/whisperv6/message_test.go
View file

@ -90,7 +90,7 @@ func singleMessageTest(t *testing.T, symmetric bool) {
t.Fatalf("failed to encrypt with seed %d: %s.", seed, err)
}
if !decrypted.Validate() {
if !decrypted.ValidateAndParse(symmetric) {
t.Fatalf("failed to validate with seed %d.", seed)
}