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whisper/whisperv6: remove aesnonce (#15578)

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As per EIP-627, the salt for symmetric encryption is now
part of the payload. This commit does that.
This commit is contained in:
Guillaume Ballet
2017-12-08 11:40:59 +01:00
committed by Felix Lange
parent b5874273ce
commit d95962cd5d
8 changed files with 168 additions and 73 deletions
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46
whisper/whisperv6/message.go
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@@ -61,6 +61,7 @@ type ReceivedMessage struct {
Payload []byte
Padding []byte
Signature []byte
Salt []byte
PoW float64 // Proof of work as described in the Whisper spec
Sent uint32 // Time when the message was posted into the network
@@ -196,31 +197,31 @@ 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) (nonce []byte, err error) {
func (msg *sentMessage) encryptSymmetric(key []byte) (err error) {
if !validateSymmetricKey(key) {
return nil, errors.New("invalid key provided for symmetric encryption")
return errors.New("invalid key provided for symmetric encryption")
}
block, err := aes.NewCipher(key)
if err != nil {
return nil, err
return err
}
aesgcm, err := cipher.NewGCM(block)
if err != nil {
return nil, err
return err
}
// never use more than 2^32 random nonces with a given key
nonce = make([]byte, aesgcm.NonceSize())
_, err = crand.Read(nonce)
salt := make([]byte, aesgcm.NonceSize())
_, err = crand.Read(salt)
if err != nil {
return nil, err
} else if !validateSymmetricKey(nonce) {
return nil, errors.New("crypto/rand failed to generate nonce")
return err
} else if !validateSymmetricKey(salt) {
return errors.New("crypto/rand failed to generate salt")
}
msg.Raw = aesgcm.Seal(nil, nonce, msg.Raw, nil)
return nonce, nil
msg.Raw = append(aesgcm.Seal(nil, salt, msg.Raw, nil), salt...)
return nil
}
// Wrap bundles the message into an Envelope to transmit over the network.
@@ -233,11 +234,10 @@ func (msg *sentMessage) Wrap(options *MessageParams) (envelope *Envelope, err er
return nil, err
}
}
var nonce []byte
if options.Dst != nil {
err = msg.encryptAsymmetric(options.Dst)
} else if options.KeySym != nil {
nonce, err = msg.encryptSymmetric(options.KeySym)
err = msg.encryptSymmetric(options.KeySym)
} else {
err = errors.New("unable to encrypt the message: neither symmetric nor assymmetric key provided")
}
@@ -245,7 +245,7 @@ func (msg *sentMessage) Wrap(options *MessageParams) (envelope *Envelope, err er
return nil, err
}
envelope = NewEnvelope(options.TTL, options.Topic, nonce, msg)
envelope = NewEnvelope(options.TTL, options.Topic, msg)
if err = envelope.Seal(options); err != nil {
return nil, err
}
@@ -254,7 +254,14 @@ 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, nonce []byte) error {
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 {
return errors.New("missing salt or invalid payload in symmetric message")
}
salt := msg.Raw[len(msg.Raw)-AESNonceLength:]
block, err := aes.NewCipher(key)
if err != nil {
return err
@@ -263,15 +270,16 @@ func (msg *ReceivedMessage) decryptSymmetric(key []byte, nonce []byte) error {
if err != nil {
return err
}
if len(nonce) != aesgcm.NonceSize() {
log.Error("decrypting the message", "AES nonce size", len(nonce))
return errors.New("wrong AES nonce size")
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, nonce, msg.Raw, nil)
decrypted, err := aesgcm.Open(nil, salt, msg.Raw[:len(msg.Raw)-AESNonceLength], nil)
if err != nil {
return err
}
msg.Raw = decrypted
msg.Salt = salt
return nil
}