mirror of https://github.com/status-im/go-waku.git
wakuv1 envelope format
This commit is contained in:
Richard Ramos
parent
65fc98f450
commit
100a26f49c
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@ -5,11 +5,14 @@ import (
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"crypto/cipher"
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"crypto/ecdsa"
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crand "crypto/rand"
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"encoding/binary"
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"fmt"
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mrand "math/rand"
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"errors"
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"strconv"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/ecies"
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"github.com/status-im/go-waku/waku/v2/protocol"
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)
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@ -22,16 +25,122 @@ const (
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None KeyKind = "None"
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)
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type KeyInfo struct {
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Kind KeyKind
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SymKey []byte
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PrivKey ecdsa.PrivateKey
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// The message to encode
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type Payload struct {
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Data []byte // Raw message payload
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Padding []byte // Used to align data size, since data size alone might reveal important metainformation.
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Key *KeyInfo // Contains the type of encryption to apply and the private key to use for signing the message
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}
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// NOTICE: Extracted from status-go
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// The decoded payload of a received message.
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type DecodedPayload struct {
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Data []byte // Decoded message payload
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Padding []byte // Used to align data size, since data size alone might reveal important metainformation.
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PubKey *ecdsa.PublicKey // The public key that signed the payload
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Signature []byte
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}
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type KeyInfo struct {
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Kind KeyKind // Indicates the type of encryption to use
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SymKey []byte // If the encryption is Symmetric, a Symmetric key must be specified
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PubKey ecdsa.PublicKey // If the encryption is Asymmetric, the public key of the message receptor must be specified
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PrivKey *ecdsa.PrivateKey // Set a privkey if the message requires a signature
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}
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func (payload Payload) Encode(version uint32) ([]byte, error) {
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switch version {
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case 0:
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return payload.Data, nil
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case 1:
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data, err := payload.v1Data()
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if err != nil {
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return nil, err
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}
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if payload.Key.PrivKey != nil {
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data, err = sign(data, *payload.Key.PrivKey)
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if err != nil {
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return nil, err
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}
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}
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switch payload.Key.Kind {
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case Symmetric:
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encoded, err := encryptSymmetric(data, payload.Key.SymKey)
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if err != nil {
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return nil, errors.New("Couldn't encrypt using symmetric key")
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} else {
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return encoded, nil
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}
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case Asymmetric:
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encoded, err := encryptAsymmetric(data, &payload.Key.PubKey)
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if err != nil {
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return nil, errors.New("Couldn't encrypt using asymmetric key")
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} else {
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return encoded, nil
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}
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case None:
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return nil, errors.New("Non supported KeyKind")
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}
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}
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return nil, errors.New("Unsupported WakuMessage version")
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}
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func DecodePayload(message *protocol.WakuMessage, keyInfo *KeyInfo) (*DecodedPayload, error) {
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switch *message.Version {
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case uint32(0):
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return &DecodedPayload{Data: message.Payload}, nil
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case uint32(1):
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switch keyInfo.Kind {
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case Symmetric:
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if keyInfo.SymKey == nil {
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return nil, errors.New("Symmetric key is required")
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}
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fmt.Println("AAA")
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decodedData, err := decryptSymmetric(message.Payload, keyInfo.SymKey)
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if err != nil {
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return nil, errors.New("Couldn't decrypt using symmetric key")
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}
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decodedPayload, err := validateAndParse(decodedData)
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if err != nil {
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return nil, err
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}
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fmt.Println("AAA")
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return decodedPayload, nil
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case Asymmetric:
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if keyInfo.PrivKey == nil {
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return nil, errors.New("Private key is required")
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}
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decodedData, err := decryptAsymmetric(message.Payload, keyInfo.PrivKey)
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if err != nil {
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return nil, errors.New("Couldn't decrypt using asymmetric key")
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}
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decodedPayload, err := validateAndParse(decodedData)
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if err != nil {
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return nil, err
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}
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return decodedPayload, nil
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case None:
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return nil, errors.New("Non supported KeyKind")
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}
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}
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return nil, errors.New("Unsupported WakuMessage version")
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}
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const aesNonceLength = 12
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const aesKeyLength = 32
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const signatureFlag = byte(4)
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const flagsLength = 1
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const padSizeLimit = 256 // just an arbitrary number, could be changed without breaking the protocol
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const signatureLength = 65
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const sizeMask = byte(3)
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// Decrypts a message with a topic key, using AES-GCM-256.
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// nonce size should be 12 bytes (see cipher.gcmStandardNonceSize).
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@ -62,49 +171,23 @@ func decryptSymmetric(payload []byte, key []byte) ([]byte, error) {
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// Decrypts an encrypted payload with a private key.
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func decryptAsymmetric(payload []byte, key *ecdsa.PrivateKey) ([]byte, error) {
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decrypted, err := ecies.ImportECDSA(key).Decrypt(payload, nil, nil)
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if err == nil {
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if err != nil {
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return nil, err
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}
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return decrypted, err
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}
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func DecodePayload(message *protocol.WakuMessage, keyInfo *KeyInfo) ([]byte, error) {
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switch *message.Version {
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case uint32(0):
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return message.Payload, nil
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case uint32(1):
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switch keyInfo.Kind {
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case Symmetric:
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decoded, err := decryptSymmetric(message.Payload, keyInfo.SymKey)
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if err != nil {
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return nil, errors.New("Couldn't decrypt using symmetric key")
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} else {
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return decoded, nil
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}
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case Asymmetric:
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decoded, err := decryptAsymmetric(message.Payload, &keyInfo.PrivKey)
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if err != nil {
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return nil, errors.New("Couldn't decrypt using asymmetric key")
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} else {
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return decoded, nil
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}
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case None:
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return nil, errors.New("Non supported KeyKind")
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}
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}
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return nil, errors.New("Unsupported WakuMessage version")
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}
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// ValidatePublicKey checks the format of the given public key.
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func ValidatePublicKey(k *ecdsa.PublicKey) bool {
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func validatePublicKey(k *ecdsa.PublicKey) bool {
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return k != nil && k.X != nil && k.Y != nil && k.X.Sign() != 0 && k.Y.Sign() != 0
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}
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// Encrypts and returns with a public key.
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func encryptAsymmetric(rawPayload []byte, key *ecdsa.PublicKey) ([]byte, error) {
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if !ValidatePublicKey(key) {
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if !validatePublicKey(key) {
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return nil, errors.New("invalid public key provided for asymmetric encryption")
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}
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encrypted, err := ecies.Encrypt(crand.Reader, ecies.ImportECDSAPublic(key), rawPayload, nil, nil)
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if err == nil {
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return encrypted, nil
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@ -187,29 +270,154 @@ func generateSecureRandomData(length int) ([]byte, error) {
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return res, nil
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}
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func Encode(rawPayload []byte, keyInfo *KeyInfo, version uint32) ([]byte, error) {
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switch version {
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case 0:
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return rawPayload, nil
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case 1:
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switch keyInfo.Kind {
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case Symmetric:
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encoded, err := encryptSymmetric(rawPayload, keyInfo.SymKey)
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if err != nil {
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return nil, errors.New("Couldn't encrypt using symmetric key")
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} else {
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return encoded, nil
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}
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case Asymmetric:
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encoded, err := encryptAsymmetric(rawPayload, &keyInfo.PrivKey.PublicKey)
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if err != nil {
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return nil, errors.New("Couldn't encrypt using asymmetric key")
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} else {
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return encoded, nil
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}
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case None:
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return nil, errors.New("Non supported KeyKind")
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}
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}
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return nil, errors.New("Unsupported WakuMessage version")
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func isMessageSigned(flags byte) bool {
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return (flags & signatureFlag) != 0
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}
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// sign calculates the cryptographic signature for the message,
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// also setting the sign flag.
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func sign(data []byte, privKey ecdsa.PrivateKey) ([]byte, error) {
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result := make([]byte, len(data))
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copy(result, data)
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if isMessageSigned(result[0]) {
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// this should not happen, but no reason to panic
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return result, nil
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}
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result[0] |= signatureFlag // it is important to set this flag before signing
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hash := crypto.Keccak256(result)
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signature, err := crypto.Sign(hash, &privKey)
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if err != nil {
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result[0] &= (0xFF ^ signatureFlag) // clear the flag
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return nil, err
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}
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result = append(result, signature...)
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return result, nil
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}
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func (payload Payload) v1Data() ([]byte, error) {
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const payloadSizeFieldMaxSize = 4
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result := make([]byte, 1, flagsLength+payloadSizeFieldMaxSize+len(payload.Data)+len(payload.Padding)+signatureLength+padSizeLimit)
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result[0] = 0 // set all the flags to zero
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result = payload.addPayloadSizeField(result)
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result = append(result, payload.Data...)
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result, err := payload.appendPadding(result)
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return result, err
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}
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// addPayloadSizeField appends the auxiliary field containing the size of payload
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func (payload Payload) addPayloadSizeField(input []byte) []byte {
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fieldSize := getSizeOfPayloadSizeField(payload.Data)
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field := make([]byte, 4)
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binary.LittleEndian.PutUint32(field, uint32(len(payload.Data)))
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field = field[:fieldSize]
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result := append(input, field...)
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result[0] |= byte(fieldSize)
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return result
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}
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// getSizeOfPayloadSizeField returns the number of bytes necessary to encode the size of payload
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func getSizeOfPayloadSizeField(payload []byte) int {
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s := 1
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for i := len(payload); i >= 256; i /= 256 {
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s++
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}
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return s
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}
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// appendPadding appends the padding specified in params.
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// If no padding is provided in params, then random padding is generated.
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func (payload Payload) appendPadding(input []byte) ([]byte, error) {
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if len(payload.Padding) != 0 {
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// padding data was provided by the Dapp, just use it as is
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result := append(input, payload.Padding...)
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return result, nil
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}
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rawSize := flagsLength + getSizeOfPayloadSizeField(payload.Data) + len(payload.Data)
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if payload.Key.PrivKey != nil {
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rawSize += signatureLength
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}
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odd := rawSize % padSizeLimit
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paddingSize := padSizeLimit - odd
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pad := make([]byte, paddingSize)
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_, err := crand.Read(pad)
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if err != nil {
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return nil, err
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}
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if !validateDataIntegrity(pad, paddingSize) {
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return nil, errors.New("failed to generate random padding of size " + strconv.Itoa(paddingSize))
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}
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result := append(input, pad...)
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return result, nil
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}
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func validateAndParse(input []byte) (*DecodedPayload, error) {
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end := len(input)
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if end < 1 {
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return nil, errors.New("invalid message length")
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}
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msg := new(DecodedPayload)
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if isMessageSigned(input[0]) {
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end -= signatureLength
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if end <= 1 {
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return nil, errors.New("invalid message length")
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}
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msg.Signature = input[end : end+signatureLength]
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var err error
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msg.PubKey, err = msg.sigToPubKey(input)
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if err != nil {
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return nil, err
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}
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}
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beg := 1
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payloadSize := 0
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sizeOfPayloadSizeField := int(input[0] & sizeMask) // number of bytes indicating the size of payload
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if sizeOfPayloadSizeField != 0 {
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if end < beg+sizeOfPayloadSizeField {
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return nil, errors.New("invalid message length")
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}
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payloadSize = int(bytesToUintLittleEndian(input[beg : beg+sizeOfPayloadSizeField]))
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beg += sizeOfPayloadSizeField
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if beg+payloadSize > end {
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return nil, errors.New("invalid message length")
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}
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msg.Data = input[beg : beg+payloadSize]
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}
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beg += payloadSize
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msg.Padding = input[beg:end]
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return msg, nil
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}
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// SigToPubKey returns the public key associated to the message's
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// signature.
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func (p *DecodedPayload) sigToPubKey(input []byte) (*ecdsa.PublicKey, error) {
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defer func() { _ = recover() }() // in case of invalid signature
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hash := crypto.Keccak256(input[0 : len(input)-signatureLength])
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pub, err := crypto.SigToPub(hash, p.Signature)
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if err != nil {
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return nil, err
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}
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return pub, nil
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}
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// bytesToUintLittleEndian converts the slice to 64-bit unsigned integer.
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func bytesToUintLittleEndian(b []byte) (res uint64) {
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mul := uint64(1)
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for i := 0; i < len(b); i++ {
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res += uint64(b[i]) * mul
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mul *= 256
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}
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return res
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}
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