package encryption import ( "crypto/ecdsa" "database/sql" "encoding/hex" "errors" "sync" "time" ecrypto "github.com/ethereum/go-ethereum/crypto" "github.com/ethereum/go-ethereum/crypto/ecies" dr "github.com/status-im/doubleratchet" "go.uber.org/zap" "github.com/status-im/status-protocol-go/crypto" "github.com/status-im/status-protocol-go/encryption/multidevice" ) var ( errSessionNotFound = errors.New("session not found") ErrDeviceNotFound = errors.New("device not found") // ErrNotPairedDevice means that we received a message signed with our public key // but from a device that has not been paired. // This should not happen because the protocol forbids sending a message to // non-paired devices, however, in theory it is possible to receive such a message. ErrNotPairedDevice = errors.New("received a message from not paired device") ) // If we have no bundles, we use a constant so that the message can reach any device. const noInstallationID = "none" type confirmationData struct { header *dr.MessageHeader drInfo *RatchetInfo } // encryptor defines a service that is responsible for the encryption aspect of the protocol. type encryptor struct { persistence *sqlitePersistence config encryptorConfig messageIDs map[string]*confirmationData mutex sync.Mutex logger *zap.Logger } type encryptorConfig struct { InstallationID string // Max number of installations we keep synchronized. MaxInstallations int // How many consecutive messages can be skipped in the receiving chain. MaxSkip int // Any message with seqNo <= currentSeq - maxKeep will be deleted. MaxKeep int // How many keys do we store in total per session. MaxMessageKeysPerSession int // How long before we refresh the interval in milliseconds BundleRefreshInterval int64 // The logging object Logger *zap.Logger } // defaultEncryptorConfig returns the default values used by the encryption service func defaultEncryptorConfig(installationID string, logger *zap.Logger) encryptorConfig { if logger == nil { logger = zap.NewNop() } return encryptorConfig{ MaxInstallations: 3, MaxSkip: 1000, MaxKeep: 3000, MaxMessageKeysPerSession: 2000, BundleRefreshInterval: 24 * 60 * 60 * 1000, InstallationID: installationID, Logger: logger, } } // newEncryptor creates a new EncryptionService instance. func newEncryptor(db *sql.DB, config encryptorConfig) *encryptor { return &encryptor{ persistence: newSQLitePersistence(db), config: config, messageIDs: make(map[string]*confirmationData), logger: config.Logger.With(zap.Namespace("encryptor")), } } func (s *encryptor) keyFromActiveX3DH(theirIdentityKey []byte, theirSignedPreKey []byte, myIdentityKey *ecdsa.PrivateKey) ([]byte, *ecdsa.PublicKey, error) { sharedKey, ephemeralPubKey, err := PerformActiveX3DH(theirIdentityKey, theirSignedPreKey, myIdentityKey) if err != nil { return nil, nil, err } return sharedKey, ephemeralPubKey, nil } func (s *encryptor) getDRSession(id []byte) (dr.Session, error) { sessionStorage := s.persistence.SessionStorage() return dr.Load( id, sessionStorage, dr.WithKeysStorage(s.persistence.KeysStorage()), dr.WithMaxSkip(s.config.MaxSkip), dr.WithMaxKeep(s.config.MaxKeep), dr.WithMaxMessageKeysPerSession(s.config.MaxMessageKeysPerSession), dr.WithCrypto(crypto.EthereumCrypto{}), ) } func confirmationIDString(id []byte) string { return hex.EncodeToString(id) } // ConfirmMessagesProcessed confirms and deletes message keys for the given messages func (s *encryptor) ConfirmMessageProcessed(messageID []byte) error { s.mutex.Lock() defer s.mutex.Unlock() id := confirmationIDString(messageID) confirmationData, ok := s.messageIDs[id] if !ok { s.logger.Debug("could not confirm message or message already confirmed", zap.String("messageID", id)) // We are ok with this, means no key material is stored (public message, or already confirmed) return nil } // Load session from store first session, err := s.getDRSession(confirmationData.drInfo.ID) if err != nil { return err } if err := session.DeleteMk(confirmationData.header.DH, confirmationData.header.N); err != nil { return err } // Clean up delete(s.messageIDs, id) return nil } // CreateBundle retrieves or creates an X3DH bundle given a private key func (s *encryptor) CreateBundle(privateKey *ecdsa.PrivateKey, installations []*multidevice.Installation) (*Bundle, error) { ourIdentityKeyC := ecrypto.CompressPubkey(&privateKey.PublicKey) bundleContainer, err := s.persistence.GetAnyPrivateBundle(ourIdentityKeyC, installations) if err != nil { return nil, err } expired := bundleContainer != nil && bundleContainer.GetBundle().Timestamp < time.Now().Add(-1*time.Duration(s.config.BundleRefreshInterval)*time.Millisecond).UnixNano() // If the bundle has expired we create a new one if expired { // Mark sessions has expired if err := s.persistence.MarkBundleExpired(bundleContainer.GetBundle().GetIdentity()); err != nil { return nil, err } } else if bundleContainer != nil { err = SignBundle(privateKey, bundleContainer) if err != nil { return nil, err } return bundleContainer.GetBundle(), nil } // needs transaction/mutex to avoid creating multiple bundles // although not a problem bundleContainer, err = NewBundleContainer(privateKey, s.config.InstallationID) if err != nil { return nil, err } if err = s.persistence.AddPrivateBundle(bundleContainer); err != nil { return nil, err } return s.CreateBundle(privateKey, installations) } // DecryptWithDH decrypts message sent with a DH key exchange, and throws away the key after decryption func (s *encryptor) DecryptWithDH(myIdentityKey *ecdsa.PrivateKey, theirEphemeralKey *ecdsa.PublicKey, payload []byte) ([]byte, error) { key, err := PerformDH( ecies.ImportECDSA(myIdentityKey), ecies.ImportECDSAPublic(theirEphemeralKey), ) if err != nil { return nil, err } return crypto.DecryptSymmetric(key, payload) } // keyFromPassiveX3DH decrypts message sent with a X3DH key exchange, storing the key for future exchanges func (s *encryptor) keyFromPassiveX3DH(myIdentityKey *ecdsa.PrivateKey, theirIdentityKey *ecdsa.PublicKey, theirEphemeralKey *ecdsa.PublicKey, ourBundleID []byte) ([]byte, error) { bundlePrivateKey, err := s.persistence.GetPrivateKeyBundle(ourBundleID) if err != nil { s.logger.Error("could not get private bundle", zap.Error(err)) return nil, err } if bundlePrivateKey == nil { return nil, errSessionNotFound } signedPreKey, err := ecrypto.ToECDSA(bundlePrivateKey) if err != nil { s.logger.Error("could not convert to ecdsa", zap.Error(err)) return nil, err } key, err := PerformPassiveX3DH( theirIdentityKey, signedPreKey, theirEphemeralKey, myIdentityKey, ) if err != nil { s.logger.Error("could not perform passive x3dh", zap.Error(err)) return nil, err } return key, nil } // ProcessPublicBundle persists a bundle func (s *encryptor) ProcessPublicBundle(myIdentityKey *ecdsa.PrivateKey, b *Bundle) error { return s.persistence.AddPublicBundle(b) } // DecryptPayload decrypts the payload of a DirectMessageProtocol, given an identity private key and the sender's public key func (s *encryptor) DecryptPayload(myIdentityKey *ecdsa.PrivateKey, theirIdentityKey *ecdsa.PublicKey, theirInstallationID string, msgs map[string]*DirectMessageProtocol, messageID []byte) ([]byte, error) { s.mutex.Lock() defer s.mutex.Unlock() msg := msgs[s.config.InstallationID] if msg == nil { msg = msgs[noInstallationID] } // We should not be sending a signal if it's coming from us, as we receive our own messages if msg == nil && !samePublicKeys(*theirIdentityKey, myIdentityKey.PublicKey) { return nil, ErrDeviceNotFound } else if msg == nil { return nil, ErrNotPairedDevice } payload := msg.GetPayload() if x3dhHeader := msg.GetX3DHHeader(); x3dhHeader != nil { bundleID := x3dhHeader.GetId() theirEphemeralKey, err := ecrypto.DecompressPubkey(x3dhHeader.GetKey()) if err != nil { return nil, err } symmetricKey, err := s.keyFromPassiveX3DH(myIdentityKey, theirIdentityKey, theirEphemeralKey, bundleID) if err != nil { return nil, err } theirIdentityKeyC := ecrypto.CompressPubkey(theirIdentityKey) err = s.persistence.AddRatchetInfo(symmetricKey, theirIdentityKeyC, bundleID, nil, theirInstallationID) if err != nil { return nil, err } } if drHeader := msg.GetDRHeader(); drHeader != nil { drMessage := &dr.Message{ Header: dr.MessageHeader{ N: drHeader.GetN(), PN: drHeader.GetPn(), DH: drHeader.GetKey(), }, Ciphertext: msg.GetPayload(), } theirIdentityKeyC := ecrypto.CompressPubkey(theirIdentityKey) drInfo, err := s.persistence.GetRatchetInfo(drHeader.GetId(), theirIdentityKeyC, theirInstallationID) if err != nil { s.logger.Error("could not get ratchet info", zap.Error(err)) return nil, err } // We mark the exchange as successful so we stop sending x3dh header if err = s.persistence.RatchetInfoConfirmed(drHeader.GetId(), theirIdentityKeyC, theirInstallationID); err != nil { s.logger.Error("could not confirm ratchet info", zap.Error(err)) return nil, err } if drInfo == nil { s.logger.Error("could not find a session") return nil, errSessionNotFound } confirmationData := &confirmationData{ header: &drMessage.Header, drInfo: drInfo, } s.messageIDs[confirmationIDString(messageID)] = confirmationData return s.decryptUsingDR(theirIdentityKey, drInfo, drMessage) } // Try DH if header := msg.GetDHHeader(); header != nil { decompressedKey, err := ecrypto.DecompressPubkey(header.GetKey()) if err != nil { return nil, err } return s.DecryptWithDH(myIdentityKey, decompressedKey, payload) } return nil, errors.New("no key specified") } func (s *encryptor) createNewSession(drInfo *RatchetInfo, sk []byte, keyPair crypto.DHPair) (dr.Session, error) { var err error var session dr.Session if drInfo.PrivateKey != nil { session, err = dr.New( drInfo.ID, sk, keyPair, s.persistence.SessionStorage(), dr.WithKeysStorage(s.persistence.KeysStorage()), dr.WithMaxSkip(s.config.MaxSkip), dr.WithMaxKeep(s.config.MaxKeep), dr.WithMaxMessageKeysPerSession(s.config.MaxMessageKeysPerSession), dr.WithCrypto(crypto.EthereumCrypto{})) } else { session, err = dr.NewWithRemoteKey( drInfo.ID, sk, keyPair.PubKey, s.persistence.SessionStorage(), dr.WithKeysStorage(s.persistence.KeysStorage()), dr.WithMaxSkip(s.config.MaxSkip), dr.WithMaxKeep(s.config.MaxKeep), dr.WithMaxMessageKeysPerSession(s.config.MaxMessageKeysPerSession), dr.WithCrypto(crypto.EthereumCrypto{})) } return session, err } func (s *encryptor) encryptUsingDR(theirIdentityKey *ecdsa.PublicKey, drInfo *RatchetInfo, payload []byte) ([]byte, *DRHeader, error) { var err error var session dr.Session keyPair := crypto.DHPair{ PrvKey: drInfo.PrivateKey, PubKey: drInfo.PublicKey, } // Load session from store first session, err = s.getDRSession(drInfo.ID) if err != nil { return nil, nil, err } // Create a new one if session == nil { session, err = s.createNewSession(drInfo, drInfo.Sk, keyPair) if err != nil { return nil, nil, err } } response, err := session.RatchetEncrypt(payload, nil) if err != nil { return nil, nil, err } header := &DRHeader{ Id: drInfo.BundleID, Key: response.Header.DH[:], N: response.Header.N, Pn: response.Header.PN, } return response.Ciphertext, header, nil } func (s *encryptor) decryptUsingDR(theirIdentityKey *ecdsa.PublicKey, drInfo *RatchetInfo, payload *dr.Message) ([]byte, error) { var err error var session dr.Session keyPair := crypto.DHPair{ PrvKey: drInfo.PrivateKey, PubKey: drInfo.PublicKey, } session, err = s.getDRSession(drInfo.ID) if err != nil { return nil, err } if session == nil { session, err = s.createNewSession(drInfo, drInfo.Sk, keyPair) if err != nil { return nil, err } } plaintext, err := session.RatchetDecrypt(*payload, nil) if err != nil { return nil, err } return plaintext, nil } func (s *encryptor) encryptWithDH(theirIdentityKey *ecdsa.PublicKey, payload []byte) (*DirectMessageProtocol, error) { symmetricKey, ourEphemeralKey, err := PerformActiveDH(theirIdentityKey) if err != nil { return nil, err } encryptedPayload, err := crypto.EncryptSymmetric(symmetricKey, payload) if err != nil { return nil, err } return &DirectMessageProtocol{ DHHeader: &DHHeader{ Key: ecrypto.CompressPubkey(ourEphemeralKey), }, Payload: encryptedPayload, }, nil } func (s *encryptor) EncryptPayloadWithDH(theirIdentityKey *ecdsa.PublicKey, payload []byte) (map[string]*DirectMessageProtocol, error) { response := make(map[string]*DirectMessageProtocol) dmp, err := s.encryptWithDH(theirIdentityKey, payload) if err != nil { return nil, err } response[noInstallationID] = dmp return response, nil } // GetPublicBundle returns the active installations bundles for a given user func (s *encryptor) GetPublicBundle(theirIdentityKey *ecdsa.PublicKey, installations []*multidevice.Installation) (*Bundle, error) { return s.persistence.GetPublicBundle(theirIdentityKey, installations) } // EncryptPayload returns a new DirectMessageProtocol with a given payload encrypted, given a recipient's public key and the sender private identity key func (s *encryptor) EncryptPayload(theirIdentityKey *ecdsa.PublicKey, myIdentityKey *ecdsa.PrivateKey, installations []*multidevice.Installation, payload []byte) (map[string]*DirectMessageProtocol, []*multidevice.Installation, error) { logger := s.logger.With( zap.String("site", "EncryptPayload"), zap.Binary("their-identity-key", ecrypto.FromECDSAPub(theirIdentityKey))) logger.Debug("encrypting payload") // Which installations we are sending the message to var targetedInstallations []*multidevice.Installation s.mutex.Lock() defer s.mutex.Unlock() // We don't have any, send a message with DH if len(installations) == 0 { logger.Debug("no installations, sending to all devices") encryptedPayload, err := s.EncryptPayloadWithDH(theirIdentityKey, payload) return encryptedPayload, targetedInstallations, err } theirIdentityKeyC := ecrypto.CompressPubkey(theirIdentityKey) response := make(map[string]*DirectMessageProtocol) for _, installation := range installations { installationID := installation.ID ilogger := logger.With(zap.String("installation-id", installationID)) ilogger.Debug("processing installation") if s.config.InstallationID == installationID { continue } bundle, err := s.persistence.GetPublicBundle(theirIdentityKey, []*multidevice.Installation{installation}) if err != nil { return nil, nil, err } // See if a session is there already drInfo, err := s.persistence.GetAnyRatchetInfo(theirIdentityKeyC, installationID) if err != nil { return nil, nil, err } targetedInstallations = append(targetedInstallations, installation) if drInfo != nil { ilogger.Debug("found DR info for installation") encryptedPayload, drHeader, err := s.encryptUsingDR(theirIdentityKey, drInfo, payload) if err != nil { return nil, nil, err } dmp := DirectMessageProtocol{ Payload: encryptedPayload, DRHeader: drHeader, } if drInfo.EphemeralKey != nil { dmp.X3DHHeader = &X3DHHeader{ Key: drInfo.EphemeralKey, Id: drInfo.BundleID, } } response[drInfo.InstallationID] = &dmp continue } theirSignedPreKeyContainer := bundle.GetSignedPreKeys()[installationID] // This should not be nil at this point if theirSignedPreKeyContainer == nil { ilogger.Warn("could not find DR info or bundle for installation") continue } ilogger.Debug("DR info not found, using bundle") theirSignedPreKey := theirSignedPreKeyContainer.GetSignedPreKey() sharedKey, ourEphemeralKey, err := s.keyFromActiveX3DH(theirIdentityKeyC, theirSignedPreKey, myIdentityKey) if err != nil { return nil, nil, err } theirIdentityKeyC := ecrypto.CompressPubkey(theirIdentityKey) ourEphemeralKeyC := ecrypto.CompressPubkey(ourEphemeralKey) err = s.persistence.AddRatchetInfo(sharedKey, theirIdentityKeyC, theirSignedPreKey, ourEphemeralKeyC, installationID) if err != nil { return nil, nil, err } x3dhHeader := &X3DHHeader{ Key: ourEphemeralKeyC, Id: theirSignedPreKey, } drInfo, err = s.persistence.GetRatchetInfo(theirSignedPreKey, theirIdentityKeyC, installationID) if err != nil { return nil, nil, err } if drInfo != nil { encryptedPayload, drHeader, err := s.encryptUsingDR(theirIdentityKey, drInfo, payload) if err != nil { return nil, nil, err } dmp := &DirectMessageProtocol{ Payload: encryptedPayload, X3DHHeader: x3dhHeader, DRHeader: drHeader, } response[drInfo.InstallationID] = dmp } } var installationIDs []string for _, i := range targetedInstallations { installationIDs = append(installationIDs, i.ID) } logger.Info( "built a message", zap.Strings("installation-ids", installationIDs), ) return response, targetedInstallations, nil } func samePublicKeys(pubKey1, pubKey2 ecdsa.PublicKey) bool { return pubKey1.X.Cmp(pubKey2.X) == 0 && pubKey1.Y.Cmp(pubKey2.Y) == 0 }