From c5f58afe71eb601bc9fdc963f7a328d3a6ec408f Mon Sep 17 00:00:00 2001
From: Gary Kramlich <grim@reaperworld.com>
Date: Wed, 20 Apr 2022 06:01:26 -0500
Subject: [PATCH] End to bridge encryption implementation

So far this is passing my basic tests, but could use some testing from people
that are much more familiar with how this is supposed to work.

Refs #27
---
 bridge/bridge.go                              |  31 ++
 bridge/commands.go                            |  11 +-
 bridge/crypto.go                              | 339 ++++++++++++++++++
 bridge/matrix.go                              | 119 ++++++
 bridge/portal.go                              |  77 +++-
 bridge/user.go                                |   3 +
 config/bridge.go                              |   2 +
 config/encryption.go                          |  29 ++
 database/cryptostore.go                       |  97 +++++
 .../08-add-crypto-store-to-database.sql       |   3 +
 .../09-add-account_id-to-crypto-store.sql     |   3 +
 ...d-megolm-withheld-data-to-crypto-store.sql |   3 +
 ...add-cross-signing-keys-to-crypto-store.sql |   3 +
 ...rchar-with-text-in-the-crypto-database.sql |   4 +
 ...ted-and-last_decrypted-in-crypto-store.sql |   4 +
 ...4-add-encrypted-column-to-portal-table.sql |   1 +
 database/migrations/migrations.go             | 109 ++++--
 database/portal.go                            |  16 +-
 database/portalquery.go                       |  16 +-
 database/sqlstatestore.go                     |  28 ++
 go.mod                                        |   4 +
 go.sum                                        |   4 +
 22 files changed, 848 insertions(+), 58 deletions(-)
 create mode 100644 bridge/crypto.go
 create mode 100644 config/encryption.go
 create mode 100644 database/cryptostore.go
 create mode 100644 database/migrations/08-add-crypto-store-to-database.sql
 create mode 100644 database/migrations/09-add-account_id-to-crypto-store.sql
 create mode 100644 database/migrations/10-add-megolm-withheld-data-to-crypto-store.sql
 create mode 100644 database/migrations/11-add-cross-signing-keys-to-crypto-store.sql
 create mode 100644 database/migrations/12-replace-varchar-with-text-in-the-crypto-database.sql
 create mode 100644 database/migrations/13-split-last_used-into-last_encrypted-and-last_decrypted-in-crypto-store.sql
 create mode 100644 database/migrations/14-add-encrypted-column-to-portal-table.sql

diff --git a/bridge/bridge.go b/bridge/bridge.go
index c1b09a9..31c5463 100644
--- a/bridge/bridge.go
+++ b/bridge/bridge.go
@@ -48,6 +48,8 @@ type Bridge struct {
 	puppetsLock         sync.Mutex
 
 	StateStore *database.SQLStateStore
+
+	crypto Crypto
 }
 
 func New(cfg *config.Config) (*Bridge, error) {
@@ -104,6 +106,8 @@ func New(cfg *config.Config) (*Bridge, error) {
 		StateStore: stateStore,
 	}
 
+	bridge.crypto = NewCryptoHelper(bridge)
+
 	if cfg.Appservice.Provisioning.Enabled() {
 		bridge.provisioning = newProvisioningAPI(bridge)
 	}
@@ -151,6 +155,13 @@ func (b *Bridge) Start() error {
 		return err
 	}
 
+	if b.crypto != nil {
+		if err := b.crypto.Init(); err != nil {
+			b.log.Fatalln("Error initializing end-to-bridge encryption:", err)
+			return err
+		}
+	}
+
 	b.log.Debugln("Starting application service HTTP server")
 	go b.as.Start()
 
@@ -159,6 +170,10 @@ func (b *Bridge) Start() error {
 
 	go b.updateBotProfile()
 
+	if b.crypto != nil {
+		go b.crypto.Start()
+	}
+
 	go b.startUsers()
 
 	// Finally tell the appservice we're ready
@@ -168,5 +183,21 @@ func (b *Bridge) Start() error {
 }
 
 func (b *Bridge) Stop() {
+	if b.crypto != nil {
+		b.crypto.Stop()
+	}
+
+	b.as.Stop()
+	b.eventProcessor.Stop()
+
+	for _, user := range b.usersByMXID {
+		if user.Session == nil {
+			continue
+		}
+
+		b.log.Debugln("Disconnecting", user.MXID)
+		user.Session.Close()
+	}
+
 	b.log.Infoln("Bridge stopped")
 }
diff --git a/bridge/commands.go b/bridge/commands.go
index 2799e7f..83363b6 100644
--- a/bridge/commands.go
+++ b/bridge/commands.go
@@ -3,6 +3,7 @@ package bridge
 import (
 	"context"
 	"fmt"
+	"time"
 
 	"github.com/alecthomas/kong"
 
@@ -33,11 +34,17 @@ func (g *globals) reply(msg string) {
 	content.MsgType = event.MsgNotice
 	intent := g.bot
 
-	if g.portal != nil && g.portal.IsPrivateChat() {
+	if g.portal == nil {
+		g.handler.log.Errorfln("we don't have a portal for this command")
+
+		return
+	}
+
+	if g.portal.IsPrivateChat() {
 		intent = g.portal.MainIntent()
 	}
 
-	_, err := intent.SendMessageEvent(g.roomID, event.EventMessage, content)
+	_, err := g.portal.sendMatrixMessage(intent, event.EventMessage, &content, nil, time.Now().UTC().UnixMilli())
 	if err != nil {
 		g.handler.log.Warnfln("Failed to reply to command from %q: %v", g.user.MXID, err)
 	}
diff --git a/bridge/crypto.go b/bridge/crypto.go
new file mode 100644
index 0000000..7c12eb3
--- /dev/null
+++ b/bridge/crypto.go
@@ -0,0 +1,339 @@
+package bridge
+
+import (
+	"fmt"
+	"runtime/debug"
+	"time"
+
+	"maunium.net/go/maulogger/v2"
+
+	"maunium.net/go/mautrix"
+	"maunium.net/go/mautrix/crypto"
+	"maunium.net/go/mautrix/event"
+	"maunium.net/go/mautrix/id"
+
+	"gitlab.com/beeper/discord/database"
+)
+
+var NoSessionFound = crypto.NoSessionFound
+
+var levelTrace = maulogger.Level{
+	Name:     "TRACE",
+	Severity: -10,
+	Color:    -1,
+}
+
+type Crypto interface {
+	HandleMemberEvent(*event.Event)
+	Decrypt(*event.Event) (*event.Event, error)
+	Encrypt(id.RoomID, event.Type, event.Content) (*event.EncryptedEventContent, error)
+	WaitForSession(id.RoomID, id.SenderKey, id.SessionID, time.Duration) bool
+	RequestSession(id.RoomID, id.SenderKey, id.SessionID, id.UserID, id.DeviceID)
+	ResetSession(id.RoomID)
+	Init() error
+	Start()
+	Stop()
+}
+
+type CryptoHelper struct {
+	bridge  *Bridge
+	client  *mautrix.Client
+	mach    *crypto.OlmMachine
+	store   *database.SQLCryptoStore
+	log     maulogger.Logger
+	baseLog maulogger.Logger
+}
+
+func NewCryptoHelper(bridge *Bridge) Crypto {
+	if !bridge.Config.Bridge.Encryption.Allow {
+		bridge.log.Debugln("Bridge built with end-to-bridge encryption, but disabled in config")
+		return nil
+	}
+
+	baseLog := bridge.log.Sub("Crypto")
+	return &CryptoHelper{
+		bridge:  bridge,
+		log:     baseLog.Sub("Helper"),
+		baseLog: baseLog,
+	}
+}
+
+func (helper *CryptoHelper) Init() error {
+	helper.log.Debugln("Initializing end-to-bridge encryption...")
+
+	helper.store = database.NewSQLCryptoStore(helper.bridge.db, helper.bridge.as.BotMXID(),
+		fmt.Sprintf("@%s:%s", helper.bridge.Config.Bridge.FormatUsername("%"), helper.bridge.as.HomeserverDomain))
+
+	var err error
+	helper.client, err = helper.loginBot()
+	if err != nil {
+		return err
+	}
+
+	helper.log.Debugln("Logged in as bridge bot with device ID", helper.client.DeviceID)
+
+	logger := &cryptoLogger{helper.baseLog}
+	stateStore := &cryptoStateStore{helper.bridge}
+	helper.mach = crypto.NewOlmMachine(helper.client, logger, helper.store, stateStore)
+	helper.mach.AllowKeyShare = helper.allowKeyShare
+
+	helper.client.Syncer = &cryptoSyncer{helper.mach}
+	helper.client.Store = &cryptoClientStore{helper.store}
+
+	return helper.mach.Load()
+}
+
+func (helper *CryptoHelper) allowKeyShare(device *crypto.DeviceIdentity, info event.RequestedKeyInfo) *crypto.KeyShareRejection {
+	cfg := helper.bridge.Config.Bridge.Encryption.KeySharing
+	if !cfg.Allow {
+		return &crypto.KeyShareRejectNoResponse
+	} else if device.Trust == crypto.TrustStateBlacklisted {
+		return &crypto.KeyShareRejectBlacklisted
+	} else if device.Trust == crypto.TrustStateVerified || !cfg.RequireVerification {
+		portal := helper.bridge.GetPortalByMXID(info.RoomID)
+		if portal == nil {
+			helper.log.Debugfln("Rejecting key request for %s from %s/%s: room is not a portal", info.SessionID, device.UserID, device.DeviceID)
+
+			return &crypto.KeyShareRejection{Code: event.RoomKeyWithheldUnavailable, Reason: "Requested room is not a portal room"}
+		}
+		user := helper.bridge.GetUserByMXID(device.UserID)
+		// FIXME reimplement IsInPortal
+		if !user.Admin /*&& !user.IsInPortal(portal.Key)*/ {
+			helper.log.Debugfln("Rejecting key request for %s from %s/%s: user is not in portal", info.SessionID, device.UserID, device.DeviceID)
+
+			return &crypto.KeyShareRejection{Code: event.RoomKeyWithheldUnauthorized, Reason: "You're not in that portal"}
+		}
+		helper.log.Debugfln("Accepting key request for %s from %s/%s", info.SessionID, device.UserID, device.DeviceID)
+
+		return nil
+	}
+
+	return &crypto.KeyShareRejectUnverified
+}
+
+func (helper *CryptoHelper) loginBot() (*mautrix.Client, error) {
+	deviceID := helper.store.FindDeviceID()
+	if len(deviceID) > 0 {
+		helper.log.Debugln("Found existing device ID for bot in database:", deviceID)
+	}
+
+	client, err := mautrix.NewClient(helper.bridge.as.HomeserverURL, "", "")
+	if err != nil {
+		return nil, fmt.Errorf("failed to initialize client: %w", err)
+	}
+
+	client.Logger = helper.baseLog.Sub("Bot")
+	client.Client = helper.bridge.as.HTTPClient
+	client.DefaultHTTPRetries = helper.bridge.as.DefaultHTTPRetries
+	flows, err := client.GetLoginFlows()
+	if err != nil {
+		return nil, fmt.Errorf("failed to get supported login flows: %w", err)
+	}
+
+	flow := flows.FirstFlowOfType(mautrix.AuthTypeAppservice, mautrix.AuthTypeHalfyAppservice)
+	if flow == nil {
+		return nil, fmt.Errorf("homeserver does not support appservice login")
+	}
+
+	// We set the API token to the AS token here to authenticate the appservice login
+	// It'll get overridden after the login
+	client.AccessToken = helper.bridge.as.Registration.AppToken
+	resp, err := client.Login(&mautrix.ReqLogin{
+		Type:                     flow.Type,
+		Identifier:               mautrix.UserIdentifier{Type: mautrix.IdentifierTypeUser, User: string(helper.bridge.as.BotMXID())},
+		DeviceID:                 deviceID,
+		InitialDeviceDisplayName: "Discord Bridge",
+		StoreCredentials:         true,
+	})
+	if err != nil {
+		return nil, fmt.Errorf("failed to log in as bridge bot: %w", err)
+	}
+
+	helper.store.DeviceID = resp.DeviceID
+
+	return client, nil
+}
+
+func (helper *CryptoHelper) Start() {
+	helper.log.Debugln("Starting syncer for receiving to-device messages")
+
+	err := helper.client.Sync()
+	if err != nil {
+		helper.log.Errorln("Fatal error syncing:", err)
+	} else {
+		helper.log.Infoln("Bridge bot to-device syncer stopped without error")
+	}
+}
+
+func (helper *CryptoHelper) Stop() {
+	helper.log.Debugln("CryptoHelper.Stop() called, stopping bridge bot sync")
+	helper.client.StopSync()
+}
+
+func (helper *CryptoHelper) Decrypt(evt *event.Event) (*event.Event, error) {
+	return helper.mach.DecryptMegolmEvent(evt)
+}
+
+func (helper *CryptoHelper) Encrypt(roomID id.RoomID, evtType event.Type, content event.Content) (*event.EncryptedEventContent, error) {
+	encrypted, err := helper.mach.EncryptMegolmEvent(roomID, evtType, &content)
+
+	if err != nil {
+		if err != crypto.SessionExpired && err != crypto.SessionNotShared && err != crypto.NoGroupSession {
+			return nil, err
+		}
+
+		helper.log.Debugfln("Got %v while encrypting event for %s, sharing group session and trying again...", err, roomID)
+		users, err := helper.store.GetRoomMembers(roomID)
+		if err != nil {
+			return nil, fmt.Errorf("failed to get room member list: %w", err)
+		}
+
+		err = helper.mach.ShareGroupSession(roomID, users)
+		if err != nil {
+			return nil, fmt.Errorf("failed to share group session: %w", err)
+		}
+
+		encrypted, err = helper.mach.EncryptMegolmEvent(roomID, evtType, &content)
+		if err != nil {
+			return nil, fmt.Errorf("failed to encrypt event after re-sharing group session: %w", err)
+		}
+	}
+
+	return encrypted, nil
+}
+
+func (helper *CryptoHelper) WaitForSession(roomID id.RoomID, senderKey id.SenderKey, sessionID id.SessionID, timeout time.Duration) bool {
+	return helper.mach.WaitForSession(roomID, senderKey, sessionID, timeout)
+}
+
+func (helper *CryptoHelper) RequestSession(roomID id.RoomID, senderKey id.SenderKey, sessionID id.SessionID, userID id.UserID, deviceID id.DeviceID) {
+	err := helper.mach.SendRoomKeyRequest(roomID, senderKey, sessionID, "", map[id.UserID][]id.DeviceID{userID: {deviceID}})
+	if err != nil {
+		helper.log.Warnfln("Failed to send key request to %s/%s for %s in %s: %v", userID, deviceID, sessionID, roomID, err)
+	} else {
+		helper.log.Debugfln("Sent key request to %s/%s for %s in %s", userID, deviceID, sessionID, roomID)
+	}
+}
+
+func (helper *CryptoHelper) ResetSession(roomID id.RoomID) {
+	err := helper.mach.CryptoStore.RemoveOutboundGroupSession(roomID)
+	if err != nil {
+		helper.log.Debugfln("Error manually removing outbound group session in %s: %v", roomID, err)
+	}
+}
+
+func (helper *CryptoHelper) HandleMemberEvent(evt *event.Event) {
+	helper.mach.HandleMemberEvent(evt)
+}
+
+type cryptoSyncer struct {
+	*crypto.OlmMachine
+}
+
+func (syncer *cryptoSyncer) ProcessResponse(resp *mautrix.RespSync, since string) error {
+	done := make(chan struct{})
+	go func() {
+		defer func() {
+			if err := recover(); err != nil {
+				syncer.Log.Error("Processing sync response (%s) panicked: %v\n%s", since, err, debug.Stack())
+			}
+			done <- struct{}{}
+		}()
+		syncer.Log.Trace("Starting sync response handling (%s)", since)
+		syncer.ProcessSyncResponse(resp, since)
+		syncer.Log.Trace("Successfully handled sync response (%s)", since)
+	}()
+
+	select {
+	case <-done:
+	case <-time.After(30 * time.Second):
+		syncer.Log.Warn("Handling sync response (%s) is taking unusually long", since)
+	}
+
+	return nil
+}
+
+func (syncer *cryptoSyncer) OnFailedSync(_ *mautrix.RespSync, err error) (time.Duration, error) {
+	syncer.Log.Error("Error /syncing, waiting 10 seconds: %v", err)
+
+	return 10 * time.Second, nil
+}
+
+func (syncer *cryptoSyncer) GetFilterJSON(_ id.UserID) *mautrix.Filter {
+	everything := []event.Type{{Type: "*"}}
+
+	return &mautrix.Filter{
+		Presence:    mautrix.FilterPart{NotTypes: everything},
+		AccountData: mautrix.FilterPart{NotTypes: everything},
+		Room: mautrix.RoomFilter{
+			IncludeLeave: false,
+			Ephemeral:    mautrix.FilterPart{NotTypes: everything},
+			AccountData:  mautrix.FilterPart{NotTypes: everything},
+			State:        mautrix.FilterPart{NotTypes: everything},
+			Timeline:     mautrix.FilterPart{NotTypes: everything},
+		},
+	}
+}
+
+type cryptoLogger struct {
+	int maulogger.Logger
+}
+
+func (c *cryptoLogger) Error(message string, args ...interface{}) {
+	c.int.Errorfln(message, args...)
+}
+
+func (c *cryptoLogger) Warn(message string, args ...interface{}) {
+	c.int.Warnfln(message, args...)
+}
+
+func (c *cryptoLogger) Debug(message string, args ...interface{}) {
+	c.int.Debugfln(message, args...)
+}
+
+func (c *cryptoLogger) Trace(message string, args ...interface{}) {
+	c.int.Logfln(levelTrace, message, args...)
+}
+
+type cryptoClientStore struct {
+	int *database.SQLCryptoStore
+}
+
+func (c cryptoClientStore) SaveFilterID(_ id.UserID, _ string) {}
+func (c cryptoClientStore) LoadFilterID(_ id.UserID) string    { return "" }
+func (c cryptoClientStore) SaveRoom(_ *mautrix.Room)           {}
+func (c cryptoClientStore) LoadRoom(_ id.RoomID) *mautrix.Room { return nil }
+
+func (c cryptoClientStore) SaveNextBatch(_ id.UserID, nextBatchToken string) {
+	c.int.PutNextBatch(nextBatchToken)
+}
+
+func (c cryptoClientStore) LoadNextBatch(_ id.UserID) string {
+	return c.int.GetNextBatch()
+}
+
+var _ mautrix.Storer = (*cryptoClientStore)(nil)
+
+type cryptoStateStore struct {
+	bridge *Bridge
+}
+
+var _ crypto.StateStore = (*cryptoStateStore)(nil)
+
+func (c *cryptoStateStore) IsEncrypted(id id.RoomID) bool {
+	portal := c.bridge.GetPortalByMXID(id)
+	if portal != nil {
+		return portal.Encrypted
+	}
+
+	return false
+}
+
+func (c *cryptoStateStore) FindSharedRooms(id id.UserID) []id.RoomID {
+	return c.bridge.StateStore.FindSharedRooms(id)
+}
+
+func (c *cryptoStateStore) GetEncryptionEvent(id.RoomID) *event.EncryptionEventContent {
+	// TODO implement
+	return nil
+}
diff --git a/bridge/matrix.go b/bridge/matrix.go
index 4e88f18..cb9127e 100644
--- a/bridge/matrix.go
+++ b/bridge/matrix.go
@@ -1,7 +1,10 @@
 package bridge
 
 import (
+	"errors"
+	"fmt"
 	"strings"
+	"time"
 
 	"maunium.net/go/maulogger/v2"
 	"maunium.net/go/mautrix"
@@ -29,9 +32,11 @@ func (b *Bridge) setupEvents() {
 	}
 
 	b.eventProcessor.On(event.EventMessage, b.matrixHandler.handleMessage)
+	b.eventProcessor.On(event.EventEncrypted, b.matrixHandler.handleEncrypted)
 	b.eventProcessor.On(event.EventReaction, b.matrixHandler.handleReaction)
 	b.eventProcessor.On(event.EventRedaction, b.matrixHandler.handleRedaction)
 	b.eventProcessor.On(event.StateMember, b.matrixHandler.handleMembership)
+	b.eventProcessor.On(event.StateEncryption, b.matrixHandler.handleEncryption)
 }
 
 func (mh *matrixHandler) join(evt *event.Event, intent *appservice.IntentAPI) *mautrix.RespJoinedMembers {
@@ -185,6 +190,10 @@ func (mh *matrixHandler) handleMembership(evt *event.Event) {
 		return
 	}
 
+	if mh.bridge.crypto != nil {
+		mh.bridge.crypto.HandleMemberEvent(evt)
+	}
+
 	// Grab the content of the event.
 	content := evt.Content.AsMember()
 
@@ -255,3 +264,113 @@ func (mh *matrixHandler) handleRedaction(evt *event.Event) {
 		portal.handleMatrixRedaction(evt)
 	}
 }
+
+func (mh *matrixHandler) handleEncryption(evt *event.Event) {
+	if evt.Content.AsEncryption().Algorithm != id.AlgorithmMegolmV1 {
+		return
+	}
+
+	portal := mh.bridge.GetPortalByMXID(evt.RoomID)
+	if portal != nil && !portal.Encrypted {
+		mh.log.Debugfln("%s enabled encryption in %s", evt.Sender, evt.RoomID)
+		portal.Encrypted = true
+		portal.Update()
+	}
+}
+
+const sessionWaitTimeout = 5 * time.Second
+
+func (mh *matrixHandler) handleEncrypted(evt *event.Event) {
+	if mh.ignoreEvent(evt) || mh.bridge.crypto == nil {
+		return
+	}
+
+	decrypted, err := mh.bridge.crypto.Decrypt(evt)
+	decryptionRetryCount := 0
+	if errors.Is(err, NoSessionFound) {
+		content := evt.Content.AsEncrypted()
+		mh.log.Debugfln("Couldn't find session %s trying to decrypt %s, waiting %d seconds...", content.SessionID, evt.ID, int(sessionWaitTimeout.Seconds()))
+		mh.as.SendErrorMessageSendCheckpoint(evt, appservice.StepDecrypted, err, false, decryptionRetryCount)
+		decryptionRetryCount++
+
+		if mh.bridge.crypto.WaitForSession(evt.RoomID, content.SenderKey, content.SessionID, sessionWaitTimeout) {
+			mh.log.Debugfln("Got session %s after waiting, trying to decrypt %s again", content.SessionID, evt.ID)
+			decrypted, err = mh.bridge.crypto.Decrypt(evt)
+		} else {
+			mh.as.SendErrorMessageSendCheckpoint(evt, appservice.StepDecrypted, fmt.Errorf("didn't receive encryption keys"), false, decryptionRetryCount)
+
+			go mh.waitLongerForSession(evt)
+
+			return
+		}
+	}
+
+	if err != nil {
+		mh.as.SendErrorMessageSendCheckpoint(evt, appservice.StepDecrypted, err, true, decryptionRetryCount)
+
+		mh.log.Warnfln("Failed to decrypt %s: %v", evt.ID, err)
+		_, _ = mh.bridge.bot.SendNotice(evt.RoomID, fmt.Sprintf(
+			"\u26a0 Your message was not bridged: %v", err))
+
+		return
+	}
+
+	mh.as.SendMessageSendCheckpoint(decrypted, appservice.StepDecrypted, decryptionRetryCount)
+	mh.bridge.eventProcessor.Dispatch(decrypted)
+}
+
+func (mh *matrixHandler) waitLongerForSession(evt *event.Event) {
+	const extendedTimeout = sessionWaitTimeout * 3
+
+	content := evt.Content.AsEncrypted()
+	mh.log.Debugfln("Couldn't find session %s trying to decrypt %s, waiting %d more seconds...",
+		content.SessionID, evt.ID, int(extendedTimeout.Seconds()))
+
+	go mh.bridge.crypto.RequestSession(evt.RoomID, content.SenderKey, content.SessionID, evt.Sender, content.DeviceID)
+
+	resp, err := mh.bridge.bot.SendNotice(evt.RoomID, fmt.Sprintf(
+		"\u26a0 Your message was not bridged: the bridge hasn't received the decryption keys. "+
+			"The bridge will retry for %d seconds. If this error keeps happening, try restarting your client.",
+		int(extendedTimeout.Seconds())))
+	if err != nil {
+		mh.log.Errorfln("Failed to send decryption error to %s: %v", evt.RoomID, err)
+	}
+
+	update := event.MessageEventContent{MsgType: event.MsgNotice}
+
+	if mh.bridge.crypto.WaitForSession(evt.RoomID, content.SenderKey, content.SessionID, extendedTimeout) {
+		mh.log.Debugfln("Got session %s after waiting more, trying to decrypt %s again", content.SessionID, evt.ID)
+
+		decrypted, err := mh.bridge.crypto.Decrypt(evt)
+		if err == nil {
+			mh.as.SendMessageSendCheckpoint(decrypted, appservice.StepDecrypted, 2)
+			mh.bridge.eventProcessor.Dispatch(decrypted)
+			_, _ = mh.bridge.bot.RedactEvent(evt.RoomID, resp.EventID)
+
+			return
+		}
+
+		mh.log.Warnfln("Failed to decrypt %s: %v", evt.ID, err)
+		mh.as.SendErrorMessageSendCheckpoint(evt, appservice.StepDecrypted, err, true, 2)
+		update.Body = fmt.Sprintf("\u26a0 Your message was not bridged: %v", err)
+	} else {
+		mh.log.Debugfln("Didn't get %s, giving up on %s", content.SessionID, evt.ID)
+		mh.as.SendErrorMessageSendCheckpoint(evt, appservice.StepDecrypted, fmt.Errorf("didn't receive encryption keys"), true, 2)
+		update.Body = "\u26a0 Your message was not bridged: the bridge hasn't received the decryption keys. " +
+			"If this error keeps happening, try restarting your client."
+	}
+
+	newContent := update
+	update.NewContent = &newContent
+	if resp != nil {
+		update.RelatesTo = &event.RelatesTo{
+			Type:    event.RelReplace,
+			EventID: resp.EventID,
+		}
+	}
+
+	_, err = mh.bridge.bot.SendMessageEvent(evt.RoomID, event.EventMessage, &update)
+	if err != nil {
+		mh.log.Debugfln("Failed to update decryption error notice %s: %v", resp.EventID, err)
+	}
+}
diff --git a/bridge/portal.go b/bridge/portal.go
index 05562d3..2eed2ef 100644
--- a/bridge/portal.go
+++ b/bridge/portal.go
@@ -35,6 +35,7 @@ type Portal struct {
 	log    log.Logger
 
 	roomCreateLock sync.Mutex
+	encryptLock    sync.Mutex
 
 	discordMessages chan portalDiscordMessage
 	matrixMessages  chan portalMatrixMessage
@@ -144,7 +145,7 @@ func (p *Portal) handleMatrixInvite(sender *User, evt *event.Event) {
 		p.log.Infoln("no puppet for %v", sender)
 		// Open a conversation on the discord side?
 	}
-	p.log.Infoln("puppet:", puppet)
+	p.log.Infoln("matrixInvite: puppet:", puppet)
 }
 
 func (p *Portal) messageLoop() {
@@ -212,14 +213,25 @@ func (p *Portal) createMatrixRoom(user *User, channel *discordgo.Channel) error
 
 	var invite []id.UserID
 
-	if p.IsPrivateChat() {
-		invite = append(invite, p.bridge.bot.UserID)
+	if p.bridge.Config.Bridge.Encryption.Default {
+		initialState = append(initialState, &event.Event{
+			Type: event.StateEncryption,
+			Content: event.Content{
+				Parsed: event.EncryptionEventContent{Algorithm: id.AlgorithmMegolmV1},
+			},
+		})
+		p.Encrypted = true
+
+		if p.IsPrivateChat() {
+			invite = append(invite, p.bridge.bot.UserID)
+		}
 	}
 
 	resp, err := intent.CreateRoom(&mautrix.ReqCreateRoom{
 		Visibility:      "private",
 		Name:            p.Name,
 		Topic:           p.Topic,
+		Invite:          invite,
 		Preset:          "private_chat",
 		IsDirect:        p.IsPrivateChat(),
 		InitialState:    initialState,
@@ -325,7 +337,7 @@ func (p *Portal) sendMediaFailedMessage(intent *appservice.IntentAPI, bridgeErr
 		MsgType: event.MsgNotice,
 	}
 
-	_, err := intent.SendMessageEvent(p.MXID, event.EventMessage, content)
+	_, err := p.sendMatrixMessage(intent, event.EventMessage, content, nil, time.Now().UTC().UnixMilli())
 	if err != nil {
 		p.log.Warnfln("failed to send error message to matrix: %v", err)
 	}
@@ -379,7 +391,7 @@ func (p *Portal) handleDiscordAttachment(intent *appservice.IntentAPI, msgID str
 		return
 	}
 
-	resp, err := intent.SendMessageEvent(p.MXID, event.EventMessage, content)
+	resp, err := p.sendMatrixMessage(intent, event.EventMessage, content, nil, time.Now().UTC().UnixMilli())
 	if err != nil {
 		p.log.Warnfln("failed to send media message to matrix: %v", err)
 	}
@@ -426,7 +438,7 @@ func (p *Portal) handleDiscordMessageCreate(user *User, msg *discordgo.Message)
 			}
 		}
 
-		resp, err := intent.SendMessageEvent(p.MXID, event.EventMessage, content)
+		resp, err := p.sendMatrixMessage(intent, event.EventMessage, content, nil, time.Now().UTC().UnixMilli())
 		if err != nil {
 			p.log.Warnfln("failed to send message %q to matrix: %v", msg.ID, err)
 
@@ -498,7 +510,7 @@ func (p *Portal) handleDiscordMessagesUpdate(user *User, msg *discordgo.Message)
 
 	content.SetEdit(existing.MatrixID)
 
-	resp, err := intent.SendMessageEvent(p.MXID, event.EventMessage, content)
+	resp, err := p.sendMatrixMessage(intent, event.EventMessage, content, nil, time.Now().UTC().UnixMilli())
 	if err != nil {
 		p.log.Warnfln("failed to send message %q to matrix: %v", msg.ID, err)
 
@@ -567,6 +579,57 @@ func (p *Portal) syncParticipants(source *User, participants []*discordgo.User)
 	}
 }
 
+func (portal *Portal) encrypt(content *event.Content, eventType event.Type) (event.Type, error) {
+	if portal.Encrypted && portal.bridge.crypto != nil {
+		// TODO maybe the locking should be inside mautrix-go?
+		portal.encryptLock.Lock()
+		encrypted, err := portal.bridge.crypto.Encrypt(portal.MXID, eventType, *content)
+		portal.encryptLock.Unlock()
+		if err != nil {
+			return eventType, fmt.Errorf("failed to encrypt event: %w", err)
+		}
+		eventType = event.EventEncrypted
+		content.Parsed = encrypted
+	}
+	return eventType, nil
+}
+
+const doublePuppetKey = "fi.mau.double_puppet_source"
+const doublePuppetValue = "mautrix-discord"
+
+func (portal *Portal) sendMatrixMessage(intent *appservice.IntentAPI, eventType event.Type, content *event.MessageEventContent, extraContent map[string]interface{}, timestamp int64) (*mautrix.RespSendEvent, error) {
+	wrappedContent := event.Content{Parsed: content, Raw: extraContent}
+	if timestamp != 0 && intent.IsCustomPuppet {
+		if wrappedContent.Raw == nil {
+			wrappedContent.Raw = map[string]interface{}{}
+		}
+		if intent.IsCustomPuppet {
+			wrappedContent.Raw[doublePuppetKey] = doublePuppetValue
+		}
+	}
+	var err error
+	eventType, err = portal.encrypt(&wrappedContent, eventType)
+	if err != nil {
+		return nil, err
+	}
+
+	if eventType == event.EventEncrypted {
+		// Clear other custom keys if the event was encrypted, but keep the double puppet identifier
+		if intent.IsCustomPuppet {
+			wrappedContent.Raw = map[string]interface{}{doublePuppetKey: doublePuppetValue}
+		} else {
+			wrappedContent.Raw = nil
+		}
+	}
+
+	_, _ = intent.UserTyping(portal.MXID, false, 0)
+	if timestamp == 0 {
+		return intent.SendMessageEvent(portal.MXID, eventType, &wrappedContent)
+	} else {
+		return intent.SendMassagedMessageEvent(portal.MXID, eventType, &wrappedContent, timestamp)
+	}
+}
+
 func (p *Portal) handleMatrixMessages(msg portalMatrixMessage) {
 	switch msg.evt.Type {
 	case event.EventMessage:
diff --git a/bridge/user.go b/bridge/user.go
index 1dcb262..bf35510 100644
--- a/bridge/user.go
+++ b/bridge/user.go
@@ -32,6 +32,9 @@ type User struct {
 	bridge *Bridge
 	log    log.Logger
 
+	// TODO finish implementing
+	Admin bool
+
 	guilds     map[string]*database.Guild
 	guildsLock sync.Mutex
 
diff --git a/config/bridge.go b/config/bridge.go
index 9d0510c..ce863db 100644
--- a/config/bridge.go
+++ b/config/bridge.go
@@ -30,6 +30,8 @@ type bridge struct {
 	DoublePuppetAllowDiscovery bool              `yaml:"double_puppet_allow_discovery"`
 	LoginSharedSecretMap       map[string]string `yaml:"login_shared_secret_map"`
 
+	Encryption encryption `yaml:"encryption"`
+
 	usernameTemplate    *template.Template `yaml:"-"`
 	displaynameTemplate *template.Template `yaml:"-"`
 	channelnameTemplate *template.Template `yaml:"-"`
diff --git a/config/encryption.go b/config/encryption.go
new file mode 100644
index 0000000..1d57c39
--- /dev/null
+++ b/config/encryption.go
@@ -0,0 +1,29 @@
+package config
+
+type encryption struct {
+	Allow   bool `yaml:"allow"`
+	Default bool `yaml:"default"`
+
+	KeySharing struct {
+		Allow               bool `yaml:"allow"`
+		RequireCrossSigning bool `yaml:"require_cross_signing"`
+		RequireVerification bool `yaml:"require_verification"`
+	} `yaml:"key_sharing"`
+}
+
+func (e *encryption) validate() error {
+	return nil
+}
+
+func (e *encryption) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	type rawEncryption encryption
+
+	raw := rawEncryption{}
+	if err := unmarshal(&raw); err != nil {
+		return err
+	}
+
+	*e = encryption(raw)
+
+	return e.validate()
+}
diff --git a/database/cryptostore.go b/database/cryptostore.go
new file mode 100644
index 0000000..171c824
--- /dev/null
+++ b/database/cryptostore.go
@@ -0,0 +1,97 @@
+package database
+
+import (
+	"database/sql"
+
+	log "maunium.net/go/maulogger/v2"
+
+	"maunium.net/go/mautrix/crypto"
+	"maunium.net/go/mautrix/id"
+)
+
+type SQLCryptoStore struct {
+	*crypto.SQLCryptoStore
+	UserID        id.UserID
+	GhostIDFormat string
+}
+
+var _ crypto.Store = (*SQLCryptoStore)(nil)
+
+func NewSQLCryptoStore(db *Database, userID id.UserID, ghostIDFormat string) *SQLCryptoStore {
+	return &SQLCryptoStore{
+		SQLCryptoStore: crypto.NewSQLCryptoStore(db.DB, db.dialect, "", "",
+			[]byte("maunium.net/go/mautrix-whatsapp"),
+			&cryptoLogger{db.log.Sub("CryptoStore")}),
+		UserID:        userID,
+		GhostIDFormat: ghostIDFormat,
+	}
+}
+
+func (store *SQLCryptoStore) FindDeviceID() id.DeviceID {
+	var deviceID id.DeviceID
+
+	query := `SELECT device_id FROM crypto_account WHERE account_id=$1`
+	err := store.DB.QueryRow(query, store.AccountID).Scan(&deviceID)
+	if err != nil && err != sql.ErrNoRows {
+		store.Log.Warn("Failed to scan device ID: %v", err)
+	}
+
+	return deviceID
+}
+
+func (store *SQLCryptoStore) GetRoomMembers(roomID id.RoomID) ([]id.UserID, error) {
+	query := `
+		SELECT user_id FROM mx_user_profile
+		WHERE room_id=$1
+			AND (membership='join' OR membership='invite')
+			AND user_id<>$2
+			AND user_id NOT LIKE $3
+	`
+
+	members := []id.UserID{}
+
+	rows, err := store.DB.Query(query, roomID, store.UserID, store.GhostIDFormat)
+	if err != nil {
+		return members, err
+	}
+
+	for rows.Next() {
+		var userID id.UserID
+		err := rows.Scan(&userID)
+		if err != nil {
+			store.Log.Warn("Failed to scan member in %s: %v", roomID, err)
+			return members, err
+		}
+
+		members = append(members, userID)
+	}
+
+	return members, nil
+}
+
+// TODO merge this with the one in the parent package
+type cryptoLogger struct {
+	int log.Logger
+}
+
+var levelTrace = log.Level{
+	Name:     "TRACE",
+	Severity: -10,
+	Color:    -1,
+}
+
+func (c *cryptoLogger) Error(message string, args ...interface{}) {
+	c.int.Errorfln(message, args...)
+}
+
+func (c *cryptoLogger) Warn(message string, args ...interface{}) {
+	c.int.Warnfln(message, args...)
+}
+
+func (c *cryptoLogger) Debug(message string, args ...interface{}) {
+	c.int.Debugfln(message, args...)
+}
+
+func (c *cryptoLogger) Trace(message string, args ...interface{}) {
+	c.int.Logfln(levelTrace, message, args...)
+}
diff --git a/database/migrations/08-add-crypto-store-to-database.sql b/database/migrations/08-add-crypto-store-to-database.sql
new file mode 100644
index 0000000..c615976
--- /dev/null
+++ b/database/migrations/08-add-crypto-store-to-database.sql
@@ -0,0 +1,3 @@
+-- This migration is implemented in migrations.go as it comes from
+-- maunium.net/go/mautrix/crypto/sql_store_upgrade. It runs upgrade at index 0
+-- which is described as "Add crypto store to database".
diff --git a/database/migrations/09-add-account_id-to-crypto-store.sql b/database/migrations/09-add-account_id-to-crypto-store.sql
new file mode 100644
index 0000000..03dc1cc
--- /dev/null
+++ b/database/migrations/09-add-account_id-to-crypto-store.sql
@@ -0,0 +1,3 @@
+-- This migration is implemented in migrations.go as it comes from
+-- maunium.net/go/mautrix/crypto/sql_store_upgrade. It runs upgrade at index 1
+-- which is described as "Add account_id to crypto store".
diff --git a/database/migrations/10-add-megolm-withheld-data-to-crypto-store.sql b/database/migrations/10-add-megolm-withheld-data-to-crypto-store.sql
new file mode 100644
index 0000000..38813b8
--- /dev/null
+++ b/database/migrations/10-add-megolm-withheld-data-to-crypto-store.sql
@@ -0,0 +1,3 @@
+-- This migration is implemented in migrations.go as it comes from
+-- maunium.net/go/mautrix/crypto/sql_store_upgrade. It runs upgrade at index 2
+-- which is described as "Add megolm withheld data to crypto store".
diff --git a/database/migrations/11-add-cross-signing-keys-to-crypto-store.sql b/database/migrations/11-add-cross-signing-keys-to-crypto-store.sql
new file mode 100644
index 0000000..39f5041
--- /dev/null
+++ b/database/migrations/11-add-cross-signing-keys-to-crypto-store.sql
@@ -0,0 +1,3 @@
+-- This migration is implemented in migrations.go as it comes from
+-- maunium.net/go/mautrix/crypto/sql_store_upgrade. It runs upgrade at index 3
+-- which is described as "Add cross-signing keys to crypto store".
diff --git a/database/migrations/12-replace-varchar-with-text-in-the-crypto-database.sql b/database/migrations/12-replace-varchar-with-text-in-the-crypto-database.sql
new file mode 100644
index 0000000..adb841e
--- /dev/null
+++ b/database/migrations/12-replace-varchar-with-text-in-the-crypto-database.sql
@@ -0,0 +1,4 @@
+-- This migration is implemented in migrations.go as it comes from
+-- maunium.net/go/mautrix/crypto/sql_store_upgrade. It runs upgrade at index 4
+-- which is described as "Replace VARCHAR(255) with TEXT in the crypto
+-- database".
diff --git a/database/migrations/13-split-last_used-into-last_encrypted-and-last_decrypted-in-crypto-store.sql b/database/migrations/13-split-last_used-into-last_encrypted-and-last_decrypted-in-crypto-store.sql
new file mode 100644
index 0000000..28906bd
--- /dev/null
+++ b/database/migrations/13-split-last_used-into-last_encrypted-and-last_decrypted-in-crypto-store.sql
@@ -0,0 +1,4 @@
+-- This migration is implemented in migrations.go as it comes from
+-- maunium.net/go/mautrix/crypto/sql_store_upgrade. It runs upgrade at index 5
+-- which is described as "Split last_used into last_encrypted and
+-- last_decrypted in crypto store".
diff --git a/database/migrations/14-add-encrypted-column-to-portal-table.sql b/database/migrations/14-add-encrypted-column-to-portal-table.sql
new file mode 100644
index 0000000..d032fee
--- /dev/null
+++ b/database/migrations/14-add-encrypted-column-to-portal-table.sql
@@ -0,0 +1 @@
+ALTER TABLE portal ADD COLUMN encrypted BOOLEAN NOT NULL DEFAULT false;
diff --git a/database/migrations/migrations.go b/database/migrations/migrations.go
index 06fcce4..904b9f4 100644
--- a/database/migrations/migrations.go
+++ b/database/migrations/migrations.go
@@ -3,37 +3,18 @@ package migrations
 import (
 	"database/sql"
 	"embed"
-	"sort"
 
 	"github.com/lopezator/migrator"
 	log "maunium.net/go/maulogger/v2"
+	"maunium.net/go/mautrix/crypto/sql_store_upgrade"
 )
 
 //go:embed *.sql
 var embeddedMigrations embed.FS
 
-var (
-	commonMigrations = []string{
-		"01-initial.sql",
-		"02-attachments.sql",
-		"03-emoji.sql",
-		"04-custom-puppet.sql",
-		"05-additional-puppet-fields.sql",
-		"07-guilds.sql",
-	}
-
-	sqliteMigrations = []string{
-		"06-remove-unique-user-constraint.sqlite.sql",
-	}
-
-	postgresMigrations = []string{
-		"06-remove-unique-user-constraint.postgres.sql",
-	}
-)
-
-func migrationFromFile(filename string) *migrator.Migration {
+func migrationFromFile(description, filename string) *migrator.Migration {
 	return &migrator.Migration{
-		Name: filename,
+		Name: description,
 		Func: func(tx *sql.Tx) error {
 			data, err := embeddedMigrations.ReadFile(filename)
 			if err != nil {
@@ -49,31 +30,83 @@ func migrationFromFile(filename string) *migrator.Migration {
 	}
 }
 
+func migrationFromFileWithDialect(dialect, description, sqliteFile, postgresFile string) *migrator.Migration {
+	switch dialect {
+	case "sqlite3":
+		return migrationFromFile(description, sqliteFile)
+	case "postgres":
+		return migrationFromFile(description, postgresFile)
+	default:
+		return nil
+	}
+}
+
 func Run(db *sql.DB, baseLog log.Logger, dialect string) error {
 	subLogger := baseLog.Sub("Migrations")
 	logger := migrator.LoggerFunc(func(msg string, args ...interface{}) {
 		subLogger.Infof(msg, args...)
 	})
 
-	migrationNames := commonMigrations
-	switch dialect {
-	case "sqlite3":
-		migrationNames = append(migrationNames, sqliteMigrations...)
-	case "postgres":
-		migrationNames = append(migrationNames, postgresMigrations...)
-	}
-
-	sort.Strings(migrationNames)
-
-	migrations := make([]interface{}, len(migrationNames))
-	for idx, name := range migrationNames {
-		migrations[idx] = migrationFromFile(name)
-	}
-
 	m, err := migrator.New(
 		migrator.TableName("version"),
 		migrator.WithLogger(logger),
-		migrator.Migrations(migrations...),
+		migrator.Migrations(
+			migrationFromFile("Initial Schema", "01-initial.sql"),
+			migrationFromFile("Attachments", "02-attachments.sql"),
+			migrationFromFile("Emoji", "03-emoji.sql"),
+			migrationFromFile("Custom Puppets", "04-custom-puppet.sql"),
+			migrationFromFile(
+				"Additional puppet fields",
+				"05-additional-puppet-fields.sql",
+			),
+			migrationFromFileWithDialect(
+				dialect,
+				"Remove unique user constraint",
+				"06-remove-unique-user-constraint.sqlite.sql",
+				"06-remove-unique-user-constraint.postgres.sql",
+			),
+			migrationFromFile("Guild Bridging", "07-guilds.sql"),
+			&migrator.Migration{
+				Name: "Add crypto store to database",
+				Func: func(tx *sql.Tx) error {
+					return sql_store_upgrade.Upgrades[0](tx, dialect)
+				},
+			},
+			&migrator.Migration{
+				Name: "Add account_id to crypto store",
+				Func: func(tx *sql.Tx) error {
+					return sql_store_upgrade.Upgrades[1](tx, dialect)
+				},
+			},
+			&migrator.Migration{
+				Name: "Add megolm withheld data to crypto store",
+				Func: func(tx *sql.Tx) error {
+					return sql_store_upgrade.Upgrades[2](tx, dialect)
+				},
+			},
+			&migrator.Migration{
+				Name: "Add cross-signing keys to crypto store",
+				Func: func(tx *sql.Tx) error {
+					return sql_store_upgrade.Upgrades[3](tx, dialect)
+				},
+			},
+			&migrator.Migration{
+				Name: "Replace VARCHAR(255) with TEXT in the crypto database",
+				Func: func(tx *sql.Tx) error {
+					return sql_store_upgrade.Upgrades[4](tx, dialect)
+				},
+			},
+			&migrator.Migration{
+				Name: "Split last_used into last_encrypted and last_decrypted in crypto store",
+				Func: func(tx *sql.Tx) error {
+					return sql_store_upgrade.Upgrades[5](tx, dialect)
+				},
+			},
+			migrationFromFile(
+				"Add encryption column to portal table",
+				"14-add-encrypted-column-to-portal-table.sql",
+			),
+		),
 	)
 	if err != nil {
 		return err
diff --git a/database/portal.go b/database/portal.go
index 663651b..96e4c45 100644
--- a/database/portal.go
+++ b/database/portal.go
@@ -19,6 +19,8 @@ type Portal struct {
 	Name  string
 	Topic string
 
+	Encrypted bool
+
 	Avatar    string
 	AvatarURL id.ContentURI
 
@@ -33,7 +35,8 @@ func (p *Portal) Scan(row Scannable) *Portal {
 	var typ sql.NullInt32
 
 	err := row.Scan(&p.Key.ChannelID, &p.Key.Receiver, &mxid, &p.Name,
-		&p.Topic, &p.Avatar, &avatarURL, &typ, &p.DMUser, &firstEventID)
+		&p.Topic, &p.Avatar, &avatarURL, &typ, &p.DMUser, &firstEventID,
+		&p.Encrypted)
 
 	if err != nil {
 		if err != sql.ErrNoRows {
@@ -62,12 +65,12 @@ func (p *Portal) mxidPtr() *id.RoomID {
 func (p *Portal) Insert() {
 	query := "INSERT INTO portal" +
 		" (channel_id, receiver, mxid, name, topic, avatar, avatar_url," +
-		" type, dmuser, first_event_id)" +
-		" VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10)"
+		" type, dmuser, first_event_id, encrypted)" +
+		" VALUES ($1, $2, $3, $4, $5, $6, $7, $8, $9, $10, $11)"
 
 	_, err := p.db.Exec(query, p.Key.ChannelID, p.Key.Receiver, p.mxidPtr(),
 		p.Name, p.Topic, p.Avatar, p.AvatarURL.String(), p.Type, p.DMUser,
-		p.FirstEventID.String())
+		p.FirstEventID.String(), p.Encrypted)
 
 	if err != nil {
 		p.log.Warnfln("Failed to insert %s: %v", p.Key, err)
@@ -77,11 +80,12 @@ func (p *Portal) Insert() {
 func (p *Portal) Update() {
 	query := "UPDATE portal SET" +
 		" mxid=$1, name=$2, topic=$3, avatar=$4, avatar_url=$5, type=$6," +
-		" dmuser=$7, first_event_id=$8" +
-		" WHERE channel_id=$9 AND receiver=$10"
+		" dmuser=$7, first_event_id=$8, encrypted=$9" +
+		" WHERE channel_id=$10 AND receiver=$11"
 
 	_, err := p.db.Exec(query, p.mxidPtr(), p.Name, p.Topic, p.Avatar,
 		p.AvatarURL.String(), p.Type, p.DMUser, p.FirstEventID.String(),
+		p.Encrypted,
 		p.Key.ChannelID, p.Key.Receiver)
 
 	if err != nil {
diff --git a/database/portalquery.go b/database/portalquery.go
index 8b4353a..d9dd1ba 100644
--- a/database/portalquery.go
+++ b/database/portalquery.go
@@ -6,6 +6,12 @@ import (
 	"maunium.net/go/mautrix/id"
 )
 
+const (
+	portalSelect = "SELECT channel_id, receiver, mxid, name, topic, avatar," +
+		" avatar_url, type, dmuser, first_event_id, encrypted" +
+		" FROM portal"
+)
+
 type PortalQuery struct {
 	db  *Database
 	log log.Logger
@@ -19,23 +25,23 @@ func (pq *PortalQuery) New() *Portal {
 }
 
 func (pq *PortalQuery) GetAll() []*Portal {
-	return pq.getAll("SELECT * FROM portal")
+	return pq.getAll(portalSelect)
 }
 
 func (pq *PortalQuery) GetByID(key PortalKey) *Portal {
-	return pq.get("SELECT * FROM portal WHERE channel_id=$1 AND receiver=$2", key.ChannelID, key.Receiver)
+	return pq.get(portalSelect+" WHERE channel_id=$1 AND receiver=$2", key.ChannelID, key.Receiver)
 }
 
 func (pq *PortalQuery) GetByMXID(mxid id.RoomID) *Portal {
-	return pq.get("SELECT * FROM portal WHERE mxid=$1", mxid)
+	return pq.get(portalSelect+" WHERE mxid=$1", mxid)
 }
 
 func (pq *PortalQuery) GetAllByID(id string) []*Portal {
-	return pq.getAll("SELECT * FROM portal WHERE receiver=$1", id)
+	return pq.getAll(portalSelect+" WHERE receiver=$1", id)
 }
 
 func (pq *PortalQuery) FindPrivateChats(receiver string) []*Portal {
-	query := "SELECT * FROM portal WHERE receiver=$1 AND type=$2;"
+	query := portalSelect + " portal WHERE receiver=$1 AND type=$2;"
 
 	return pq.getAll(query, receiver, discordgo.ChannelTypeDM)
 }
diff --git a/database/sqlstatestore.go b/database/sqlstatestore.go
index c5d800b..e316773 100644
--- a/database/sqlstatestore.go
+++ b/database/sqlstatestore.go
@@ -272,3 +272,31 @@ func (s *SQLStateStore) HasPowerLevel(roomID id.RoomID, userID id.UserID, eventT
 
 	return s.GetPowerLevel(roomID, userID) >= s.GetPowerLevelRequirement(roomID, eventType)
 }
+
+func (store *SQLStateStore) FindSharedRooms(userID id.UserID) []id.RoomID {
+	query := "SELECT room_id FROM mx_user_profile" +
+		"LEFT JOIN portal ON portal.mxid=mx_user_profile.room_id" +
+		"WHERE user_id=$1 AND portal.encrypted=true"
+
+	rooms := []id.RoomID{}
+
+	rows, err := store.db.Query(query, userID)
+	if err != nil {
+		store.log.Warnfln("Failed to query shared rooms with %s: %v", userID, err)
+
+		return rooms
+	}
+
+	for rows.Next() {
+		var roomID id.RoomID
+
+		err = rows.Scan(&roomID)
+		if err != nil {
+			store.log.Warnfln("Failed to scan room ID: %v", err)
+		} else {
+			rooms = append(rooms, roomID)
+		}
+	}
+
+	return rooms
+}
diff --git a/go.mod b/go.mod
index bba6b6a..536f49d 100644
--- a/go.mod
+++ b/go.mod
@@ -20,6 +20,10 @@ require (
 	github.com/gorilla/mux v1.8.0 // indirect
 	github.com/pkg/errors v0.9.1 // indirect
 	github.com/russross/blackfriday/v2 v2.1.0 // indirect
+	github.com/tidwall/gjson v1.14.0 // indirect
+	github.com/tidwall/match v1.1.1 // indirect
+	github.com/tidwall/pretty v1.2.0 // indirect
+	github.com/tidwall/sjson v1.2.4 // indirect
 	golang.org/x/crypto v0.0.0-20220331220935-ae2d96664a29 // indirect
 	golang.org/x/net v0.0.0-20220403103023-749bd193bc2b // indirect
 	golang.org/x/sys v0.0.0-20220406163625-3f8b81556e12 // indirect
diff --git a/go.sum b/go.sum
index 2066e59..7ff3c7f 100644
--- a/go.sum
+++ b/go.sum
@@ -35,9 +35,13 @@ github.com/stretchr/testify v1.7.0/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/
 github.com/stretchr/testify v1.7.1 h1:5TQK59W5E3v0r2duFAb7P95B6hEeOyEnHRa8MjYSMTY=
 github.com/stretchr/testify v1.7.1/go.mod h1:6Fq8oRcR53rry900zMqJjRRixrwX3KX962/h/Wwjteg=
 github.com/tidwall/gjson v1.12.1/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/gjson v1.14.0 h1:6aeJ0bzojgWLa82gDQHcx3S0Lr/O51I9bJ5nv6JFx5w=
 github.com/tidwall/gjson v1.14.0/go.mod h1:/wbyibRr2FHMks5tjHJ5F8dMZh3AcwJEMf5vlfC0lxk=
+github.com/tidwall/match v1.1.1 h1:+Ho715JplO36QYgwN9PGYNhgZvoUSc9X2c80KVTi+GA=
 github.com/tidwall/match v1.1.1/go.mod h1:eRSPERbgtNPcGhD8UCthc6PmLEQXEWd3PRB5JTxsfmM=
+github.com/tidwall/pretty v1.2.0 h1:RWIZEg2iJ8/g6fDDYzMpobmaoGh5OLl4AXtGUGPcqCs=
 github.com/tidwall/pretty v1.2.0/go.mod h1:ITEVvHYasfjBbM0u2Pg8T2nJnzm8xPwvNhhsoaGGjNU=
+github.com/tidwall/sjson v1.2.4 h1:cuiLzLnaMeBhRmEv00Lpk3tkYrcxpmbU81tAY4Dw0tc=
 github.com/tidwall/sjson v1.2.4/go.mod h1:098SZ494YoMWPmMO6ct4dcFnqxwj9r/gF0Etp19pSNM=
 gitlab.com/beeper/discordgo v0.23.3-0.20220219094025-13ff4cc63da7 h1:8ieR27GadHnShqhsvPrDzL1/ZOntavGGt4TXqafncYE=
 gitlab.com/beeper/discordgo v0.23.3-0.20220219094025-13ff4cc63da7/go.mod h1:Hwfv4M8yP/MDh47BN+4Z1WItJ1umLKUyplCH5KcQPgE=