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feat(calls): end-to-end encrypted calls #6793

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c478178
feat(calls): add key exchange for end-to-end encrypted calls
AndyScherzinger Sep 30, 2026
da88aaf
feat(calls): encrypt calls through the MCU when the server requires it
AndyScherzinger Sep 30, 2026
3a8f540
chore(calls): allow early returns in the key exchange handlers
AndyScherzinger Oct 1, 2026
df07fc2
feat(calls): enable end-to-end encrypted calls with WebRTC 155 and vo…
rapterjet2004 Oct 8, 2026
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1 change: 1 addition & 0 deletions app/build.gradle.kts
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Original file line number Diff line number Diff line change
Expand Up @@ -338,6 +338,7 @@ dependencies {
implementation("com.github.nextcloud.android-common:ui:0.34.0")
implementation("com.github.nextcloud.android-common:core:0.34.0")
implementation("com.github.nextcloud-deps:android-talk-webrtc:155.8059.1")
implementation("com.github.nextcloud-releases:talk-clients-vodozemac:0.0.2")

"gplayImplementation"("com.google.android.gms:play-services-base:18.11.1")
"gplayImplementation"("com.google.firebase:firebase-messaging:26.0.0")
Expand Down
172 changes: 118 additions & 54 deletions app/src/main/java/com/nextcloud/talk/activities/CallActivity.kt
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Original file line number Diff line number Diff line change
Expand Up @@ -46,6 +46,7 @@ import androidx.activity.SystemBarStyle
import androidx.activity.enableEdgeToEdge
import androidx.activity.result.contract.ActivityResultContracts
import androidx.annotation.DrawableRes
import androidx.annotation.StringRes
import androidx.appcompat.app.AlertDialog
import androidx.compose.material3.MaterialTheme
import androidx.compose.runtime.LaunchedEffect
Expand Down Expand Up @@ -76,6 +77,8 @@ import com.nextcloud.talk.call.MediaConstraintsHelper
import com.nextcloud.talk.call.MessageSender
import com.nextcloud.talk.call.MessageSenderMcu
import com.nextcloud.talk.call.MessageSenderNoMcu
import com.nextcloud.talk.call.e2ee.CallEncryption
import com.nextcloud.talk.call.e2ee.FrameKeyRing
import com.nextcloud.talk.call.MutableLocalCallParticipantModel
import com.nextcloud.talk.call.ReactionAnimator
import com.nextcloud.talk.call.components.ParticipantGrid
Expand Down Expand Up @@ -322,6 +325,7 @@ class CallActivity : CallBaseActivity() {
private var roomJoinRefreshes = 0
private var hasMCU = false
private var hasExternalSignalingServer = false
private var isCallEndToEndEncryptionEnabled = false
private var conversationPassword: String? = null
private var powerManagerUtils: PowerManagerUtils? = null

Expand Down Expand Up @@ -524,10 +528,8 @@ class CallActivity : CallBaseActivity() {
return
}
processExtras(intent.extras!!)

if (warnAndFinishIfCallEndToEndEncryptionUnsupported()) {
return
}
isCallEndToEndEncryptionEnabled =
CapabilitiesUtil.isCallEndToEndEncryptionEnabled(conversationUser.capabilities?.spreedCapability)
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credentials = ApiUtils.getCredentials(conversationUser!!.username, conversationUser!!.token)
if (TextUtils.isEmpty(baseUrl)) {
Expand Down Expand Up @@ -570,15 +572,58 @@ class CallActivity : CallBaseActivity() {
checkInitialDevicePermissions()
}

private fun warnAndFinishIfCallEndToEndEncryptionUnsupported(): Boolean {
if (!CapabilitiesUtil.isCallEndToEndEncryptionEnabled(conversationUser?.capabilities?.spreedCapability)) {
/**
* Ends the call when it has to be end-to-end encrypted but can not be; media is never sent unencrypted instead.
*/
private fun failCallEncryption(@StringRes reason: Int) {
if (currentCallStatus === CallStatus.LEAVING) {
return
}
Log.e(TAG, "Ending call: ${context.getString(reason)}")
runOnUiThread { Toast.makeText(context, reason, Toast.LENGTH_LONG).show() }
hangup(shutDownView = true, endCallForAll = false)
}

/**
* The key exchange of the call, null when calls are not end-to-end encrypted or it is not set up yet.
*/
private fun callEncryption(): CallEncryption? =
if (isCallEndToEndEncryptionEnabled) webSocketClient?.callEncryption else null

// Encrypted calls only work through the MCU, which is the only place with a key exchange
private fun ensureMcuForCallEncryption(): Boolean {
if (isCallEndToEndEncryptionEnabled && !hasMCU) {
failCallEncryption(R.string.nc_call_e2ee_requires_hpb)
return false
}
return true
}

// The key exchange is created when the room is joined, so it has to exist before publishing
private fun ensureCallEncryption(): Boolean {
if (isCallEndToEndEncryptionEnabled && callEncryption() == null) {
failCallEncryption(R.string.nc_call_e2ee_setup_failed)
return false
}
Toast.makeText(context, R.string.nc_call_e2ee_not_supported, Toast.LENGTH_LONG).show()
finish()
return true
}

private fun createMessageSender(): MessageSender =
if (hasMCU) {
MessageSenderMcu(
signalingMessageSender,
getParticipantSessionKeys(),
peerConnectionWrapperList,
webSocketClient!!.sessionId
)
} else {
MessageSenderNoMcu(
signalingMessageSender,
getParticipantSessionKeys(),
peerConnectionWrapperList
)
}

private fun initCallRecordingViewModel(recordingState: Int) {
callRecordingViewModel = ViewModelProvider(this, viewModelFactory).get(
CallRecordingViewModel::class.java
Expand Down Expand Up @@ -1717,8 +1762,16 @@ class CallActivity : CallBaseActivity() {

override fun onNext(capabilitiesOverall: CapabilitiesOverall) {
// FIXME check for compatible Call API version
// The policy comes from these fresh capabilities, not from the cached ones of the user
capabilitiesOverall.ocs?.data?.capabilities?.let {
conversationUser.capabilities = it
isCallEndToEndEncryptionEnabled =
CapabilitiesUtil.isCallEndToEndEncryptionEnabled(it.spreedCapability)
}
if (hasExternalSignalingServer) {
setupAndInitiateWebSocketsConnection()
} else if (isCallEndToEndEncryptionEnabled) {
failCallEncryption(R.string.nc_call_e2ee_requires_hpb)
} else {
signalingMessageReceiver = internalSignalingMessageReceiver
signalingMessageReceiver!!.addListener(localParticipantMessageListener)
Expand Down Expand Up @@ -2060,25 +2113,16 @@ class CallActivity : CallBaseActivity() {
hasMCU = webSocketClient!!.hasMCU()
Log.d(TAG, "hasMCU is $hasMCU")

if (hasMCU) {
messageSender = MessageSenderMcu(
signalingMessageSender,
getParticipantSessionKeys(),
peerConnectionWrapperList,
webSocketClient!!.sessionId
)
} else {
messageSender = MessageSenderNoMcu(
signalingMessageSender,
getParticipantSessionKeys(),
peerConnectionWrapperList
)
}
messageSender = createMessageSender()
Comment thread
AndyScherzinger marked this conversation as resolved.
} else {
if (webSocketClient!!.isConnected && currentCallStatus === CallStatus.PUBLISHER_FAILED) {
webSocketClient!!.restartWebSocket()
}
}
// An already connected signaling server sends no new "hello", so the MCU requirement is checked here
if (webSocketClient!!.isConnected && !ensureMcuForCallEncryption()) {
return
}
joinRoomAndCall()
}

Expand All @@ -2104,21 +2148,12 @@ class CallActivity : CallBaseActivity() {
hasMCU = webSocketClient!!.hasMCU()
Log.d(TAG, "hasMCU is $hasMCU")

if (hasMCU) {
messageSender = MessageSenderMcu(
signalingMessageSender,
getParticipantSessionKeys(),
peerConnectionWrapperList,
webSocketClient!!.sessionId
)
} else {
messageSender = MessageSenderNoMcu(
signalingMessageSender,
getParticipantSessionKeys(),
peerConnectionWrapperList
)
if (!ensureMcuForCallEncryption()) {
return
}

messageSender = createMessageSender()

if (!webSocketCommunicationEvent.getHashMap()!!.containsKey("oldResumeId")) {
if (currentCallStatus === CallStatus.RECONNECTING) {
hangup(false, false)
Expand Down Expand Up @@ -2501,7 +2536,7 @@ class CallActivity : CallBaseActivity() {
removeSessions(participantsInCall)
return
}
if (currentCallStatus === CallStatus.LEAVING) {
if (currentCallStatus === CallStatus.LEAVING || (hasMCU && !ensureCallEncryption())) {
return
}
if (hasMCU) {
Expand Down Expand Up @@ -2537,6 +2572,9 @@ class CallActivity : CallBaseActivity() {
var selfJoined = false
val selfParticipantHasAudioOrVideo = participantInCallFlagsHaveAudioOrVideo(selfParticipant)
for (participant in joined) {
if (currentCallStatus === CallStatus.LEAVING) {
return
}
val sessionId = participant.sessionId
if (sessionId == null) {
Log.w(TAG, "Null sessionId for call participant, this should not happen: $participant")
Expand Down Expand Up @@ -2653,6 +2691,7 @@ class CallActivity : CallBaseActivity() {
return null
}
peerConnectionWrapper = createPeerConnectionWrapperForSessionIdAndType(publisher, sessionId, type)
?: return null
synchronized(remoteAudioPlayoutLock) {
peerConnectionWrapperList.add(peerConnectionWrapper)
peerConnectionWrapper.setRemoteAudioPlayoutEnabled(remoteAudioPlayoutEnabled)
Expand Down Expand Up @@ -2680,7 +2719,7 @@ class CallActivity : CallBaseActivity() {
publisher: Boolean,
sessionId: String?,
type: String
): PeerConnectionWrapper {
): PeerConnectionWrapper? {
fun getPeerConnectionFactory(type: String): PeerConnectionFactory? {
fun initScreenSharePeerConnectionFactory(): PeerConnectionFactory? {
val options = PeerConnectionFactory.Options()
Expand Down Expand Up @@ -2739,23 +2778,48 @@ class CallActivity : CallBaseActivity() {
}
}

return PeerConnectionWrapper(
tempPeerConnectionFactory,
iceServers,
tempSdpConstraints,
sessionId,
// #6169: the remote sessionId is a signaling-layer session ID when external signaling
// is used, so the offerer election must compare same-namespace IDs. Pass the local
// signaling session (matching the currentSessionId resolution used elsewhere); with
// internal signaling webSocketClient == null, so callSession is used as before.
if (webSocketClient != null) webSocketClient!!.sessionId else callSession,
tempLocalStream,
tempIsMCUPublisher,
tempHasMCU,
type,
signalingMessageReceiver,
signalingMessageSender
)
val (senderKeyRing, receiverKeyRing) = keyRingsFor(tempIsMCUPublisher, tempHasMCU, sessionId)

return try {
PeerConnectionWrapper(
tempPeerConnectionFactory,
iceServers,
tempSdpConstraints,
sessionId,
// #6169: the remote sessionId is a signaling-layer session ID when external signaling
// is used, so the offerer election must compare same-namespace IDs. Pass the local
// signaling session (matching the currentSessionId resolution used elsewhere); with
// internal signaling webSocketClient == null, so callSession is used as before.
if (webSocketClient != null) webSocketClient!!.sessionId else callSession,
tempLocalStream,
tempIsMCUPublisher,
tempHasMCU,
type,
signalingMessageReceiver,
signalingMessageSender,
isCallEndToEndEncryptionEnabled,
senderKeyRing,
receiverKeyRing
)
} catch (e: IllegalStateException) {
Log.e(TAG, "Not creating a connection to $sessionId", e)
failCallEncryption(R.string.nc_call_e2ee_setup_failed)
null
}
}

// The key exchange only exists with the MCU: own keys go to the publisher, the remote keys to each subscriber.
private fun keyRingsFor(
isMCUPublisher: Boolean,
hasMCU: Boolean,
sessionId: String?
): Pair<FrameKeyRing?, FrameKeyRing?> {
val callEncryption = callEncryption() ?: return null to null
return when {
isMCUPublisher -> callEncryption.ownKeyRing to null
hasMCU && sessionId != null -> null to callEncryption.keyRing(sessionId)
else -> null to null
}
}

private fun addCallParticipant(sessionId: String?) {
Expand Down
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