Use workers to send verification messages

matrix-sdk-android/build.gradle

@@ -106,6 +106,7 @@ dependencies {
 
     implementation "androidx.lifecycle:lifecycle-extensions:$lifecycle_version"
     kapt "androidx.lifecycle:lifecycle-compiler:$lifecycle_version"
+    implementation("com.google.guava:guava:28.2-jre")
 
     // Network
     implementation 'com.squareup.retrofit2:retrofit:2.6.2'

matrix-sdk-android/src/main/java/im/vector/matrix/android/api/session/crypto/sas/SasVerificationService.kt

@@ -55,7 +55,7 @@ interface SasVerificationService {
      */
     fun beginKeyVerification(method: String, userId: String, deviceID: String): String?
 
-    fun requestKeyVerificationInDMs(userId: String, roomId: String, callback: MatrixCallback<String>?): PendingVerificationRequest
+    fun requestKeyVerificationInDMs(userId: String, roomId: String): PendingVerificationRequest
 
     fun beginKeyVerificationInDMs(method: String,
                                   transactionId: String,

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/CryptoModule.kt

@@ -180,6 +180,9 @@ internal abstract class CryptoModule {
     @Binds
     abstract fun bindEncryptEventTask(encryptEventTask: DefaultEncryptEventTask): EncryptEventTask
 
+    @Binds
+    abstract fun bindSendVerificationMessageTask(sendDefaultSendVerificationMessageTask: DefaultSendVerificationMessageTask): SendVerificationMessageTask
+
     @Binds
     abstract fun bindClaimOneTimeKeysForUsersDeviceTask(claimOneTimeKeysForUsersDevice: DefaultClaimOneTimeKeysForUsersDevice)
             : ClaimOneTimeKeysForUsersDeviceTask

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/tasks/RequestVerificationDMTask.kt

@@ -1,95 +0,0 @@
-/*
- * Copyright 2019 New Vector Ltd
- *
- * Licensed under the Apache License, Version 2.0 (the "License");
- * you may not use this file except in compliance with the License.
- * You may obtain a copy of the License at
- *
- * http://www.apache.org/licenses/LICENSE-2.0
- *
- * Unless required by applicable law or agreed to in writing, software
- * distributed under the License is distributed on an "AS IS" BASIS,
- * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
- * See the License for the specific language governing permissions and
- * limitations under the License.
- */
-package im.vector.matrix.android.internal.crypto.tasks
-
-import com.zhuinden.monarchy.Monarchy
-import im.vector.matrix.android.api.session.crypto.CryptoService
-import im.vector.matrix.android.api.session.events.model.Event
-import im.vector.matrix.android.api.session.room.send.SendState
-import im.vector.matrix.android.internal.network.executeRequest
-import im.vector.matrix.android.internal.session.room.RoomAPI
-import im.vector.matrix.android.internal.session.room.send.LocalEchoEventFactory
-import im.vector.matrix.android.internal.session.room.send.LocalEchoUpdater
-import im.vector.matrix.android.internal.session.room.send.SendResponse
-import im.vector.matrix.android.internal.task.Task
-import javax.inject.Inject
-
-internal interface RequestVerificationDMTask : Task<RequestVerificationDMTask.Params, SendResponse> {
-    data class Params(
-            val event: Event,
-            val cryptoService: CryptoService
-    )
-
-    fun createParamsAndLocalEcho(roomId: String, from: String, methods: List<String>, to: String, cryptoService: CryptoService): Params
-}
-
-internal class DefaultRequestVerificationDMTask @Inject constructor(
-        private val localEchoUpdater: LocalEchoUpdater,
-        private val localEchoEventFactory: LocalEchoEventFactory,
-        private val encryptEventTask: DefaultEncryptEventTask,
-        private val monarchy: Monarchy,
-        private val roomAPI: RoomAPI)
-    : RequestVerificationDMTask {
-
-    override fun createParamsAndLocalEcho(roomId: String, from: String, methods: List<String>, to: String, cryptoService: CryptoService)
-            : RequestVerificationDMTask.Params {
-        val event = localEchoEventFactory.createVerificationRequest(roomId, from, to, methods)
-                .also { localEchoEventFactory.saveLocalEcho(monarchy, it) }
-        return RequestVerificationDMTask.Params(
-                event,
-                cryptoService
-        )
-    }
-
-    override suspend fun execute(params: RequestVerificationDMTask.Params): SendResponse {
-        val event = handleEncryption(params)
-        val localID = event.eventId!!
-
-        try {
-            localEchoUpdater.updateSendState(localID, SendState.SENDING)
-            val executeRequest = executeRequest<SendResponse> {
-                apiCall = roomAPI.send(
-                        localID,
-                        roomId = event.roomId ?: "",
-                        content = event.content,
-                        eventType = event.type // message or room.encrypted
-                )
-            }
-            localEchoUpdater.updateSendState(localID, SendState.SENT)
-            return executeRequest
-        } catch (e: Throwable) {
-            localEchoUpdater.updateSendState(localID, SendState.UNDELIVERED)
-            throw e
-        }
-    }
-
-    private suspend fun handleEncryption(params: RequestVerificationDMTask.Params): Event {
-        val roomId = params.event.roomId ?: ""
-        if (params.cryptoService.isRoomEncrypted(roomId)) {
-            try {
-                return encryptEventTask.execute(EncryptEventTask.Params(
-                        roomId,
-                        params.event,
-                        listOf("m.relates_to"),
-                        params.cryptoService
-                ))
-            } catch (throwable: Throwable) {
-                // We said it's ok to send verification request in clear
-            }
-        }
-        return params.event
-    }
-}

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/tasks/SendVerificationMessageTask.kt

@@ -15,64 +15,29 @@
  */
 package im.vector.matrix.android.internal.crypto.tasks
 
-import com.zhuinden.monarchy.Monarchy
 import im.vector.matrix.android.api.session.crypto.CryptoService
-import im.vector.matrix.android.api.session.events.model.Content
 import im.vector.matrix.android.api.session.events.model.Event
-import im.vector.matrix.android.api.session.events.model.LocalEcho
-import im.vector.matrix.android.api.session.events.model.UnsignedData
 import im.vector.matrix.android.api.session.room.send.SendState
-import im.vector.matrix.android.internal.di.UserId
 import im.vector.matrix.android.internal.network.executeRequest
 import im.vector.matrix.android.internal.session.room.RoomAPI
-import im.vector.matrix.android.internal.session.room.send.LocalEchoEventFactory
 import im.vector.matrix.android.internal.session.room.send.LocalEchoUpdater
 import im.vector.matrix.android.internal.session.room.send.SendResponse
 import im.vector.matrix.android.internal.task.Task
 import javax.inject.Inject
 
-internal interface SendVerificationMessageTask : Task<SendVerificationMessageTask.Params, SendResponse> {
+internal interface SendVerificationMessageTask : Task<SendVerificationMessageTask.Params, String> {
     data class Params(
-            val type: String,
             val event: Event,
             val cryptoService: CryptoService?
     )
-
-    fun createParamsAndLocalEcho(type: String,
-                                 roomId: String,
-                                 content: Content,
-                                 cryptoService: CryptoService?) : Params
 }
 
 internal class DefaultSendVerificationMessageTask @Inject constructor(
         private val localEchoUpdater: LocalEchoUpdater,
-        private val localEchoEventFactory: LocalEchoEventFactory,
         private val encryptEventTask: DefaultEncryptEventTask,
-        private val monarchy: Monarchy,
-        @UserId private val userId: String,
         private val roomAPI: RoomAPI) : SendVerificationMessageTask {
 
-    override fun createParamsAndLocalEcho(type: String, roomId: String, content: Content, cryptoService: CryptoService?): SendVerificationMessageTask.Params {
-        val localID = LocalEcho.createLocalEchoId()
-        val event = Event(
-                roomId = roomId,
-                originServerTs = System.currentTimeMillis(),
-                senderId = userId,
-                eventId = localID,
-                type = type,
-                content = content,
-                unsignedData = UnsignedData(age = null, transactionId = localID)
-        ).also {
-            localEchoEventFactory.saveLocalEcho(monarchy, it)
-        }
-        return SendVerificationMessageTask.Params(
-                type,
-                event,
-                cryptoService
-        )
-    }
-
-    override suspend fun execute(params: SendVerificationMessageTask.Params): SendResponse {
+    override suspend fun execute(params: SendVerificationMessageTask.Params): String {
         val event = handleEncryption(params)
         val localID = event.eventId!!
 
@@ -87,7 +52,7 @@ internal class DefaultSendVerificationMessageTask @Inject constructor(
                 )
             }
             localEchoUpdater.updateSendState(localID, SendState.SENT)
-            return executeRequest
+            return executeRequest.eventId
         } catch (e: Throwable) {
             localEchoUpdater.updateSendState(localID, SendState.UNDELIVERED)
             throw e

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/DefaultSasVerificationService.kt

@@ -16,6 +16,7 @@
 
 package im.vector.matrix.android.internal.crypto.verification
 
+import android.content.Context
 import android.os.Handler
 import android.os.Looper
 import dagger.Lazy
@@ -28,6 +29,7 @@ import im.vector.matrix.android.api.session.crypto.sas.SasVerificationTxState
 import im.vector.matrix.android.api.session.crypto.sas.safeValueOf
 import im.vector.matrix.android.api.session.events.model.Event
 import im.vector.matrix.android.api.session.events.model.EventType
+import im.vector.matrix.android.api.session.events.model.LocalEcho
 import im.vector.matrix.android.api.session.events.model.toModel
 import im.vector.matrix.android.api.session.room.model.message.*
 import im.vector.matrix.android.internal.crypto.DeviceListManager
@@ -37,12 +39,7 @@ import im.vector.matrix.android.internal.crypto.model.MXDeviceInfo
 import im.vector.matrix.android.internal.crypto.model.MXUsersDevicesMap
 import im.vector.matrix.android.internal.crypto.model.rest.*
 import im.vector.matrix.android.internal.crypto.store.IMXCryptoStore
-import im.vector.matrix.android.internal.crypto.tasks.DefaultRequestVerificationDMTask
 import im.vector.matrix.android.internal.session.SessionScope
-import im.vector.matrix.android.internal.session.room.send.SendResponse
-import im.vector.matrix.android.internal.task.TaskConstraints
-import im.vector.matrix.android.internal.task.TaskExecutor
-import im.vector.matrix.android.internal.task.configureWith
 import im.vector.matrix.android.internal.util.MatrixCoroutineDispatchers
 import kotlinx.coroutines.GlobalScope
 import kotlinx.coroutines.launch
@@ -55,16 +52,15 @@ import kotlin.collections.set
 
 @SessionScope
 internal class DefaultSasVerificationService @Inject constructor(
+        private val context: Context,
         private val credentials: Credentials,
         private val cryptoStore: IMXCryptoStore,
         private val myDeviceInfoHolder: Lazy<MyDeviceInfoHolder>,
         private val deviceListManager: DeviceListManager,
         private val setDeviceVerificationAction: SetDeviceVerificationAction,
-        private val requestVerificationDMTask: DefaultRequestVerificationDMTask,
         private val coroutineDispatchers: MatrixCoroutineDispatchers,
         private val sasTransportRoomMessageFactory: SasTransportRoomMessageFactory,
-        private val sasTransportToDeviceFactory: SasTransportToDeviceFactory,
-        private val taskExecutor: TaskExecutor
+        private val sasTransportToDeviceFactory: SasTransportToDeviceFactory
 ) : VerificationTransaction.Listener, SasVerificationService {
 
     private val uiHandler = Handler(Looper.getMainLooper())
@@ -279,8 +275,9 @@ internal class DefaultSasVerificationService @Inject constructor(
         if (startReq?.isValid()?.not() == true) {
             Timber.e("## received invalid verification request")
             if (startReq.transactionID != null) {
-                sasTransportRoomMessageFactory.createTransport(event.roomId
-                        ?: "", cryptoService, null).cancelTransaction(
+                sasTransportRoomMessageFactory.createTransport(context, credentials.userId, credentials.deviceId
+                        ?: "", event.roomId
+                        ?: "", null).cancelTransaction(
                         startReq.transactionID ?: "",
                         otherUserId!!,
                         startReq.fromDevice ?: event.getSenderKey()!!,
@@ -291,11 +288,13 @@ internal class DefaultSasVerificationService @Inject constructor(
         }
 
         handleStart(otherUserId, startReq as VerificationInfoStart) {
-            it.transport = sasTransportRoomMessageFactory.createTransport(event.roomId
-                    ?: "", cryptoService, it)
+            it.transport = sasTransportRoomMessageFactory.createTransport(context, credentials.userId, credentials.deviceId
+                    ?: "", event.roomId
+                    ?: "", it)
         }?.let {
-            sasTransportRoomMessageFactory.createTransport(event.roomId
-                    ?: "", cryptoService, null).cancelTransaction(
+            sasTransportRoomMessageFactory.createTransport(context, credentials.userId, credentials.deviceId
+                    ?: "", event.roomId
+                    ?: "", null).cancelTransaction(
                     startReq.transactionID ?: "",
                     otherUserId!!,
                     startReq.fromDevice ?: event.getSenderKey()!!,
@@ -693,57 +692,37 @@ internal class DefaultSasVerificationService @Inject constructor(
         }
     }
 
-    override fun requestKeyVerificationInDMs(userId: String, roomId: String, callback: MatrixCallback<String>?)
+    override fun requestKeyVerificationInDMs(userId: String, roomId: String)
             : PendingVerificationRequest {
         Timber.i("## SAS Requesting verification to user: $userId in room $roomId")
+
         val requestsForUser = pendingRequests[userId]
                 ?: ArrayList<PendingVerificationRequest>().also {
                     pendingRequests[userId] = it
                 }
 
-        val params = requestVerificationDMTask.createParamsAndLocalEcho(
-                roomId = roomId,
-                from = credentials.deviceId ?: "",
-                methods = listOf(KeyVerificationStart.VERIF_METHOD_SAS),
-                to = userId,
-                cryptoService = cryptoService
-        )
+        val transport = sasTransportRoomMessageFactory.createTransport(context, credentials.userId, credentials.deviceId
+                ?: "", roomId, null)
+
+        val localID = LocalEcho.createLocalEchoId()
+
         val verificationRequest = PendingVerificationRequest(
                 ageLocalTs = System.currentTimeMillis(),
                 isIncoming = false,
-                localID = params.event.eventId ?: "",
+                localID = localID,
                 otherUserId = userId
         )
-        requestsForUser.add(verificationRequest)
-        dispatchRequestAdded(verificationRequest)
 
-        requestVerificationDMTask.configureWith(
-                requestVerificationDMTask.createParamsAndLocalEcho(
-                        roomId = roomId,
-                        from = credentials.deviceId ?: "",
-                        methods = listOf(KeyVerificationStart.VERIF_METHOD_SAS),
-                        to = userId,
-                        cryptoService = cryptoService
-                )
-        ) {
-            this.callback = object : MatrixCallback<SendResponse> {
-                override fun onSuccess(data: SendResponse) {
-                    params.event.getClearContent().toModel<MessageVerificationRequestContent>()?.let {
+        transport.sendVerificationRequest(localID, userId, roomId) { syncedId, info ->
+            // We need to update with the syncedID
             updatePendingRequest(verificationRequest.copy(
-                                transactionId = data.eventId,
-                                requestInfo = it
+                    transactionId = syncedId,
+                    requestInfo = info
             ))
         }
-                    callback?.onSuccess(data.eventId)
-                }
 
-                override fun onFailure(failure: Throwable) {
-                    callback?.onFailure(failure)
-                }
-            }
-            constraints = TaskConstraints(true)
-            retryCount = 3
-        }.executeBy(taskExecutor)
+        requestsForUser.add(verificationRequest)
+        dispatchRequestAdded(verificationRequest)
 
         return verificationRequest
     }
@@ -776,7 +755,8 @@ internal class DefaultSasVerificationService @Inject constructor(
                     transactionId,
                     otherUserId,
                     otherDeviceId)
-            tx.transport = sasTransportRoomMessageFactory.createTransport(roomId, cryptoService, tx)
+            tx.transport = sasTransportRoomMessageFactory.createTransport(context, credentials.userId, credentials.deviceId
+                    ?: "", roomId, tx)
             addTransaction(tx)
 
             tx.start()
@@ -790,7 +770,8 @@ internal class DefaultSasVerificationService @Inject constructor(
         // Let's find the related request
         getExistingVerificationRequest(otherUserId)?.find { it.transactionId == transactionId }?.let {
             // we need to send a ready event, with matching methods
-            val transport = sasTransportRoomMessageFactory.createTransport(roomId, cryptoService, null)
+            val transport = sasTransportRoomMessageFactory.createTransport(context, credentials.userId, credentials.deviceId
+                    ?: "", roomId, null)
             val methods = it.requestInfo?.methods?.intersect(listOf(KeyVerificationStart.VERIF_METHOD_SAS))?.toList()
             if (methods.isNullOrEmpty()) {
                 Timber.i("Cannot ready this request, no common methods found txId:$transactionId")
@@ -831,28 +812,4 @@ internal class DefaultSasVerificationService @Inject constructor(
             this.removeTransaction(tx.otherUserId, tx.transactionId)
         }
     }
-//
-//    fun cancelTransaction(transactionId: String, userId: String, userDevice: String, code: CancelCode, roomId: String? = null) {
-//        val cancelMessage = KeyVerificationCancel.create(transactionId, code)
-//        val contentMap = MXUsersDevicesMap<Any>()
-//        contentMap.setObject(userId, userDevice, cancelMessage)
-//
-//        if (roomId != null) {
-//
-//        } else {
-//            sendToDeviceTask
-//                    .configureWith(SendToDeviceTask.Params(EventType.KEY_VERIFICATION_CANCEL, contentMap, transactionId)) {
-//                        this.callback = object : MatrixCallback<Unit> {
-//                            override fun onSuccess(data: Unit) {
-//                                Timber.v("## SAS verification [$transactionId] canceled for reason ${code.value}")
-//                            }
-//
-//                            override fun onFailure(failure: Throwable) {
-//                                Timber.e(failure, "## SAS verification [$transactionId] failed to cancel.")
-//                            }
-//                        }
-//                    }
-//                    .executeBy(taskExecutor)
-//        }
-//    }
 }

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/SasTransport.kt

@@ -17,6 +17,7 @@ package im.vector.matrix.android.internal.crypto.verification
 
 import im.vector.matrix.android.api.session.crypto.sas.CancelCode
 import im.vector.matrix.android.api.session.crypto.sas.SasVerificationTxState
+import im.vector.matrix.android.api.session.room.model.message.MessageVerificationRequestContent
 
 /**
  * SAS verification can be performed using toDevice events or via DM.
@@ -33,6 +34,8 @@ internal interface SasTransport {
                     onErrorReason: CancelCode,
                     onDone: (() -> Unit)?)
 
+    fun sendVerificationRequest(localID: String, otherUserId: String, roomId: String, callback: (String?, MessageVerificationRequestContent?) -> Unit)
+
     fun cancelTransaction(transactionId: String, userId: String, userDevice: String, code: CancelCode)
 
     fun done(transactionId: String)

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/SasTransportRoomMessage.kt

@@ -15,33 +15,41 @@
  */
 package im.vector.matrix.android.internal.crypto.verification
 
-import im.vector.matrix.android.api.MatrixCallback
-import im.vector.matrix.android.api.session.crypto.CryptoService
+import android.content.Context
+import androidx.lifecycle.Observer
+import androidx.work.*
+import com.zhuinden.monarchy.Monarchy
+import im.vector.matrix.android.R
 import im.vector.matrix.android.api.session.crypto.sas.CancelCode
 import im.vector.matrix.android.api.session.crypto.sas.SasVerificationTxState
-import im.vector.matrix.android.api.session.events.model.EventType
-import im.vector.matrix.android.api.session.events.model.RelationType
-import im.vector.matrix.android.api.session.events.model.toContent
+import im.vector.matrix.android.api.session.events.model.*
 import im.vector.matrix.android.api.session.room.model.message.*
 import im.vector.matrix.android.api.session.room.model.relation.RelationDefaultContent
-import im.vector.matrix.android.internal.crypto.tasks.DefaultSendVerificationMessageTask
-import im.vector.matrix.android.internal.crypto.tasks.SendVerificationMessageTask
-import im.vector.matrix.android.internal.session.room.send.SendResponse
-import im.vector.matrix.android.internal.task.TaskConstraints
-import im.vector.matrix.android.internal.task.TaskExecutor
-import im.vector.matrix.android.internal.task.TaskThread
-import im.vector.matrix.android.internal.task.configureWith
+import im.vector.matrix.android.internal.crypto.model.rest.KeyVerificationStart
+import im.vector.matrix.android.internal.session.room.send.LocalEchoEventFactory
+import im.vector.matrix.android.internal.worker.WorkManagerUtil
+import im.vector.matrix.android.internal.worker.WorkerParamsFactory
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.launch
 import timber.log.Timber
+import java.util.*
+import java.util.concurrent.Executors
+import java.util.concurrent.TimeUnit
 import javax.inject.Inject
 
 internal class SasTransportRoomMessage(
+        private val context: Context,
+        private val userId: String,
+        private val userDevice: String,
         private val roomId: String,
-        private val cryptoService: CryptoService,
-        private val tx: SASVerificationTransaction?,
-        private val sendVerificationMessageTask: SendVerificationMessageTask,
-        private val taskExecutor: TaskExecutor
+        private val monarchy: Monarchy,
+        private val localEchoEventFactory: LocalEchoEventFactory,
+        private val tx: SASVerificationTransaction?
 ) : SasTransport {
 
+    private val listenerExecutor = Executors.newSingleThreadExecutor()
+
     override fun sendToOther(type: String,
                              verificationInfo: VerificationInfo,
                              nextState: SasVerificationTxState,
@@ -49,83 +57,167 @@ internal class SasTransportRoomMessage(
                              onDone: (() -> Unit)?) {
         Timber.d("## SAS sending msg type $type")
         Timber.v("## SAS sending msg info $verificationInfo")
-        sendVerificationMessageTask.configureWith(
-                sendVerificationMessageTask.createParamsAndLocalEcho(
-                        type,
-                        roomId,
-                        verificationInfo.toEventContent()!!,
-                        cryptoService
+        val event = createEventAndLocalEcho(
+                type = type,
+                roomId = roomId,
+                content = verificationInfo.toEventContent()!!
         )
-        ) {
-            callbackThread = TaskThread.DM_VERIF
-            executionThread = TaskThread.DM_VERIF
-            constraints = TaskConstraints(true)
-            callback = object : MatrixCallback<SendResponse> {
-                override fun onSuccess(data: SendResponse) {
+
+        val workerParams = WorkerParamsFactory.toData(SendVerificationMessageWorker.Params(
+                userId = userId,
+                event = event
+        ))
+        val enqueueInfo = enqueueSendWork(workerParams)
+
+        // I cannot just listen to the given work request, because when used in a uniqueWork,
+        // The callback is called while it is still Running ...
+
+//        Futures.addCallback(enqueueInfo.first.result, object : FutureCallback<Operation.State.SUCCESS> {
+//            override fun onSuccess(result: Operation.State.SUCCESS?) {
+//                if (onDone != null) {
+//                    onDone()
+//                } else {
+//                    tx?.state = nextState
+//                }
+//            }
+//
+//            override fun onFailure(t: Throwable) {
+//                Timber.e("## SAS verification [${tx?.transactionId}] failed to send toDevice in state : ${tx?.state}, reason: ${t.localizedMessage}")
+//                tx?.cancel(onErrorReason)
+//            }
+//        }, listenerExecutor)
+
+        val workLiveData = WorkManager.getInstance(context).getWorkInfosForUniqueWorkLiveData("${roomId}_VerificationWork")
+
+        val observer = object : Observer<List<WorkInfo>> {
+            override fun onChanged(workInfoList: List<WorkInfo>?) {
+                workInfoList
+                        ?.filter { it.state == WorkInfo.State.SUCCEEDED }
+                        ?.firstOrNull { it.id == enqueueInfo.second }
+                        ?.let { wInfo ->
+                            if (wInfo.outputData.getBoolean("failed", false)) {
+                                Timber.e("## SAS verification [${tx?.transactionId}] failed to send verification message in state : ${tx?.state}")
+                                tx?.cancel(onErrorReason)
+                            } else {
                                 if (onDone != null) {
                                     onDone()
                                 } else {
                                     tx?.state = nextState
                                 }
                             }
+                            workLiveData.removeObserver(this)
+                        }
+            }
+        }
 
-                override fun onFailure(failure: Throwable) {
-                    Timber.e("## SAS verification [${tx?.transactionId}] failed to send toDevice in state : ${tx?.state}")
-                    tx?.cancel(onErrorReason)
+        // TODO listen to DB to get synced info
+        GlobalScope.launch(Dispatchers.Main) {
+            workLiveData.observeForever(observer)
+        }
+
+    }
+
+    override fun sendVerificationRequest(localID: String, otherUserId: String, roomId: String, callback: (String?, MessageVerificationRequestContent?) -> Unit) {
+        val info = MessageVerificationRequestContent(
+                body = context.getString(R.string.key_verification_request_fallback_message, userId),
+                fromDevice = userDevice,
+                toUserId = otherUserId,
+                methods = listOf(KeyVerificationStart.VERIF_METHOD_SAS)
+        )
+        val content = info.toContent()
+
+        val event = createEventAndLocalEcho(
+                localID,
+                EventType.MESSAGE,
+                roomId,
+                content
+        )
+
+        val workerParams = WorkerParamsFactory.toData(SendVerificationMessageWorker.Params(
+                userId = userId,
+                event = event
+        ))
+
+        val workRequest = WorkManagerUtil.matrixOneTimeWorkRequestBuilder<SendVerificationMessageWorker>()
+                .setConstraints(WorkManagerUtil.workConstraints)
+                .setInputData(workerParams)
+                .setBackoffCriteria(BackoffPolicy.LINEAR, 2_000L, TimeUnit.MILLISECONDS)
+                .build()
+
+        WorkManager.getInstance(context)
+                .beginUniqueWork("${roomId}_VerificationWork", ExistingWorkPolicy.APPEND, workRequest)
+                .enqueue()
+
+        // I cannot just listen to the given work request, because when used in a uniqueWork,
+        // The callback is called while it is still Running ...
+
+        val workLiveData = WorkManager.getInstance(context).getWorkInfosForUniqueWorkLiveData("${roomId}_VerificationWork")
+
+        val observer = object : Observer<List<WorkInfo>> {
+            override fun onChanged(workInfoList: List<WorkInfo>?) {
+                workInfoList
+                        ?.filter { it.state == WorkInfo.State.SUCCEEDED }
+                        ?.firstOrNull { it.id == workRequest.id }
+                        ?.let { wInfo ->
+                            if (wInfo.outputData.getBoolean("failed", false)) {
+                                callback(null, null)
+                            } else if (wInfo.outputData.getString(localID) != null) {
+                                callback(wInfo.outputData.getString(localID), info)
+                            } else {
+                                callback(null, null)
+                            }
+                            workLiveData.removeObserver(this)
                         }
             }
-            retryCount = 3
         }
-                .executeBy(taskExecutor)
+
+        // TODO listen to DB to get synced info
+        GlobalScope.launch(Dispatchers.Main) {
+            workLiveData.observeForever(observer)
+        }
     }
 
     override fun cancelTransaction(transactionId: String, userId: String, userDevice: String, code: CancelCode) {
         Timber.d("## SAS canceling transaction $transactionId for reason $code")
-        sendVerificationMessageTask.configureWith(
-                sendVerificationMessageTask.createParamsAndLocalEcho(
-                        EventType.KEY_VERIFICATION_CANCEL,
-                        roomId,
-                        MessageVerificationCancelContent.create(transactionId, code).toContent(),
-                        cryptoService
+        val event = createEventAndLocalEcho(
+                type = EventType.KEY_VERIFICATION_CANCEL,
+                roomId = roomId,
+                content = MessageVerificationCancelContent.create(transactionId, code).toContent()
         )
-        ) {
-            callbackThread = TaskThread.DM_VERIF
-            executionThread = TaskThread.DM_VERIF
-            constraints = TaskConstraints(true)
-            retryCount = 3
-            callback = object : MatrixCallback<SendResponse> {
-                override fun onSuccess(data: SendResponse) {
-                    Timber.v("## SAS verification [$transactionId] canceled for reason ${code.value}")
-                }
-
-                override fun onFailure(failure: Throwable) {
-                    Timber.e(failure, "## SAS verification [$transactionId] failed to cancel.")
-                }
-            }
-        }
-                .executeBy(taskExecutor)
+        val workerParams = WorkerParamsFactory.toData(SendVerificationMessageWorker.Params(
+                userId = userId,
+                event = event
+        ))
+        enqueueSendWork(workerParams)
     }
 
     override fun done(transactionId: String) {
-        sendVerificationMessageTask.configureWith(
-                sendVerificationMessageTask.createParamsAndLocalEcho(
-                        EventType.KEY_VERIFICATION_DONE,
-                        roomId,
-                        MessageVerificationDoneContent(
+        val event = createEventAndLocalEcho(
+                type = EventType.KEY_VERIFICATION_DONE,
+                roomId = roomId,
+                content = MessageVerificationDoneContent(
                         relatesTo = RelationDefaultContent(
                                 RelationType.REFERENCE,
                                 transactionId
                         )
-                        ).toContent(),
-                        cryptoService
+                ).toContent()
         )
-        ) {
-            callbackThread = TaskThread.DM_VERIF
-            executionThread = TaskThread.DM_VERIF
-            constraints = TaskConstraints(true)
-            retryCount = 3
+        val workerParams = WorkerParamsFactory.toData(SendVerificationMessageWorker.Params(
+                userId = userId,
+                event = event
+        ))
+        enqueueSendWork(workerParams)
     }
-                .executeBy(taskExecutor)
+
+    private fun enqueueSendWork(workerParams: Data): Pair<Operation, UUID> {
+        val workRequest = WorkManagerUtil.matrixOneTimeWorkRequestBuilder<SendVerificationMessageWorker>()
+                .setConstraints(WorkManagerUtil.workConstraints)
+                .setInputData(workerParams)
+                .setBackoffCriteria(BackoffPolicy.LINEAR, 2_000L, TimeUnit.MILLISECONDS)
+                .build()
+        return WorkManager.getInstance(context)
+                .beginUniqueWork("${roomId}_VerificationWork", ExistingWorkPolicy.APPEND, workRequest)
+                .enqueue() to workRequest.id
     }
 
     override fun createAccept(tid: String,
@@ -178,16 +270,28 @@ internal class SasTransportRoomMessage(
                 methods = methods
         )
     }
+
+    private fun createEventAndLocalEcho(localID: String = LocalEcho.createLocalEchoId(), type: String, roomId: String, content: Content): Event {
+        return Event(
+                roomId = roomId,
+                originServerTs = System.currentTimeMillis(),
+                senderId = userId,
+                eventId = localID,
+                type = type,
+                content = content,
+                unsignedData = UnsignedData(age = null, transactionId = localID)
+        ).also {
+            localEchoEventFactory.saveLocalEcho(monarchy, it)
+        }
+    }
 }
 
 internal class SasTransportRoomMessageFactory @Inject constructor(
-        private val sendVerificationMessageTask: DefaultSendVerificationMessageTask,
-        private val taskExecutor: TaskExecutor) {
+        private val monarchy: Monarchy,
+        private val localEchoEventFactory: LocalEchoEventFactory) {
 
-    fun createTransport(roomId: String,
-                        cryptoService: CryptoService,
-                        tx: SASVerificationTransaction?
+    fun createTransport(context: Context, userId: String, userDevice: String, roomId: String, tx: SASVerificationTransaction?
     ): SasTransportRoomMessage {
-        return SasTransportRoomMessage(roomId, cryptoService, tx, sendVerificationMessageTask, taskExecutor)
+        return SasTransportRoomMessage(context, userId, userDevice, roomId, monarchy, localEchoEventFactory, tx)
     }
 }

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/SasTransportToDevice.kt

@@ -19,6 +19,7 @@ import im.vector.matrix.android.api.MatrixCallback
 import im.vector.matrix.android.api.session.crypto.sas.CancelCode
 import im.vector.matrix.android.api.session.crypto.sas.SasVerificationTxState
 import im.vector.matrix.android.api.session.events.model.EventType
+import im.vector.matrix.android.api.session.room.model.message.MessageVerificationRequestContent
 import im.vector.matrix.android.internal.crypto.model.MXUsersDevicesMap
 import im.vector.matrix.android.internal.crypto.model.rest.*
 import im.vector.matrix.android.internal.crypto.tasks.SendToDeviceTask
@@ -33,6 +34,10 @@ internal class SasTransportToDevice(
         private var taskExecutor: TaskExecutor
 ) : SasTransport {
 
+    override fun sendVerificationRequest(localID: String, otherUserId: String, roomId: String, callback: (String?, MessageVerificationRequestContent?) -> Unit) {
+        // TODO "not implemented"
+    }
+
     override fun sendToOther(type: String,
                              verificationInfo: VerificationInfo,
                              nextState: SasVerificationTxState,

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/crypto/verification/SendVerificationMessageWorker.kt

@@ -0,0 +1,61 @@
+package im.vector.matrix.android.internal.crypto.verification
+
+import android.content.Context
+import androidx.work.CoroutineWorker
+import androidx.work.Data
+import androidx.work.WorkerParameters
+import com.squareup.moshi.JsonClass
+import im.vector.matrix.android.api.failure.Failure
+import im.vector.matrix.android.api.failure.MatrixError
+import im.vector.matrix.android.api.session.crypto.CryptoService
+import im.vector.matrix.android.api.session.events.model.Event
+import im.vector.matrix.android.internal.crypto.tasks.SendVerificationMessageTask
+import im.vector.matrix.android.internal.worker.WorkerParamsFactory
+import im.vector.matrix.android.internal.worker.getSessionComponent
+import javax.inject.Inject
+
+internal class SendVerificationMessageWorker constructor(context: Context, params: WorkerParameters)
+    : CoroutineWorker(context, params) {
+
+    @JsonClass(generateAdapter = true)
+    internal data class Params(
+            val userId: String,
+            val event: Event
+    )
+
+    @Inject
+    lateinit var sendVerificationMessageTask: SendVerificationMessageTask
+
+    @Inject
+    lateinit var cryptoService: CryptoService
+
+    override suspend fun doWork(): Result {
+        val params = WorkerParamsFactory.fromData<Params>(inputData)
+                ?: return Result.success(Data.Builder().putBoolean("failed", true).build())
+
+        val sessionComponent = getSessionComponent(params.userId) ?: return Result.success()
+        sessionComponent.inject(this)
+        val localId = params.event.eventId ?: ""
+        return try {
+            val eventId = sendVerificationMessageTask.execute(
+                    SendVerificationMessageTask.Params(
+                            event = params.event,
+                            cryptoService = cryptoService
+                    )
+            )
+
+            Result.success(Data.Builder().putString(localId, eventId).build())
+        } catch (exception: Throwable) {
+            if (exception.shouldBeRetried()) {
+                Result.retry()
+            } else {
+                Result.success(Data.Builder().putBoolean("failed", true).build())
+            }
+        }
+    }
+
+    private fun Throwable.shouldBeRetried(): Boolean {
+        return this is Failure.NetworkConnection
+                || (this is Failure.ServerError && error.code == MatrixError.M_LIMIT_EXCEEDED)
+    }
+}

matrix-sdk-android/src/main/java/im/vector/matrix/android/internal/session/SessionComponent.kt

@@ -21,6 +21,7 @@ import dagger.Component
 import im.vector.matrix.android.api.auth.data.SessionParams
 import im.vector.matrix.android.api.session.Session
 import im.vector.matrix.android.internal.crypto.CryptoModule
+import im.vector.matrix.android.internal.crypto.verification.SendVerificationMessageWorker
 import im.vector.matrix.android.internal.di.MatrixComponent
 import im.vector.matrix.android.internal.di.SessionAssistedInjectModule
 import im.vector.matrix.android.internal.network.NetworkConnectivityChecker
@@ -98,6 +99,8 @@ internal interface SessionComponent {
 
     fun inject(addHttpPusherWorker: AddHttpPusherWorker)
 
+    fun inject(sendVerificationMessageWorker: SendVerificationMessageWorker)
+
     @Component.Factory
     interface Factory {
         fun create(

vector/src/main/java/im/vector/riotx/features/crypto/verification/VerificationBottomSheetViewModel.kt

@@ -109,7 +109,7 @@ class VerificationBottomSheetViewModel @AssistedInject constructor(@Assisted ini
             is VerificationAction.RequestVerificationByDM -> {
 //                session
                 setState {
-                    copy(pendingRequest = session.getSasVerificationService().requestKeyVerificationInDMs(otherUserId, roomId, null))
+                    copy(pendingRequest = session.getSasVerificationService().requestKeyVerificationInDMs(otherUserId, roomId))
                 }
             }
             is VerificationAction.StartSASVerification    -> {

vector/src/main/java/im/vector/riotx/features/home/room/detail/RoomDetailViewModel.kt

@@ -398,7 +398,7 @@ class RoomDetailViewModel @AssistedInject constructor(@Assisted initialState: Ro
                             popDraft()
                         }
                         is ParsedCommand.VerifyUser               -> {
-                            session.getSasVerificationService().requestKeyVerificationInDMs(slashCommandResult.userId, room.roomId, null)
+                            session.getSasVerificationService().requestKeyVerificationInDMs(slashCommandResult.userId, room.roomId)
                             _sendMessageResultLiveData.postLiveEvent(SendMessageResult.SlashCommandHandled())
                             popDraft()
                         }