diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/CryptoModule.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/CryptoModule.kt
index eb898188ae..dc3b99fcb8 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/CryptoModule.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/CryptoModule.kt
@@ -24,6 +24,7 @@ import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.SupervisorJob
 import org.matrix.android.sdk.api.session.crypto.CryptoService
 import org.matrix.android.sdk.api.session.crypto.crosssigning.CrossSigningService
+import org.matrix.android.sdk.api.session.crypto.verification.VerificationService
 import org.matrix.android.sdk.internal.crypto.api.CryptoApi
 import org.matrix.android.sdk.internal.crypto.crosssigning.ComputeTrustTask
 import org.matrix.android.sdk.internal.crypto.crosssigning.DefaultComputeTrustTask
@@ -88,6 +89,7 @@ import org.matrix.android.sdk.internal.crypto.tasks.SetDeviceNameTask
 import org.matrix.android.sdk.internal.crypto.tasks.UploadKeysTask
 import org.matrix.android.sdk.internal.crypto.tasks.UploadSignaturesTask
 import org.matrix.android.sdk.internal.crypto.tasks.UploadSigningKeysTask
+import org.matrix.android.sdk.internal.crypto.verification.RustVerificationService
 import org.matrix.android.sdk.internal.database.RealmKeysUtils
 import org.matrix.android.sdk.internal.di.CryptoDatabase
 import org.matrix.android.sdk.internal.di.SessionFilesDirectory
@@ -95,11 +97,6 @@ import org.matrix.android.sdk.internal.di.UserMd5
 import org.matrix.android.sdk.internal.session.SessionScope
 import org.matrix.android.sdk.internal.session.cache.ClearCacheTask
 import org.matrix.android.sdk.internal.session.cache.RealmClearCacheTask
-import io.realm.RealmConfiguration
-import kotlinx.coroutines.CoroutineScope
-import kotlinx.coroutines.SupervisorJob
-import org.matrix.android.sdk.api.session.crypto.verification.VerificationService
-import org.matrix.android.sdk.internal.crypto.verification.RustVerificationService
 import retrofit2.Retrofit
 import java.io.File
 
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/DefaultCryptoService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/DefaultCryptoService.kt
index 021b4ff42d..526797d3be 100755
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/DefaultCryptoService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/DefaultCryptoService.kt
@@ -20,8 +20,6 @@ import android.content.Context
 import androidx.annotation.VisibleForTesting
 import androidx.lifecycle.LiveData
 import androidx.paging.PagedList
-import com.squareup.moshi.Types
-import dagger.Lazy
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.CoroutineScope
 import kotlinx.coroutines.async
@@ -39,14 +37,12 @@ import org.matrix.android.sdk.api.auth.UserInteractiveAuthInterceptor
 import org.matrix.android.sdk.api.crypto.MXCryptoConfig
 import org.matrix.android.sdk.api.extensions.tryOrNull
 import org.matrix.android.sdk.api.failure.Failure
-import org.matrix.android.sdk.api.failure.MatrixError
 import org.matrix.android.sdk.api.listeners.ProgressListener
 import org.matrix.android.sdk.api.session.crypto.CryptoService
 import org.matrix.android.sdk.api.session.crypto.MXCryptoError
 import org.matrix.android.sdk.api.session.crypto.crosssigning.CrossSigningService
 import org.matrix.android.sdk.api.session.crypto.keysbackup.KeysBackupService
 import org.matrix.android.sdk.api.session.crypto.keyshare.GossipingRequestListener
-import org.matrix.android.sdk.api.session.crypto.verification.VerificationService
 import org.matrix.android.sdk.api.session.events.model.Content
 import org.matrix.android.sdk.api.session.events.model.Event
 import org.matrix.android.sdk.api.session.events.model.EventType
@@ -58,26 +54,8 @@ import org.matrix.android.sdk.api.session.room.model.RoomMemberContent
 import org.matrix.android.sdk.api.session.sync.model.DeviceListResponse
 import org.matrix.android.sdk.api.session.sync.model.DeviceOneTimeKeysCountSyncResponse
 import org.matrix.android.sdk.api.session.sync.model.ToDeviceSyncResponse
-import org.matrix.android.sdk.api.util.JsonDict
-import org.matrix.android.sdk.internal.auth.registration.handleUIA
 import org.matrix.android.sdk.internal.crypto.crosssigning.DeviceTrustLevel
 import org.matrix.android.sdk.internal.crypto.keysbackup.RustKeyBackupService
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.BackupKeysResult
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.CreateKeysBackupVersionBody
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeysBackupData
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeysVersion
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.KeysVersionResult
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.RoomKeysBackupData
-import org.matrix.android.sdk.internal.crypto.keysbackup.model.rest.UpdateKeysBackupVersionBody
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.CreateKeysBackupVersionTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.DeleteBackupTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.GetKeysBackupLastVersionTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.GetKeysBackupVersionTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.GetRoomSessionDataTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.GetRoomSessionsDataTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.GetSessionsDataTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.StoreSessionsDataTask
-import org.matrix.android.sdk.internal.crypto.keysbackup.tasks.UpdateKeysBackupVersionTask
 import org.matrix.android.sdk.internal.crypto.model.CryptoDeviceInfo
 import org.matrix.android.sdk.internal.crypto.model.ImportRoomKeysResult
 import org.matrix.android.sdk.internal.crypto.model.MXEncryptEventContentResult
@@ -96,7 +74,6 @@ import org.matrix.android.sdk.internal.crypto.tasks.GetDevicesTask
 import org.matrix.android.sdk.internal.crypto.tasks.SetDeviceNameTask
 import org.matrix.android.sdk.internal.crypto.verification.RustVerificationService
 import org.matrix.android.sdk.internal.di.DeviceId
-import org.matrix.android.sdk.internal.di.SessionFilesDirectory
 import org.matrix.android.sdk.internal.di.UserId
 import org.matrix.android.sdk.internal.extensions.foldToCallback
 import org.matrix.android.sdk.internal.session.SessionScope
@@ -152,6 +129,7 @@ internal class DefaultCryptoService @Inject constructor(
         private val sender: RequestSender,
         private val crossSigningService: CrossSigningService,
         private val verificationService: RustVerificationService,
+        private val keysBackupService: RustKeyBackupService,
         private val olmMachineProvider: OlmMachineProvider
 ) : CryptoService {
 
@@ -165,11 +143,6 @@ internal class DefaultCryptoService @Inject constructor(
 
 //    private val deviceObserver: DeviceUpdateObserver = DeviceUpdateObserver()
 
-    // The key backup service.
-    private var keysBackupService: RustKeyBackupService? = null
-
-    private val deviceObserver: DeviceUpdateObserver = DeviceUpdateObserver()
-
     // Locks for some of our operations
     private val keyClaimLock: Mutex = Mutex()
     private val outgoingRequestsLock: Mutex = Mutex()
@@ -335,7 +308,6 @@ internal class DefaultCryptoService @Inject constructor(
 
         try {
             setRustLogger()
-            keysBackupService = RustKeyBackupService(machine, sender, coroutineDispatchers, cryptoCoroutineScope)
             Timber.v(
                     "## CRYPTO | Successfully started up an Olm machine for " +
                             "${userId}, ${deviceId}, identity keys: ${this.olmMachine.identityKeys()}")
@@ -346,7 +318,7 @@ internal class DefaultCryptoService @Inject constructor(
         // We try to enable key backups, if the backup version on the server is trusted,
         // we're gonna continue backing up.
         tryOrNull {
-            keysBackupService!!.checkAndStartKeysBackup()
+            keysBackupService.checkAndStartKeysBackup()
         }
 
         // Open the store
@@ -370,12 +342,7 @@ internal class DefaultCryptoService @Inject constructor(
     /**
      * @return the Keys backup Service
      */
-    override fun keysBackupService(): KeysBackupService {
-        if (keysBackupService == null) {
-            internalStart()
-        }
-        return keysBackupService!!
-    }
+    override fun keysBackupService() = keysBackupService
 
     /**
      * @return the VerificationService
@@ -400,7 +367,7 @@ internal class DefaultCryptoService @Inject constructor(
             // This could be omitted but then devices might be waiting for the next
             sendOutgoingRequests()
 
-            keysBackupService?.maybeBackupKeys()
+            keysBackupService.maybeBackupKeys()
         }
 
         cryptoCoroutineScope.launch(coroutineDispatchers.crypto) {
@@ -431,7 +398,7 @@ internal class DefaultCryptoService @Inject constructor(
 
     override fun getCryptoDeviceInfo(userId: String): List<CryptoDeviceInfo> {
         return runBlocking {
-            this@DefaultCryptoService.olmMachine.getCryptoDeviceInfo(userId) ?: listOf()
+            this@DefaultCryptoService.olmMachine.getCryptoDeviceInfo(userId)
         }
     }
 
@@ -633,6 +600,7 @@ internal class DefaultCryptoService @Inject constructor(
             olmMachine.updateTrackedUsers(userIds)
         }
     }
+
     private fun getRoomUserIds(roomId: String): List<String> {
         val encryptForInvitedMembers = isEncryptionEnabledForInvitedUser() &&
                 shouldEncryptForInvitedMembers(roomId)
@@ -726,7 +694,7 @@ internal class DefaultCryptoService @Inject constructor(
 
                         notifyRoomKeyReceived(roomId, sessionId)
                     }
-                    EventType.SEND_SECRET -> {
+                    EventType.SEND_SECRET        -> {
                         // The rust-sdk will clear this event if it's invalid, this will produce an invalid base64 error
                         // when we try to construct the recovery key.
                         val secretContent = event.getClearContent().toModel<SecretSendEventContent>() ?: return@forEach
@@ -808,7 +776,6 @@ internal class DefaultCryptoService @Inject constructor(
                     cryptoSessionInfoProvider.updateShieldForRoom(roomId, shield)
                 }
             }
-
         } catch (throwable: Throwable) {
             Timber.e(throwable, "## CRYPTO | doKeyDownloadForUsers(): error")
         }
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/MXOlmDevice.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/MXOlmDevice.kt
index 441dfe4a5d..7a3ae7c1b9 100755
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/MXOlmDevice.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/MXOlmDevice.kt
@@ -41,6 +41,7 @@ import java.net.URLEncoder
 import javax.inject.Inject
 
 // The libolm wrapper.
+@Deprecated("rust")
 @SessionScope
 internal class MXOlmDevice @Inject constructor(
         /**
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/RustCrossSigningService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/RustCrossSigningService.kt
index bf5d0eca9e..4c9d62f610 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/RustCrossSigningService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/RustCrossSigningService.kt
@@ -30,18 +30,18 @@ import org.matrix.android.sdk.internal.crypto.crosssigning.DeviceTrustResult
 import org.matrix.android.sdk.internal.crypto.crosssigning.UserTrustResult
 import org.matrix.android.sdk.internal.crypto.crosssigning.isVerified
 import org.matrix.android.sdk.internal.crypto.store.PrivateKeysInfo
-import org.matrix.android.sdk.internal.di.SessionId
 import org.matrix.android.sdk.internal.di.UserId
 import org.matrix.android.sdk.internal.extensions.foldToCallback
 import javax.inject.Inject
 
 internal class RustCrossSigningService @Inject constructor(
-        @SessionId private val sessionId: String,
+//        @SessionId private val sessionId: String,
         @UserId private val myUserId: String,
         private val olmMachineProvider: OlmMachineProvider
 ) : CrossSigningService {
 
     val olmMachine = olmMachineProvider.olmMachine
+
     /**
      * Is our own device signed by our own cross signing identity
      */
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/actions/MegolmSessionDataImporter.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/actions/MegolmSessionDataImporter.kt
index 0d78f68e5c..e0748a0d1f 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/actions/MegolmSessionDataImporter.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/actions/MegolmSessionDataImporter.kt
@@ -28,6 +28,7 @@ import org.matrix.android.sdk.internal.crypto.store.IMXCryptoStore
 import timber.log.Timber
 import javax.inject.Inject
 
+@Deprecated("rust")
 internal class MegolmSessionDataImporter @Inject constructor(private val olmDevice: MXOlmDevice,
                                                              private val roomDecryptorProvider: RoomDecryptorProvider,
                                                              private val outgoingGossipingRequestManager: OutgoingGossipingRequestManager,
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXDecrypting.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXDecrypting.kt
index 79c7608cbf..b9cfd942ce 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXDecrypting.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXDecrypting.kt
@@ -26,6 +26,7 @@ import org.matrix.android.sdk.internal.crypto.keysbackup.DefaultKeysBackupServic
 /**
  * An interface for decrypting data
  */
+@Deprecated("rust")
 internal interface IMXDecrypting {
 
     /**
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXEncrypting.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXEncrypting.kt
index 5294429198..b0f411cbcc 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXEncrypting.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXEncrypting.kt
@@ -21,6 +21,7 @@ import org.matrix.android.sdk.api.session.events.model.Content
 /**
  * An interface for encrypting data
  */
+@Deprecated("rust")
 internal interface IMXEncrypting {
 
     /**
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXGroupEncryption.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXGroupEncryption.kt
index 1fd5061a65..7d191861e7 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXGroupEncryption.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXGroupEncryption.kt
@@ -16,6 +16,7 @@
 
 package org.matrix.android.sdk.internal.crypto.algorithms
 
+@Deprecated("rust")
 internal interface IMXGroupEncryption {
 
     /**
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXWithHeldExtension.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXWithHeldExtension.kt
index 91f10adf4c..7a03217ea5 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXWithHeldExtension.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/IMXWithHeldExtension.kt
@@ -18,6 +18,7 @@ package org.matrix.android.sdk.internal.crypto.algorithms
 
 import org.matrix.android.sdk.internal.crypto.model.event.RoomKeyWithHeldContent
 
+@Deprecated("rust")
 internal interface IMXWithHeldExtension {
     fun onRoomKeyWithHeldEvent(withHeldInfo: RoomKeyWithHeldContent)
 }
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt
index 031bb4e194..5e748d3739 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/algorithms/megolm/MXMegolmEncryption.kt
@@ -43,6 +43,7 @@ import org.matrix.android.sdk.internal.util.JsonCanonicalizer
 import org.matrix.android.sdk.internal.util.convertToUTF8
 import timber.log.Timber
 
+@Deprecated("in favour of rust")
 internal class MXMegolmEncryption(
         // The id of the room we will be sending to.
         private val roomId: String,
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt
index b20168eaa3..b0c7c8b610 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/DefaultKeysBackupService.kt
@@ -99,6 +99,7 @@ import kotlin.random.Random
  * to the user's homeserver.
  */
 @SessionScope
+@Deprecated("use rust")
 internal class DefaultKeysBackupService @Inject constructor(
         @UserId private val userId: String,
         private val credentials: Credentials,
diff --git a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/RustKeyBackupService.kt b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/RustKeyBackupService.kt
index 3b9ce5b67e..0ec13ced19 100644
--- a/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/RustKeyBackupService.kt
+++ b/matrix-sdk-android/src/main/java/org/matrix/android/sdk/internal/crypto/keysbackup/RustKeyBackupService.kt
@@ -38,6 +38,7 @@ import org.matrix.android.sdk.api.session.crypto.keysbackup.KeysBackupStateListe
 import org.matrix.android.sdk.internal.crypto.MXCRYPTO_ALGORITHM_MEGOLM_BACKUP
 import org.matrix.android.sdk.internal.crypto.MegolmSessionData
 import org.matrix.android.sdk.internal.crypto.OlmMachine
+import org.matrix.android.sdk.internal.crypto.OlmMachineProvider
 import org.matrix.android.sdk.internal.crypto.RequestSender
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.KeysBackupVersionTrust
 import org.matrix.android.sdk.internal.crypto.keysbackup.model.MegolmBackupAuthData
@@ -71,7 +72,7 @@ import kotlin.random.Random
  */
 @SessionScope
 internal class RustKeyBackupService @Inject constructor(
-        private val olmMachine: OlmMachine,
+        olmMachineProvider: OlmMachineProvider,
         private val sender: RequestSender,
         private val coroutineDispatchers: MatrixCoroutineDispatchers,
         private val cryptoCoroutineScope: CoroutineScope,
@@ -85,6 +86,8 @@ internal class RustKeyBackupService @Inject constructor(
 
     private val keysBackupStateManager = KeysBackupStateManager(uiHandler)
 
+    private val olmMachine = olmMachineProvider.olmMachine
+
     // The backup version
     override var keysBackupVersion: KeysVersionResult? = null
         private set