diff --git a/app/src/main/java/org/thoughtcrime/securesms/keyvalue/RegistrationValues.kt b/app/src/main/java/org/thoughtcrime/securesms/keyvalue/RegistrationValues.kt
index fa4d6d5024..d4dbffcb48 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/keyvalue/RegistrationValues.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/keyvalue/RegistrationValues.kt
@@ -23,6 +23,7 @@ class RegistrationValues internal constructor(store: KeyValueStore) : SignalStor
     private const val RESTORE_BACKUP_MEDIA_SIZE = "registration.restore_backup_media_size"
     private const val IS_OTHER_DEVICE_ANDROID = "registration.is_other_device_android"
     private const val RESTORING_ON_NEW_DEVICE = "registration.restoring_on_new_device"
+    private const val IN_PROGRESS_DATA_BLOB_URI = "registration.in_progress_data_blob_uri"
 
     @VisibleForTesting
     const val RESTORE_DECISION_STATE = "registration.restore_decision_state.2"
@@ -81,6 +82,9 @@ class RegistrationValues internal constructor(store: KeyValueStore) : SignalStor
   var sessionId: String? by stringValue(SESSION_ID, null)
   var sessionE164: String? by stringValue(SESSION_E164, null)
 
+  /** URI of the encrypted [org.signal.core.util.contentproviders.BlobProvider] blob holding the in-progress registration data, if any. */
+  var inProgressRegistrationDataBlobUri: String? by stringValue(IN_PROGRESS_DATA_BLOB_URI, null)
+
   var isOtherDeviceAndroid: Boolean by booleanValue(IS_OTHER_DEVICE_ANDROID, false)
   var restoreMethodToken: String? by stringValue(RESTORE_METHOD_TOKEN, null)
   var restoreBackupMediaSize: Long by longValue(RESTORE_BACKUP_MEDIA_SIZE, 0L)
diff --git a/app/src/main/java/org/thoughtcrime/securesms/registration/v2/AppRegistrationStorageController.kt b/app/src/main/java/org/thoughtcrime/securesms/registration/v2/AppRegistrationStorageController.kt
index 08bdd57262..59b796c828 100644
--- a/app/src/main/java/org/thoughtcrime/securesms/registration/v2/AppRegistrationStorageController.kt
+++ b/app/src/main/java/org/thoughtcrime/securesms/registration/v2/AppRegistrationStorageController.kt
@@ -7,6 +7,7 @@ package org.thoughtcrime.securesms.registration.v2
 
 import android.content.Context
 import android.net.Uri
+import androidx.core.net.toUri
 import androidx.documentfile.provider.DocumentFile
 import kotlinx.coroutines.CancellationException
 import kotlinx.coroutines.Dispatchers
@@ -51,6 +52,7 @@ import org.thoughtcrime.securesms.database.SignalDatabase
 import org.thoughtcrime.securesms.database.model.databaseprotos.LinkedDeviceInfo
 import org.thoughtcrime.securesms.database.model.databaseprotos.LocalRegistrationMetadata
 import org.thoughtcrime.securesms.database.model.databaseprotos.RestoreDecisionState
+import org.thoughtcrime.securesms.dependencies.AppDependencies
 import org.thoughtcrime.securesms.keyvalue.Completed
 import org.thoughtcrime.securesms.keyvalue.NewAccount
 import org.thoughtcrime.securesms.keyvalue.PhoneNumberPrivacyValues
@@ -108,6 +110,10 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
   }
 
   override suspend fun clearAllData() = withContext(Dispatchers.IO) {
+    SignalStore.registration.inProgressRegistrationDataBlobUri?.toUri()?.let { AppDependencies.blobs.delete(context, it) }
+    SignalStore.registration.inProgressRegistrationDataBlobUri = null
+
+    // Best-effort cleanup of the legacy plaintext file written by older builds.
     File(context.cacheDir, TEMP_PROTO_FILENAME).takeIf { it.exists() }?.delete()
     Unit
   }
@@ -151,15 +157,11 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
   }
 
   override suspend fun readInProgressRegistrationData(): RegistrationData = withContext(Dispatchers.IO) {
-    val file = File(context.cacheDir, TEMP_PROTO_FILENAME)
-    if (file.exists()) {
-      try {
-        RegistrationData.ADAPTER.decode(file.readBytes())
-      } catch (e: Exception) {
-        Log.w(TAG, "Failed to decode registration data, returning empty.", e)
-        RegistrationData()
-      }
-    } else {
+    val uri = SignalStore.registration.inProgressRegistrationDataBlobUri?.toUri() ?: return@withContext RegistrationData()
+    try {
+      AppDependencies.blobs.getStream(context, uri).use { RegistrationData.ADAPTER.decode(it) }
+    } catch (e: Exception) {
+      Log.w(TAG, "Failed to read/decode in-progress registration data, returning empty.", e)
       RegistrationData()
     }
   }
@@ -529,7 +531,14 @@ class AppRegistrationStorageController(private val context: Context) : StorageCo
 
   private suspend fun writeRegistrationData(data: RegistrationData) = withContext(Dispatchers.IO) {
     val stamped = data.newBuilder().lastUpdatedMillis(System.currentTimeMillis()).build()
-    val file = File(context.cacheDir, TEMP_PROTO_FILENAME)
-    file.writeBytes(RegistrationData.ADAPTER.encode(stamped))
+
+    val previousUri = SignalStore.registration.inProgressRegistrationDataBlobUri?.toUri()
+    val newUri = AppDependencies.blobs
+      .forData(RegistrationData.ADAPTER.encode(stamped))
+      .createForMultipleSessionsOnDisk(context)
+
+    SignalStore.registration.inProgressRegistrationDataBlobUri = newUri.toString()
+    previousUri?.let { AppDependencies.blobs.delete(context, it) }
+    Unit
   }
 }