diff --git a/libsession/src/main/java/org/session/libsession/messaging/jobs/AttachmentUploadJob.kt b/libsession/src/main/java/org/session/libsession/messaging/jobs/AttachmentUploadJob.kt
index a4ef41431d..72c42b03a5 100644
--- a/libsession/src/main/java/org/session/libsession/messaging/jobs/AttachmentUploadJob.kt
+++ b/libsession/src/main/java/org/session/libsession/messaging/jobs/AttachmentUploadJob.kt
@@ -3,8 +3,10 @@ package org.session.libsession.messaging.jobs
 import com.esotericsoftware.kryo.Kryo
 import com.esotericsoftware.kryo.io.Input
 import com.esotericsoftware.kryo.io.Output
+import nl.komponents.kovenant.Promise
 import org.session.libsession.messaging.MessagingModuleConfiguration
 import org.session.libsession.messaging.file_server.FileServerAPI
+import org.session.libsession.messaging.file_server.FileServerAPIV2
 import org.session.libsession.messaging.messages.Message
 import org.session.libsession.messaging.open_groups.OpenGroupAPIV2
 import org.session.libsession.messaging.sending_receiving.MessageSender
@@ -15,6 +17,7 @@ import org.session.libsignal.service.api.messages.SignalServiceAttachmentStream
 import org.session.libsignal.service.internal.crypto.PaddingInputStream
 import org.session.libsignal.service.internal.push.PushAttachmentData
 import org.session.libsignal.service.internal.push.http.AttachmentCipherOutputStreamFactory
+import org.session.libsignal.service.internal.push.http.DigestingRequestBody
 import org.session.libsignal.service.internal.util.Util
 import org.session.libsignal.service.loki.PlaintextOutputStreamFactory
 import org.session.libsignal.utilities.logging.Log
@@ -45,27 +48,29 @@ class AttachmentUploadJob(val attachmentID: Long, val threadID: String, val mess
 
     override fun execute() {
         try {
-            val attachment = MessagingModuleConfiguration.shared.messageDataProvider.getScaledSignalAttachmentStream(attachmentID)
+            val storage = MessagingModuleConfiguration.shared.storage
+            val messageDataProvider = MessagingModuleConfiguration.shared.messageDataProvider
+            val attachment = messageDataProvider.getScaledSignalAttachmentStream(attachmentID)
                 ?: return handleFailure(Error.NoAttachment)
-            val usePadding = false
-            val openGroupV2 = MessagingModuleConfiguration.shared.storage.getV2OpenGroup(threadID)
-            val openGroup = MessagingModuleConfiguration.shared.storage.getOpenGroup(threadID)
-            val server = openGroupV2?.server ?: openGroup?.server ?: FileServerAPI.shared.server
-            val shouldEncrypt = (openGroup == null && openGroupV2 == null) // Encrypt if this isn't an open group
-            val attachmentKey = Util.getSecretBytes(64)
-            val paddedLength = if (usePadding) PaddingInputStream.getPaddedSize(attachment.length) else attachment.length
-            val dataStream = if (usePadding) PaddingInputStream(attachment.inputStream, attachment.length) else attachment.inputStream
-            val ciphertextLength = if (shouldEncrypt) AttachmentCipherOutputStream.getCiphertextLength(paddedLength) else attachment.length
-            val outputStreamFactory = if (shouldEncrypt) AttachmentCipherOutputStreamFactory(attachmentKey) else PlaintextOutputStreamFactory()
-            val attachmentData = PushAttachmentData(attachment.contentType, dataStream, ciphertextLength, outputStreamFactory, attachment.listener)
-            val uploadResult = if (openGroupV2 != null) {
-                val dataBytes = attachmentData.data.readBytes()
-                val result = OpenGroupAPIV2.upload(dataBytes, openGroupV2.room, openGroupV2.server).get()
-                DotNetAPI.UploadResult(result, "${openGroupV2.server}/files/$result", byteArrayOf())
-            } else {
-                FileServerAPI.shared.uploadAttachment(server, attachmentData)
+            val v2OpenGroup = storage.getV2OpenGroup(threadID)
+            val v1OpenGroup = storage.getOpenGroup(threadID)
+            if (v2OpenGroup != null) {
+                val keyAndResult = upload(attachment, v2OpenGroup.server, false) {
+                    OpenGroupAPIV2.upload(it, v2OpenGroup.room, v2OpenGroup.server)
+                }
+                handleSuccess(attachment, keyAndResult.first, keyAndResult.second)
+            } else if (v1OpenGroup == null) {
+                val keyAndResult = upload(attachment, FileServerAPIV2.DEFAULT_SERVER, true) {
+                    FileServerAPIV2.upload(it)
+                }
+                handleSuccess(attachment, keyAndResult.first, keyAndResult.second)
+            } else { // V1 open group
+                val server = v1OpenGroup.server
+                val pushData = PushAttachmentData(attachment.contentType, attachment.inputStream,
+                    attachment.length, PlaintextOutputStreamFactory(), attachment.listener)
+                val result = FileServerAPI.shared.uploadAttachment(server, pushData)
+                handleSuccess(attachment, ByteArray(0), result)
             }
-            handleSuccess(attachment, attachmentKey, uploadResult)
         } catch (e: java.lang.Exception) {
             if (e == Error.NoAttachment) {
                 this.handlePermanentFailure(e)
@@ -77,6 +82,19 @@ class AttachmentUploadJob(val attachmentID: Long, val threadID: String, val mess
         }
     }
 
+    private fun upload(attachment: SignalServiceAttachmentStream, server: String, encrypt: Boolean, upload: (ByteArray) -> Promise<Long, Exception>): Pair<ByteArray, DotNetAPI.UploadResult> {
+        val key = if (encrypt) Util.getSecretBytes(64) else ByteArray(0)
+        val rawLength = attachment.length
+        val length = if (encrypt) PaddingInputStream.getPaddedSize(rawLength) else rawLength
+        val stream = if (encrypt) PaddingInputStream(attachment.inputStream, rawLength) else attachment.inputStream
+        val ciphertextLength = if (encrypt) AttachmentCipherOutputStream.getCiphertextLength(length) else rawLength
+        val outputStreamFactory = if (encrypt) AttachmentCipherOutputStreamFactory(key) else PlaintextOutputStreamFactory()
+        val pushData = PushAttachmentData(attachment.contentType, stream, ciphertextLength, outputStreamFactory, attachment.listener)
+        val file = DigestingRequestBody(pushData.data, outputStreamFactory, attachment.contentType, pushData.dataSize, attachment.listener)
+        val id = upload(pushData.data.readBytes()).get()
+        return Pair(key, DotNetAPI.UploadResult(id, "${server}/files/$id", file.transmittedDigest))
+    }
+
     private fun handleSuccess(attachment: SignalServiceAttachmentStream, attachmentKey: ByteArray, uploadResult: DotNetAPI.UploadResult) {
         Log.d(TAG, "Attachment uploaded successfully.")
         delegate?.handleJobSucceeded(this)
diff --git a/libsession/src/main/java/org/session/libsession/utilities/AESGCM.kt b/libsession/src/main/java/org/session/libsession/utilities/AESGCM.kt
index f5a170d8bd..102ef8dc1d 100644
--- a/libsession/src/main/java/org/session/libsession/utilities/AESGCM.kt
+++ b/libsession/src/main/java/org/session/libsession/utilities/AESGCM.kt
@@ -12,16 +12,15 @@ import javax.crypto.spec.SecretKeySpec
 
 @WorkerThread
 internal object AESGCM {
-
-    internal data class EncryptionResult(
-            internal val ciphertext: ByteArray,
-            internal val symmetricKey: ByteArray,
-            internal val ephemeralPublicKey: ByteArray
-    )
-
     internal val gcmTagSize = 128
     internal val ivSize = 12
 
+    internal data class EncryptionResult(
+        internal val ciphertext: ByteArray,
+        internal val symmetricKey: ByteArray,
+        internal val ephemeralPublicKey: ByteArray
+    )
+
     /**
      * Sync. Don't call from the main thread.
      */
diff --git a/libsession/src/main/java/org/session/libsession/utilities/mentions/Mention.kt b/libsession/src/main/java/org/session/libsession/utilities/mentions/Mention.kt
deleted file mode 100644
index e69de29bb2..0000000000