diff --git a/lib/media/media-utils.js b/lib/media/media-utils.js
--- a/lib/media/media-utils.js
+++ b/lib/media/media-utils.js
@@ -2,7 +2,11 @@
 
 import invariant from 'invariant';
 
-import type { Media } from '../types/media-types.js';
+import type {
+  EncryptedImage,
+  EncryptedVideo,
+  Media,
+} from '../types/media-types.js';
 import type {
   MultimediaMessageInfo,
   RawMultimediaMessageInfo,
@@ -79,6 +83,24 @@
   return `${localUploadPrefix}${nextLocalUploadID++}`;
 }
 
+/**
+ * Returns effective multimedia blob URI for encrypted image or video
+ */
+function encryptedMediaBlobURI(media: EncryptedImage | EncryptedVideo): string {
+  const uri = media.blobURI ?? media.holder;
+  invariant(uri, 'encrypted media has no blob URI');
+  return uri;
+}
+
+/**
+ * Returns effective thumbnail blob URI for encrypted video
+ */
+function encryptedVideoThumbnailBlobURI(media: EncryptedVideo): string {
+  const uri = media.thumbnailBlobURI ?? media.thumbnailHolder;
+  invariant(uri, 'encrypted thumbnail has no blob URI');
+  return uri;
+}
+
 export {
   maxDimensions,
   contentStringForMediaArray,
@@ -87,4 +109,6 @@
   isMediaBlobServiceHosted,
   getNextLocalUploadID,
   fetchableMediaURI,
+  encryptedMediaBlobURI,
+  encryptedVideoThumbnailBlobURI,
 };