backend/src/SignDocument/Controller/DigitalSignatureController.php

@@ -30,7 +30,7 @@ class DigitalSignatureController extends AbstractController
         return $this->createJsonResponse(
             [
                 'hash' => $response->hash,
-                'content' => $response->content,
+                'content' => base64_encode($response->content),
             ]
         );
     }