I think the problem is that I have org-mobile-directory set to

  "/ssh:foo.example.com:/usr/home/gdt/ORG"

then in here the encryption tries to be done in place, which means (I
think) a tramp pathname is passed to openssl.

Probably agendas.org needs to be created in a staging area and then the
encrypted version moved with copy-file.



(defun org-mobile-create-sumo-agenda ()
  "Create a file that contains all custom agenda views."
  (interactive)
  (let* ((file (expand-file-name "agendas.org"
				 org-mobile-directory))
	 (file1 (if org-mobile-use-encryption
		    org-mobile-encryption-tempfile
		  file))
	 (sumo (org-mobile-sumo-agenda-command))
	 (org-agenda-custom-commands
	  (list (append sumo (list (list file1)))))
	 (org-mobile-creating-agendas t))
    (unless (file-writable-p file1)
      (error "Cannot write to file %s" file1))
    (when sumo
      (org-store-agenda-views))
    (when org-mobile-use-encryption
      (org-mobile-encrypt-file file1 file)
      (delete-file file1))))