(defun file-hash (fname)
    "Return sha256 of file."
    (interactive)
    (with-temp-buffer
      (call-process "sha256sum" nil t nil "-b" fname)
      (buffer-substring-no-properties (point-min) (+ (point-min) 64))))

  (defun string-hash (str)
    "Return sha256 of string."
    (interactive)
    (upcase (secure-hash 'sha256 str)))