code: def clear_to_enc_filename(fname):
      
      if not fname.lower().endswith('.json'):
          raise CredkeepException('Invalid filetype')
  
      if fname.lower().endswith('.enc.json'):
          raise CredkeepException('File already encrypted')
  
      enc_fname = fname[:-4] + 'enc.json'
  
      return enc_fname if exists(enc_fname) else None
docs: Converts the filename of a cleartext file and convert it to an encrypted filename
  
      :param fname:
      :return: filename of encrypted secret file if found, else None