def import_rsa_publickey_from_file(filepath):
<EOL>securesystemslib.formats.PATH_SCHEMA.check_match(filepath)<EOL>with open(filepath, '<STR_LIT:rb>') as file_object:<EOL><INDENT>rsa_pubkey_pem = file_object.read().decode('<STR_LIT:utf-8>')<EOL><DEDENT>try:<EOL><INDENT>rsakey_dict = securesystemslib.keys.import_rsakey_from_public_pem(rsa_pubkey_pem)<EOL><DEDENT>except securesystemslib.exceptions.FormatError as e:<EOL><INDENT>raise securesystemslib.exceptions.Error('<STR_LIT>'<EOL>'<STR_LIT>' + repr(str(e)))<EOL><DEDENT>return rsakey_dict<EOL>
<Purpose>
  Import the RSA key stored in 'filepath'.  The key object returned is in the
  format 'securesystemslib.formats.RSAKEY_SCHEMA'.  If the RSA PEM in
  'filepath' contains a private key, it is discarded.

<Arguments>
  filepath:
    <filepath>.pub file, an RSA PEM file.

<Exceptions>
  securesystemslib.exceptions.FormatError, if 'filepath' is improperly
  formatted.

  securesystemslib.exceptions.Error, if a valid RSA key object cannot be
  generated.  This may be caused by an improperly formatted PEM file.

<Side Effects>
  'filepath' is read and its contents extracted.

<Returns>
  An RSA key object conformant to 'securesystemslib.formats.RSAKEY_SCHEMA'.