docs: function _jws_generateSignatureValueBySI_PemPrvKey(sHead, sPayload, sSI, sPemPrvKey) {
  	var rsa = new RSAKey();
  	rsa.readPrivateKeyFromPEMString(sPemPrvKey);
  	var hashAlg = _jws_getHashAlgFromHead(sHead);
  	var sigValue = rsa.signString(sSI, hashAlg);
  	return sigValue;
      }