pkey.getPrivateKey: use password callback

Author: kunkku

src/openssl.c

@@ -3969,7 +3969,7 @@ static int pk_getPrivateKey(lua_State *L) {
 			return luaL_error(L, "pkey:getPrivateKey: unknown cipher: %s", cname);
 	}
 
-	if (!PEM_write_bio_PrivateKey(getbio(L), key, cipher, pass, pass ? strlen(pass) : 0, 0, 0))
+	if (!PEM_write_bio_PrivateKey(getbio(L), key, cipher, NULL, 0, pem_pw_cb, pass))
 		return auxL_error(L, auxL_EOPENSSL, "pkey:getPrivateKey");
 	pushbiostring(L);
 	return 1;