We present new invariants, APN-extendibility criterion and a backtracking approach to identify several numerical facts supporting the conjecture that the set of 6-bit \APN functions is limited to 14 CCZ-classes.

翻译：我们提出了新的不变量、APN可扩展性准则以及回溯方法，以识别支持以下猜想的若干数值事实：6位APN函数集合仅限于14个CCZ等价类。