中文摘要：

尽管用户的击键习惯随时间变化，但在后期几乎保持不变，单更新方法只更新模板中的中心点，而容忍半径保持不变，使击键认证算法在后期具有较高的漏报率。提出一种击键认证中用户模板的双更新方法，该方法同时更新模板中的中心点，及其容忍半径，能适应用户在前期击键习惯变化较大、而在后期基本不变的特点。实验证明，与单更新方法相比，该方法在后期能降低算法的漏报率。

英文摘要：

Although user＇ s typing rhythm changes in earlier stage, it nearly keeps stable later, the single update method can only update the central point in the template, but keep the tolerance radius unchanged, which might cause a higher FAR over time. This paper introduced a double update method for template in keystroke dynamics, which updated the central point and tolerance radius simultaneously. This method could adapt to both the large variations of user＇ s typing way in earlier stage, and the stable stage later. Experiments show that comparing to the single update method, the double one can decrease FAR in later stage.