線上簽名驗證

Abstract

近年來, 筆式輸入 (pen computing) 有越來越普遍的趨勢.大部分的個 人數位助理(PDA) 及筆記型電腦已將手寫輸入列為標準配備. 手寫輸入的普及, 隨之而來將導 致簽名驗證軟體的應運而生.本論文的目 的即在於發展一個簽名驗證系統. 我們使用普通的手寫板來輸入簽名. 所 得到的簽名樣本係由一連串的點所組成. 這些點包含了三個屬性 : X座標 、Y座標 以及輸入狀態（提筆或落筆）. DYNAMIC PROGRAMMING 對於字串的比對是個不錯的做法.特別是當兩串資料有相同的輸入順序而 僅有長度有差異時. 我們 使用 DYNAMIC PROGRAMMING 來計算簽名之間 的差異. 我們邀請了22人來測試我們的系統. 由於是線上處理, 測試者在簽完名後 即馬上驗證. 部份的測試者亦參與仿冒他人簽名的測試. 我們提供一些本 人的真跡簽名給模仿者進行仿冒. 絕大多數的仿冒簽名為系統所識破,但 仍有少數被系統誤判接受. 本論文將詳細探討我們 的系統及實驗結果. Pen computing is getting more and more popular, Most PDA's (Personal Digital Assistant) and quite a few notebook PC's have a pen as their standard input device. Where a pen is available, so should a signature verification software. In this thesis our goal is to develop a signature verification software. We take signatures from a plain pen. A signature is just a sequence of points, which consists of 3 attributes : x coordinate, y coordinate and pen condition (pen up or pen down). Dynamic programming provides a good mechanism for the matching of two strings , especially when the two strings have exactly same sequence and vary only in length. We make use of simple feature to compare the differences of signature. 22 people were invited to test our system. They registered their signature and then later tested if the system would accept their signature . Some of them also made forgery test. A signature of another person was purposely displayed for them to immitate. Some did succeed with their forgery, while most attempts failed. Details of our system and results of our tests are reported in this thesis.