Professor Cheung Yiu-ming demonstrates using the world’s first “lip motion password” technology, which can provide double security in identity authentication.


浸大計算機科學系張曉明教授示範使用全球首創的「唇語密碼」技術,雙重驗證使用者的身份,提升安全度。

A diagram shows the basic concept of lip motion password and how it works.


「唇語密碼」技術的基本架構。

Date: 06 Mar 2017 (Monday)

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HKBU scholar invents world’s first “lip password”: A patented double security system for identity authentication

浸大研發全球首創「唇語密碼」﹕雙重安全身份認證系統

The use of biometric data such as fingerprints to unlock mobile devices and verify identity at immigration and customs counters are used around the world. Despite its wide application, one cannot change the scan of their fingerprint. Once the scan is stolen or hacked, the owner can’t change his/her fingerprints and has to look for another identity security system. In view of this, a scholar of HKBU has invented a new technology entitled “lip motion password” (lip password) which utilises a person’s lip motions to create a password. This system verifies a person’s identity by simultaneously matching the password content with the underlying behavioural characteristics of lip movement. Nobody can mimic a user’s lip movement when uttering the password which can be changed at any time. This novel technology, the first in the world and has been granted a US patent in 2015, is expected to be used in financial transaction authentication.

HKBU’s Department of Computer Science Professor Cheung Yiu-ming in charge of the research said the new technique has a number of advantages over conventional security access control methods: 1) The dynamic characteristics of lip motions are resistant to mimicry, so a lip password can be used singly for speaker verification, as it is able to detect and reject a wrong password uttered by the user or the correct password spoken by an imposter; 2) Verification based on a combination of lip motions and password content ensures that access control is doubly secure; 3) Compared with traditional voice-based authentication, the acquisition and analysis of lip movements is less susceptible to background noise and distance, moreover, it can even be used by a speech-impaired person; 4) A user can reset the lip password in a timely manner to strengthen security; 5) There is no language boundary, in other words, a person from any country can use this lip password verification system. 

Professor Cheung said: “The same password spoken by two persons is different and a learning system can distinguish them.” The study adopted a computational learning model which extracts the visual features of lip shape, texture and movement to characterise lip sequence. Samples of lip sequence are collected and analysed to train the models and determine the threshold of accepting and rejecting a spoken password.

The potential application of this new patented technology includes, but is not limited to, financial transaction authentication including electronic payment using mobile devices, transactions at ATM machines, and credit card user passwords. It can also be applied to enhance the security access control system currently used in entrances of companies or private premises.

In addition, lip password can be used together with other biometrics to enhance the security level of systems. For instance, lip password can be combined with face recognition, whereby the problem of spoofing face recognition with 3D masks in personal identity verification would be solved.

生物特徵識別技術如手機指紋解鎖、出入境時的指紋掃描等現今已廣泛使用。然而,指紋特徵一旦遭人竊取或盜用,用戶無法更改特徵並不能繼續安全使用指紋。浸大學者研發出一項嶄新的「唇語密碼」(簡稱「唇碼」)技術,此單一識別方式同時結合了唇部動作的生物特徵及可更改的密碼內容以提供雙重驗證,提高系統的安全性。這項全球首創的技術已於2015年取得美國專利,預計可應用於財務交易驗證。

率領此研究的浸大計算機科學系張曉明教授表示,相對於傳統的保安存取控制方法,唇碼新技術的優點包括:(一)每個人的嘴唇動作特徵不一樣,難於模仿,因此用戶說出錯誤密碼,或者即使知道密碼的人嘗試頂替用戶說出密碼,亦無法通過系統驗證。(二)唇碼技術需同時驗證嘴唇動作和密碼內容,雙重驗證,安全度更高。(三)與需用聲音確認身份的驗證系統比較,使用唇碼時無需發聲,因此不受背景雜音或距離影響,言語障礙人士也可使用。(四)用家可隨時重設唇碼以加強安全度。(五)設定唇碼時沒有語言限制,任何語言,包括方言,均可使用。

張曉明教授說:「兩個人即使說同一句話,嘴唇的動作特徵一般也是不一樣的,可用人工智能的方法來區分。」研究使用了機器學習中一個學習模型,從嘴唇圖像序列中提取形狀、質地、動作等視覺特徵,通過訓練建立模型並確定閾值(臨界值)來決定接受或拒絕密碼。

新專利技術可應用到財務交易驗證,如流動通訊的電子交易、以自動提款機進行交易、信用卡密碼驗證等;亦可應用到企業或私人用地的入口保安系統。

此外,唇碼也可結合其他生物特徵識別技術一起使用,如結合「臉部識別系統」,有助解決利用三維面具仿製個人身份的電子詐騙問題,以提升保安度。