Abstract: Various types of mobile platforms such as smart phones,tablet computer,and embedded system have rapid popularized and penetrated into all aspects of life and work．The mobile platform application brings rich,colorful and convenient life,also brings many new security problems．Identity anthentication and access authentication are the first barrier protecting mobile platform．Combining with the muti-touch technology,gravity sensing technology and graphical password,several authentication schemes were designed and developed for mobile platforms,including drawing curve anthentication scheme,image choose authentication scheme,multiple point authentication scheme and gravity sensing authentication scheme．The setting and verification of password are convinient using the designed schemes,which can produce larger key space through a simple operation and possess higher security than simple password anthentication.

Key words: Mobile platform,Identity authentication,Graphical passwords,Multi-touch,Gravity sensing