Application of a Formal Specification Language in the Development of the "Mobile FeliCa" IC Chip Firmware for Embedding in Mobile Phone

We applied the formal specification language VDM++ in the development of firmware of the “Mobile FeliCa” IC chip. As an outcome, we have achieved successful results and confirmed its effectiveness. The objectives of applying a formal method were as follows: (1) Description of rigorous specifications; (2) Development and application of a scheme and processes for specification development, firmware implementation and testing; (3) Enhancing the quality of deliverables at the upper stream of development process; (4) Testing thoroughly with formal specifications for whole software development processes; (5) Improvement of communication between engineers. 1 Outline of Project “FeliCa” is a contactless IC card technology widely used in Japan, developed and promoted by Sony Corporation. This FeliCa technology is utilized in the Mobile FeliCa IC chip which is embedded in a mobile phone. Mobile phones embedded with the FeliCa IC chip are known as “Osaifu Keitai” (means of mobile wallet) by NTT DoCoMo, Inc., and today those chips are embedded in over 50 million mobile phones which can be used as electric money, train tickets, identifications, door keys and so on. The mobile FeliCa system is comprised of mobile phones with the FeliCa IC chip, FeliCa servers connected to the mobile telecom network and FeliCa reader/writers. The mobile FeliCa system is shown in Figure 1. The characteristics of the Mobile FeliCa IC chip firmware are as follows: • Contains the secure file system and the communications protocol, which are the basis of the FeliCa technology; (El e c t r i c Mo n e y , Tr a i n Ti c k e t s , Id e n t i f i c a t i o n s , Do o r Ke y s , e t c . ) A n t e n n a A n t e n n a C l i e n t S y s t e m O p e r a t i o n a l N e t w o r k S e r v e r S y s t e m (N e t w o r k De p o s i t S e r v i c e s , e t c . ) Th e In t e r n e t Mo b i l e P h o n e Mi d d l e w a r e A p p l i c a t i o n Mo b i l e F e l i C a IC C h i p Mi d d l e w a r e A p p l i c a t i o n Ta m p e r R e s i s t a n t De v i c e C o n t a i n i n g Ke y s Mi d d l e w a r e A p p l i c a t i o n F e l i C a R e a d e r W r i t e r Fig. 1 Mobile FeliCa System