What does stk in the mobile phone mean?

STK is the abbreviation of SIM Toolkit, namely "User Identification Application Development Tool". It contains a set of instructions for the interaction between the mobile phone and the SIM card, so that the SIM card can run small applications in the card and realize the purpose of value-added services. It is called applet because the application in STK card is not large and the function is simple and easy to use due to the space limitation of SIM card. At present, there are two mainstream STK cards in the market: 16K and 32K. 64K cards are also actively promoted in the market.

The difference between STK card and ordinary SIM card is that the application program is solidified in STK card. Provide users with a text menu interface through software activation. This kind of text menu interface allows users to realize information retrieval and even transaction through simple key operation. For example, if the end user wants to query the weather forecast, in the absence of STK value-added service, the user needs to manually edit the short message "TQ 0 10" and then send the short message to the 168 service platform. In this way, users need to remember that "TQ" is the command code of weather forecast and the service platform number of 168. In fact, there are many instruction codes, such as "GP" for stock inquiry and "HF" for telephone inquiry. Therefore, it is unrealistic and inconvenient for users to remember all the command codes. STK provides menu prompts such as "weather forecast" to the user through the solidified program in the card, and the user can find the weather only by inputting the long-distance area code of the area he wants to query. Therefore, users do not need to memorize command codes and service platform numbers, and the purpose of convenience for users is achieved.

The realization of STK value-added service is based on GSM short message. Therefore, as long as it is covered by GSM network, it can provide a wide range of text information services; Moreover, short messages are cheap, and they are charged only if they are sent successfully, excluding roaming charges; Based on the above reasons, the number of STK card users has surged and the business model has become increasingly mature.

The platform of STK card is not unified, which makes the STK programs developed by various manufacturers incompatible with each other. In this way, each card vendor's application can only run on its own specific platform. Thereby bringing great inconvenience to the operator. JAVA technology applied to STK card is Java card. The technical problems of Java card are not discussed in this paper, because there are a lot of materials in this field. This paper only briefly introduces the implementation and characteristics of STK in Qiqi Company.

First of all, the STK card of Qiqi Company fully complies with a series of specifications such as GSM111,GSM 1 14 and GSM 03.08. Therefore, its usability is no different from that of other companies, and it can completely meet the requirements of different operators. Secondly, Qiqi's STK card is similar to JAVA card, and it is also realized by having an interpreter in SIM card to interpret and execute bytecode. The difference with JAVA card is that the interpreter is independently developed, and bytecode is also a proprietary format of Qiqi Company. The advantage of Qiqi's STK card solution is that the program design is optimized for the application of SIM card, so the interpreter's execution efficiency and occupied space are obviously better than that of JAVA card. Based on the above reasons, the STK card program of Qiqi Company runs fast, and can realize more applications on cards with the same capacity. Thirdly, the STK card of Qiqi Company can be selectively combined with PKI, and the signature can be verified by the R.S.A algorithm implemented in the card. So that using mobile phones to engage in mobile business activities is no longer an armchair strategist.

The above is just a brief overview of the development of Qiqi STK card, aiming at giving readers a preliminary understanding of Qiqi STK card solution.