The Value Added Tax (AVT) anti-fake and control system, which is one of the main parts of the National Golden Taxes Project, is developed for VAT supervising and preventing the tricks in VAT invoice that lead to the tax evasion. A special data encryption mechanism is adopted in the system to implement the detection and countercheck of the fake invoices. The “black box”，which is the combination of microprocessor, DSP, smart IC card and flash memory, can realize taxation supervising from the sources of the tax and invoice. The invention and popularization of the system greatly benefit the taxation and government finance. The system has been contributive to the national tax supervision.

As an especial commercial encryption application, the system must work properly under all kinds of complex condition. To obtain high security, the system adopts a systematic security design technique according to the secure model for the system in respect of the kernel hardware, encryption algorithm, key management, device connection channels protection, running conditions, information recording and auditing, system function and system management. The system now is proved safe enough to defend the attacks from the criminal organizations as well as any persons from the tax departments.