Generally speaking, chip encryption technology involves placing an encryption and authentication chip on a PCB board, along with some simple circuitry, and loading an anti-theft algorithm to prevent the theft of information within the chip. When the encryption lock bit is locked during programming, a regular programmer cannot directly read the program inside the chip, thus providing protection.
Based on the different data encryption schemes and usage methods, encryption chips can be divided into two categories.
One type is the authentication-based encryption chip, whose advantages include secure encryption chip service platform, unified algorithms, and ease of use. Its disadvantages include a lower overall security level, weaker protection for the main control MCU, and proven vulnerabilities. The encryption chip can be easily cracked by attacking the MCU.
Another approach is to use an encryption chip within the intelligent chip service platform, employing an algorithm and data porting scheme. Part of the main control MCU's program and data are ported to the encryption chip for execution. During operation, the encryption chip performs functions missing from the MCU while simultaneously ensuring the absolute security of certain parts of the program, thus guaranteeing the overall security of the product.
What are some chip encryption technologies?
1. Grinding: Use fine sandpaper to grind away the model number and specifications on the chip. This is more useful for less common chips. For common chips, you only need to guess the general function and check the pin grounding and power supply connections to easily identify the actual chip.
2. Sealing: After solidification, the adhesive, resembling stone (for bonding steel or ceramics), completely covers all components on the PCB. Simultaneously, the internal traces are disrupted and twisted together with thin enameled wire, making it difficult to reconnect jumpers during adhesive removal. Precautions: The adhesive must not be corrosive, and the temperature rise in the sealed area should be minimal.
3. Port a portion of the program from the CPU or software to the encryption chip, making the program incomplete and requiring the encryption chip to function correctly. Provides DES and 3DES encryption/decryption functions.
4. Bare die; you can't tell the model, specifications, or wiring. The chip's function is also difficult to guess. Then, other components, such as small ICs or resistors, are placed inside the black adhesive.
5. Connecting a resistor of 60 ohms or more in series on a signal line with a low current (so that the continuity setting on the multimeter doesn't make a sound) will greatly increase the difficulty of testing the wiring relationship with the multimeter.
5. Connecting a resistor of 60 ohms or more in series on the power line with a relatively small current (so that the digital multimeter does not make a sound when the current is interrupted) will greatly reduce the inconvenience when using the digital multimeter to test the connection.
6. Use some small components with obscure codes in signal processing, such as small surface-mount capacitors, TO-XX diodes, and small chips with three to six pins, to increase the difficulty of finding the true function of the components.
7. Address or data line crossings (except for RAM, corresponding crossings need to be performed in the software) make it difficult to apply the same principles to side connection relationships, increasing the difficulty of operation.
8. The PCB uses buried vias and blind vias to hide the vias inside the board. This method is more expensive and is suitable for high-end products.
9. Other specialized accessories are used, such as customized LCD screens, customized transformers, SIM cards, encrypted hard drives, etc.
