PCB Technical - Learn to decrypt by understanding PCB chip encryption

Learn to decrypt by understanding PCB chip encryption

1. Grind the chip, use fine sandpaper to grind off the model number on the chip. For partial gate chips, it is more useful. For commonly used chips, thieves only need to guess a general function, check which pins are grounded, and it is easy to connect to the power source to compare the real chip;

2. Sealing glue, use the kind of glue that is like a stone after solidification (such as the kind of steel or ceramic) to cover all the PCB circuit board and the components on it. There can also be deliberately made five or six flying wires (a thin enameled wire is best) twisted together, so that the thief will inevitably break the flying wires during the process of removing the glue and do not know how to connect. It should be noted that the glue cannot be corrosive, and the enclosed area does not generate much heat.

3. Using a dedicated encryption chip, such as ATMEL AT88SC153, is only a few dollars. As long as the software cannot be disassembled, the thief cannot copy all the signals even if they intercept all the signals with a logic analyzer.

4. Use unbreakable chips, such as EPLD’s EPM7128 or higher, ACTEL’s CPLD, etc., but the cost is higher (over one hundred yuan), which is not applicable to small products;

5. Using MASK IC, generally speaking, MASK IC is much harder to crack than programmable chips, which requires a lot of batches. MASK is not only to MCU, but also includes ROM, FPGA and other dedicated chips.

6. Using bare chips, the thieves can't see the model and don't know the wiring. But the function of the chip should not be too easy to guess, it is best to put other things in the group of vinyl, such as small ICs, resistors, etc.;

7. Connect a resistance of 60 ohms or more in series on the signal line with a small current (to make the on-off gear of the multimeter not sound), so that the thief will increase a lot of trouble when using the multimeter to measure the connection relationship.

8. Use more small components without words (or only some codes) to participate in signal processing, such as small chip capacitors, TO-XX diodes, triodes, small chips with three to six pins, etc., and want to find out its true The face is still a bit troublesome.

9. Cross some address and data lines (except RAM, the software needs to be crossed correspondingly), so that those thieves can't be lazy by analogy when testing the connection relationship.

10. PCB adopts buried via and blind via technology, so that the via is hidden in the board. This method is costly and is only suitable for high-end PCB products.

11. Use other special accessories, such as customized LCD screens, customized transformers, SIM cards, encrypted disks, etc.

12. Apply for a patent. In view of the poor environment of intellectual property protection, the most preferred method abroad is the last one for us.

PCB factories should master PCB chip encryption and learn how to decrypt, so as to improve the quality of PCB production, and regularly train employees to improve their mastery of professional knowledge.