There are many methods of chip decryption, which are roughly summarized as the method of software analysis, also called soft decryption method, and the method of decryption after the chip is opened, also called hard decryption.
The chip that can be soft decrypted generally needs to find the vulnerability of the chip design, and the program can be obtained by using the vulnerability, such as the timing error of the chip design of the AT89C51 before 97, and the encryption can be erased without erasing the memory.
At present, the mainstream decryption method is hard decryption.
Hard decryption means are also many, very complex, if you are not an electronic engineer, there is demand or contact professional people, the first silicon core in the industry reputation can be.