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Microcontroller decryption is generally hardware related. Only a few traditional 51 microcontrollers can be read down directly by the programmer after cracking. Now many microcontrollers (including the enhanced 51 microcontroller) are using a physical process to encrypt the program \"hidden\" in the chip, the general treatment of this kind of microcontroller only open the chip with professional instruments to crack.
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Single-chip decryption is a very loaded thing, first of all, you need to oxidize the surface of the chip package and decrypt it with professional equipment.
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The first is to dissolve the chip package completely, exposing the metal wiring. The chip needs to be attached to the test fixture and operated with the help of a binding table.
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The second is to remove only the plastic packaging on top of the silicon core. In addition to the need to have a certain amount of knowledge and necessary skills of the attacker, it also requires personal wisdom and patience, but the operation is relatively convenient and completely operated in the family.
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The plastic on the chip can be peeled off with a knife, and the epoxy around the chip can be corroded away with concentrated nitric acid. The hot concentrated nitric acid will dissolve the chip package without affecting the chip and the wiring. This process is generally performed in very dry conditions, as the presence of water may erode the exposed aluminum wire connections (which may cause decryption failure). The chip is then cleaned with acetone to remove residual nitric acid in an ultrasonic tank and soaked.
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The final step is to find the location of the protective fuse and expose the protective fuse to UV light. For this type of microcontroller, microprobe technology is generally used to read the memory contents. After the chip package is opened, the data bus connecting the memory to the rest of the circuit can be easily found by placing the chip under a microscope. For some reason, the chip lock bit does not lock access to memory in programming mode. This flaw can be exploited by placing the probe on top of the data line and reading all the desired data. In programming mode, restart the reading process and connect the probe to another data line to read all the information in the program and data memory.