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Vernita Brevard

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What is the IC unlock ? Remove chip packaging The first step in an intrusive attack is to uncover the chip package (sometimes referred to as “uncovering”, “uncovering”, “Decay”, encapsulation). There are two ways to achieve this goal: The first is to completely dissolve the chip package and expose the metal connection. The second one is to remove only the plastic package on the silicon core. The first method needs to bind the chip to the test fixture and operate with the help of the binding table; the second method needs not only the knowledge and necessary skills of the IC unlock, but also the wisdom and patience of the individual, but it is relatively convenient to operate and operate completely in the family. The plastic on the chip can be uncovered with a knife, and the epoxy resin around the chip can be corroded by concentrated nitric acid. Hot concentrated nitric acid will dissolve the chip package without affecting the chip and connection. This process is usually carried out in very dry conditions, because the presence of water may erode exposed aluminum wire connections (which may cause decryption failure). Cleaning chip 1. The chip is then cleaned with acetone to remove residual nitric acid and soaked in the ultrasonic pool. 2. Find the position of the protective fuse and destroy it. 3. The last step is to find the position of the protective fuse and expose the protective fuse to ultraviolet light. Usually, a microscope with at least 100 magnification is used to trace the protection fuse from the connection of the programmable voltage input foot. In the absence of a microscope, a simple search is performed by exposing different parts of the chip to ultraviolet light and observing the results. Operating with opaque paper overlay chip to protect program memory from ultraviolet erasure. Exposing the fuse to ultraviolet light for 5 to 10 minutes can destroy the protective effect of the protective position. After that, the content of program memory can be read directly by using a simple programmer. Ultraviolet reset protection circuit is not feasible for single chip microprocessors which use protective layer to protect the EEPROM units. For this type of micro controller, micro probe technology is generally used to read the memory content. After the chip package is opened, the data bus connecting the memory to other parts of the circuit can be easily found by placing the chip under the microscope. For some reason, the chip lock bit does not lock access to memory in programming mode. Using this defect, the probe can be placed on the data line to read all the desired data. In programming mode, all information in program and data storage can be read out by restarting the reading process and connecting the probe to another data line. Destruction of protective fuses by means of microscope and laser cutting machine Another possible attack is to find protective fuses by means of microscopes and laser cutting machines, so as to find all the signal lines associated with this part of the circuit. Because of the design flaws, the whole protection function can be prohibited by cutting off a signal line (or cutting off the whole encryption circuit) from the protection fuse to other circuits or connecting 1-3 gold wires (commonly called FIB: focused beam). Thus, the content of program memory can be read directly by using a simple programmer. Although most ordinary the MCU controllers have the function of protecting the code in the MCU controller by fuse programming, they often fail to provide pertinent preventive measures and the security level is low because the general low-grade single-chip micro controllers are not located in the production of security products. In addition, The MCU  has a wide range of applications, large sales, frequent commissioned processing and technology transfer between manufacturers, and many technical data leakage, which makes it easier to use the design loopholes of such chips and manufacturers'test interfaces, and to read the internal program of The MCU  by modifying intrusive or non-intrusive attack means such as fuse protection position.

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