Microcontroller Decryption Technology

Microcontroller Decryption is a consistently improving technology and microcontroller designer always scratch their head and try to figure out if there is any new way to prevent the decryption method. There is one way to convert the security fuse become part of microcontroller storage system, or prohibit the read and write, decrypt microcontroller if the security fuse has been settled. Traditional fuse is very close to main microcontroller storage area or maybe just share the control circuit directly with it. Since the wafer manufacturer use same technology and workmanship of microcontroller to produce the fuse, it is quite difficult to locate and decrypt microcontroller. Un-invasive microcontroller decryption is still available but need time to locate them so as semi-invasive decryption. For sure it will take cracker more time to locate the security fuse or control circuit which in charge of the part of monitoring, even this part can be fulfilled automatically. Invasive microcontroller decryption could be extremely difficult since it will be operated by hand and cost much more than the budget.

 

More advanced method is control the external visiting against data in the microcontroller storage area. This function can be executed when provide the power supply to lock the specific area address information, and view it as the security fuse. Or control the visiting from microcontroller decryption through password. Such as MSP430F112 from TEXAS instrument, the read-back operation can be done only after the 32bits of password can be input correctly. Only after the password has been input correctly then the operation can be proceed when decrypt microcontroller. Although this method seems more effective than other microcontroller but it can still be decrypted by using invasive decryption. And the flaws of this microcontroller can be decrypted through low cost un-invasive attack method such as time sequence analysis and power consumption analysis. If the state of security fuse is part of the microcontroller after being power on, it will leave opportunity for the cracker to use power supply noise for decrypt microcontroller.


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