Beijing shouxi zhixin company conducted lots of experiment about a security fuse to
control access to information on MCU.
Software implementation means that a password is stored in the memory or a certain
memory location is assigned as a security fuse. For example, in the Motorola MC68HC908
family, password protection is used, and in the Motorola MC68HC705B family, the security
fuse is located in the first byte of the data EEPROM memory. For Motorola MC68HC705B,
we can get the programe and source code.
In hardware implementation, security fuses are physically located on the chip die.
This could mean a separate memory cell located next to the main memory array, or even
far from it. For example, this is the case for all Microchip PIC MCU and Atmel AVR MCU.
We can provide Microchip PIC MCU and Atmel AVR MCU reverse and decryption service.
In both cases, the security is not very high as the fuses can be easily found and
disabled by one or another method.
Meantime, some methods require very expensive equipment and even if the people who want to copy MCU firmware knows where the fuse is, he will not be able to reset it.
www.mcureverse.com provides more information about ic reverse knowledge.