Could be used lockbox to protect program cod in BF50xF?
There are few techniques, but unfortunately they may not be as sophisticated as the level of security provided by Lockbox.
You can get some ideas here:
I could find a good discussion in another thread, which provides more information about it. Hope that will be useful in general.
BF50xF processor (i.e. processor with internal parallel FLASH) provides some level of protection through flash die integration, as the flash or EBIU pins are not exposed externally.
You can implement some kind of encryption for the code. The OTP register in flash can be used to store an encryption key, or you might want to store the encryption/decryption key somewhere random in flash.
The 128-bit user programmable OTP cells (128 bits total) and the 64-bit unique device number allow the designer to implement some level of protection, but certainly not at the level of security provided by Lockbox.
For example, to prevent cloning, you can bind your code to the unique device number in flash. When you initialize your application, you compare the unique device number in flash against the same value stored in your code. If they do not match, the application halts. Though it should not be implemented as simple as this, but this method requires following point to consider:
Every flash image has to be different. Specifically, it has to include the unique number of the flash it will be stored in. This can be done at flash programming time. In other words, when you program the flash, the flash programmer reads the unique device number from flash, patches the flash image with that unique device number and then programs the patched image into flash.
A hacker who steals the flash image and attempts to clone the product will encounter some difficulty. Specifically, when the flash image is cloned and placed in a different flash device, the unique device number in the new flash device will not match the unique device number stored in the flash image. So the application will halt. Of course, this only provides a moderate level of protection against unsophisticated hackers.
If your customer is concerned about IP protection, then the flash protection features don't really provide much help. However, as mentioned earlier BF50x offers some level of inherent security since the flash is internal to the product and neither the flash signals nor the EBIU signals come out to package pins. So a hacker will have to execute code on the Blackfin in order to steal the flash image; of course, which is not impossible. But you can decide not to bring out the JTAG signals in the production PCBs and use Epoxy technique to cover JTAG pins.
Hope it helps,
The BF50x does not have Lockbox. This is only available on the BF51x, BF52x and BF54x families.
May be you know other technique to protect program cod in BF50xF from unwanted reading out?
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