Software protection idea

[artem]

emule ds1961s

The idea is very simple use some volatile memory with low power consumption (coudl be external RAM or mcu internal ram for power down mode) and make protective tamper detection circuits . When anyone try to open the case the content of ram is to be destroyed either by power off. RAM should contain information the design is to be authenticated to before starting execution .

RAM could be preloaded with secret communication program to load encryption key
after device assembling.

Due to low power consumption it is possible to use litium battery for backup purposes .

The key be used for encryption of configuration memory . Each product configuration must be encrypted by using key in the ram . Or if your micro supports code in ram you can decrypt software on fly each time start up is happened. Each device must be encoded with its unique encryption key .

 

[Cortex]

For Ram it a bad idea
because we can SPY it and Emule it
and for Mcu
there a loot of ways to read Protected Pic/Mcus

 

[AVR_Luciano]

Hi!

When anyone try to open the case the content of ram is to be destroyed.....

......with 50 grams of C4 explosive.

Are you working for Q Branch?

Seriously, the anti-tamper circuit will work for the first enclosure, but once you open it you
will see how it is built and therefore you will know how to open the second enclosure without
triggering the anti-tamper circuit.

Best regards,

Luciano
(Q Branch part-time consultant)

 

[artem]

I am not talking about the implementation of tamper . Same idea is present for fpga design with preloaded ram without ip stored on eeprom .

 

[AVR_Luciano]

In case of a MCU with external RAM (battery backed-up RAM),
how do you prevent what was mentioned in the reply of the user Cortex?
(Make a copy of the MCU and make a copy of the external RAM).

 

[artem]

First of all you can have both internal sram and external SRAM. The location for wencryption keys in SRAM must never be initialized at mcu reset . MCU also must not be powered down - could go into power sleep mode and wait for interrupt . If such interrupt will be happened from tamper circuit - mcu wake up muct be done followed by sram location erase .
Usage of internal sram is preferred.

 

[digitalmg]

Product to secure,Secure Microprocessor Chip from Maxim **broken link removed**
use external battery backed-up RAM
or iButton **broken link removed**
DS1961S and DS1963S use SHA (Secure Hash Algorithm)