RFC: generating a header using the linker (CRC calculation)

[Ulf Samuelsson]

> 15 feb. 2023 kl. 23:12 skrev Paul Koning <paulkoning@comcast.net>:
> 
> 
> 
>> On Feb 15, 2023, at 5:08 PM, Ulf Samuelsson <binutils@emagii.com> wrote:
>> 
>> The AUTOSARS says CRC-64 ECMA.
>> It is also popular in Linux.
>> I have not seen anyone using SHA algorithms or MD5 in any embedded project I have worked with to verify the flash contents.
> 
> I'm not sure I have on anything I worked on, but it's how one would do cryptographic integrity (for example, signed code) when tamper-resistance is required.  It's more likely to show up as a signature on an update kit, which would prevent the installation of false updates.
> 

Since the CRC check is done on code already flashed into the chip. we are way past the point of installation. 
The latest project I worked on would first download the installation package into an embedded linux system. This would download images to the embedded microcontroller, and all such verifications would be done in linux. 

Best Regards
Ulf Samuelsson

>> My proposed implementation would make it easy to use the ISO or ECMA variants, but also allow a user defined polynom.
> 
> That's certainly useful, so long as it is understood that CRC provides no protection whatsoever against deliberate tampering.
> 
>    paul
>