topic Re: kboot: don't use crc to verify an application image in Kinetis Microcontrollers

kboot: don't use crc to verify an application image

peterruesch — Thu, 07 Jul 2016 10:20:31 GMT

Hi,

currently crc32 is used to verify the flash content on boot. when building an secure product, this might be a showstopper.

have you considered using a signed hash?

Re: kboot: don't use crc to verify an application image

jeremyzhou — Fri, 08 Jul 2016 03:24:47 GMT

Hi Peter,

Thanks for your attention and focus the KBOOT, and I think it's a good suggestion.
Have a great day,
Ping

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Re: kboot: don't use crc to verify an application image

peterruesch — Fri, 08 Jul 2016 09:30:02 GMT

is my assumption wrong? I'm very new this whole crypto stuff but as far as I understood for now it's really not secure the judge an application valid based on a matching crc32?

I agree that this is better than nothing but it does not address the security aspect of the previous attempts of an aes128 encrypted binary or am I missing something?

Re: kboot: don't use crc to verify an application image

jeremyzhou — Mon, 11 Jul 2016 09:08:14 GMT

Hi Peter,

Thanks for your reply.

Actually, I was nfused with your question, as the CRC32 check feature is none with the AES-128 key.

I've also contacted with the Kboot team about your question, and they'd like to suggest that you'd better to explain the question again.
Have a great day,
Ping

Re: kboot: don't use crc to verify an application image

bobpaddock — Mon, 11 Jul 2016 12:08:02 GMT

The concern is that when building a secure product a CRC32 is easy to forge compared to a signed hash such as SHA-2/SHA-256/SHA-512. Note that SHA-1 is no longer recommended to be used by the Security Community.

AES-128 is meaningless as transfer security if what is being transferred has already been compromised.

Re: kboot: don't use crc to verify an application image

peterruesch — Tue, 12 Jul 2016 11:57:47 GMT

that iss exactly what I mean. But as I said: I'm very new to cryptography so you might have thought more far than me.

It seems to depend on how you define your chain of trust.