Re: [RFC 2/4] Add rsa support

[Jean-Christophe PLAGNIOL-VILLARD <plagnioj@jcrosoft.com>]

On 13:09 Tue 17 Mar     , Jan Lübbe wrote:
> Hi Jean-Christophe,
> 
> On Di, 2015-03-17 at 11:48 +0100, Jean-Christophe PLAGNIOL-VILLARD wrote:
> > > Could you explain your image format in a bit more detail? How your
> > > intend to defend against a mix-and-match attack?
> > 
> > One of the format we are using can only be one configure signed or/and
> > encrypted so no mix-and-match attack
> 
> Sorry, it's still not clear to me. Do you mean you would use FIT in that
> case (it supports signed configurations)? Or do you mean that you are
> using several formats, one of which uses signed/encrypted configurations
> of kernel/initramfs/dt?
yes sevral format FIT is just one of them
> 
> I want to understand how your image formats would be used in the larger
> context of a BSP or distribution. Please describe which image formats
> you want to support (in addition to FIT). How are they structured? How
> are they generated? Are they already supported by other software? 
Today we use a bpk formoat

in bpk format you can store different data for each hw_id, each data have a
specific type.

we add a new type for the signature.

we do a sha512 of the other data of one hw_id and signed it with a rsa4096
we use 1 unique rsa key per HW_ID

as soon as one of the file of a specific hw_id is open we check the signature

The code is no public yet but this is handled at FS level

and we allow only to open data that have been verified or decrypted if we use
AES

Best Regards,
J.

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