[PATCH v6 07/28] hash: integrate hash on mbedtls

[Ilias Apalodimas]

Hi Raymond,

On Tue, 3 Sept 2024 at 18:54, Raymond Mao <raymond.mao at linaro.org> wrote:
>
> Hi Ilias,
>
> On Fri, 30 Aug 2024 at 05:37, Ilias Apalodimas <ilias.apalodimas at linaro.org> wrote:
>>
>> Hi Simon,
>>
>> On Thu, 29 Aug 2024 at 18:01, Simon Glass <sjg at chromium.org> wrote:
>> >
>> > Hi Raymond,
>> >
>> > On Fri, 16 Aug 2024 at 15:47, Raymond Mao <raymond.mao at linaro.org> wrote:
>> > >
>> > > Integrate common/hash.c on the hash shim layer so that hash APIs
>> > > from mbedtls can be leveraged by boot/image and efi_loader.
>> > >
>> > > Signed-off-by: Raymond Mao <raymond.mao at linaro.org>
>> > > ---
>> > > Changes in v2
>> > > - Use the original head files instead of creating new ones.
>> > > Changes in v3
>> > > - Add handle checkers for malloc.
>> > > Changes in v4
>> > > - None.
>> > > Changes in v5
>> > > - Add __maybe_unused to solve linker errors in some platforms.
>> > > - replace malloc with calloc.
>> > > Changes in v6
>> > > - None.
>> > >
>> > >  common/hash.c | 146 ++++++++++++++++++++++++++++++++++++++++++++++++++
>> > >  1 file changed, 146 insertions(+)
>> >
>> > I am not seeing the benefit of replacing U-Boot's hashing algorithms.
>> > They work well and don't change. Also it seems to be making the code a
>> > lot uglier, with an uncertain timeline for clean-up.
>>
>> A lot uglier where? It adds a few wrappers that fit into the current
>> design and callbacks.
>> I don't think what you are asking is possible. To do assymetric
>> crypto, signatures  etc -- and in the future add TLS support in wget
>> mbedTLS relies on its internal hashing functions for the cipher suites
>> it supports. So what you are asking would just make the code even
>> larger. Raymond can you please double check?
>>
> Digest is the basic library of MbedTLS, I don't believe we can disable it
> but only use the ones for certificates, unless MbedTLS makes changes
> to allow hooking external digest libraries -  as I mentioned in a previous reply,
> I don't think this is what MbedTLS wants.

There's a config option on config.h we could use to override shaXXX,
but given that mbedTLS can be used to add more hashing alogorithms, I
dont think we should do that

Cheers
/Ilias
>
> Regards,
> Raymond