Quentin Schulz <foss+uboot@0leil.net> says:

While historically signature verification is mostly done for FIT such
FIT_SIGNATURE dependency for signature algorithm makes sense, it isn't
the only kind of file we can verify signatures of. It can also be done
manually with rsa_verify_hash() with an embedded public key.

Considering the impacted code is guarded by RSA_VERIFY, let's make the
symbol depend on that otherwise selecting it without RSA_VERIFY won't do
anything. The FIT_SIGNATURE dependency wasn't also enough before as it
only implied RSA_VERIFY.

Then, simply relocate the RSA SSA PSS padding with the other RSA symbols
in lib/rsa instead of in boot/ and rename it to remove the mention to
FIT.

Finally, add the PSS padding wherever PKCS1.5 padding is specified as
one or the other can be used.

Link: https://lore.kernel.org/r/20251031-rsa-pss-always-v2-0-a29184ea064d@cherry.de

This renames FIT_RSASSA_PSS symbols to drop the FIT_ prefix to avoid
potential confusion since there's nothing FIT specific to those symbols.

It also isn't really related to booting, so boot/Kconfig is an odd place
for them to live. Since they make sense only in relation with RSA,
simply move them to lib/rsa where it makes more sense for them to
reside.

Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>

Signed-off-by: Quentin Schulz <quentin.schulz@cherry.de>

Tighten up symbol dependencies in a number of places.  Ensure that a SPL
specific option has at least a direct dependency on SPL.  In places
where it's clear that we depend on something more specific, use that
dependency instead.  This means in a very small number of places we can
drop redundant dependencies.

Reported-by: Pali Rohár <pali@kernel.org>
Signed-off-by: Tom Rini <trini@konsulko.com>

This commit adds the option SPL_RSA_VERIFY_WITH_PKEY.

Reviewed-by: Simon Glass <sjg@chromium.org>
Signed-off-by: Philippe Reynes <philippe.reynes@softathome.com>

ACRY is designed to accelerate ECC/RSA digital signature
generation and verification.

Signed-off-by: Chia-Wei Wang <chiawei_wang@aspeedtech.com>

The CAAM on IMX7ULP doesn't support public key hardware acceleration
(PKHA), as in other NXP parts. Disable RSA_FREESCALE_EXP for IMX7ULP
too.

Fixed: f4e9ff7135 ("Kconfig: Don't use RSA_FREESCALE_EXP on IMX")
Signed-off-by: Ricardo Salveti <ricardo@foundries.io>
Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>

SPL_RSA_VERIFY requires SPL_RSA to be enabled. Add correct
dependency.

Signed-off-by: Oleksandr Suvorov <oleksandr.suvorov@foundries.io>

In the current implementation of FIT_SIGNATURE, five parameters for
a RSA public key are required while only two of them are essential.
(See rsa-mod-exp.h and uImage.FIT/signature.txt)
This is a result of considering relatively limited computer power
and resources on embedded systems, while such a assumption may not
be quite practical for other use cases.

In this patch, added is a function, rsa_gen_key_prop(), which will
generate additional parameters for other uses, in particular
UEFI secure boot, on the fly.

Note: the current code uses some "big number" routines from BearSSL
for the calculation.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>

In the next couple of commits, under new CONFIG_RSA_VERIFY_WITH_PKEY,
rsa_verify() will be extended to be able to perform RSA decryption without
additional RSA key properties from FIT image, i.e. rr and n0inv.

Signed-off-by: AKASHI Takahiro <takahiro.akashi@linaro.org>
Reviewed-by: Simon Glass <sjg@chromium.org>