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
62e89de769