Currently, the standalone GHASH code is coupled with crypto_shash. This
has resulted in unnecessary complexity and overhead, as well as the code
being unavailable to library code such as the AES-GCM library. Like was
done with POLYVAL, it needs to find a new home in lib/crypto/.
GHASH and POLYVAL are closely related and can each be implemented in
terms of each other. Optimized code for one can be reused with the
other. But also since GHASH tends to be difficult to implement directly
due to its unnatural bit order, most modern GHASH implementations
(including the existing arm, arm64, powerpc, and x86 optimized GHASH
code, and the new generic GHASH code I'll be adding) actually
reinterpret the GHASH computation as an equivalent POLYVAL computation,
pre and post-processing the inputs and outputs to map to/from POLYVAL.
Given this close relationship, it makes sense to group the GHASH and
POLYVAL code together in the same module. This gives us a wide range of
options for implementing them, reusing code between the two and properly
utilizing whatever instructions each architecture provides.
Thus, GHASH support will be added to the library module that is
currently called "polyval". Rename it to an appropriate name:
"gf128hash". Rename files, options, functions, etc. where appropriate
to reflect the upcoming sharing with GHASH. (Note: polyval_kunit is not
renamed, as ghash_kunit will be added alongside it instead.)
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20260319061723.1140720-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
The "hash function" in hctr2 is fixed at POLYVAL; it can never vary.
Just use the POLYVAL library, which is much easier to use than the
crypto_shash API. It's faster, uses fixed-size structs, and never fails
(all the functions return void).
Note that this eliminates the only known user of the polyval support in
crypto_shash. A later commit will remove support for polyval from
crypto_shash, given that the library API is sufficient.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251109234726.638437-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
This reverts commit c4741b2305.
Crypto API self-tests no longer run at registration time and now
occur either at late_initcall or upon the first use.
Therefore the premise of the above commit no longer exists. Revert
it and subsequent additions of subsys_initcall and arch_initcall.
Note that lib/crypto calls will stay at subsys_initcall (or rather
downgraded from arch_initcall) because they may need to occur
before Crypto API registration.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Now that the shash algorithm type does not support nonzero alignmasks,
shash_alg::base.cra_alignmask is always 0, so OR-ing it into another
value is a no-op.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
As skcipher spawns may be of the type lskcipher, only the common
fields may be accessed. This was already the case but use the
correct helpers to make this more obvious.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
This patch does the final flag day conversion of all completion
functions which are now all contained in the Crypto API.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Add support for HCTR2 as a template. HCTR2 is a length-preserving
encryption mode that is efficient on processors with instructions to
accelerate AES and carryless multiplication, e.g. x86 processors with
AES-NI and CLMUL, and ARM processors with the ARMv8 Crypto Extensions.
As a length-preserving encryption mode, HCTR2 is suitable for
applications such as storage encryption where ciphertext expansion is
not possible, and thus authenticated encryption cannot be used.
Currently, such applications usually use XTS, or in some cases Adiantum.
XTS has the disadvantage that it is a narrow-block mode: a bitflip will
only change 16 bytes in the resulting ciphertext or plaintext. This
reveals more information to an attacker than necessary.
HCTR2 is a wide-block mode, so it provides a stronger security property:
a bitflip will change the entire message. HCTR2 is somewhat similar to
Adiantum, which is also a wide-block mode. However, HCTR2 is designed
to take advantage of existing crypto instructions, while Adiantum
targets devices without such hardware support. Adiantum is also
designed with longer messages in mind, while HCTR2 is designed to be
efficient even on short messages.
HCTR2 requires POLYVAL and XCTR as components. More information on
HCTR2 can be found here: "Length-preserving encryption with HCTR2":
https://eprint.iacr.org/2021/1441.pdf
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
