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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>
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Migrate the x86_64 implementation of POLYVAL into lib/crypto/, wiring it
up to the POLYVAL library interface. This makes the POLYVAL library be
properly optimized on x86_64.
This drops the x86_64 optimizations of polyval in the crypto_shash API.
That's fine, since polyval will be removed from crypto_shash entirely
since it is unneeded there. But even if it comes back, the crypto_shash
API could just be implemented on top of the library API, as usual.
Adjust the names and prototypes of the assembly functions to align more
closely with the rest of the library code.
Also replace a movaps instruction with movups to remove the assumption
that the key struct is 16-byte aligned. Users can still align the key
if they want (and at least in this case, movups is just as fast as
movaps), but it's inconvenient to require it.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251109234726.638437-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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Migrate the arm64 implementation of POLYVAL into lib/crypto/, wiring it
up to the POLYVAL library interface. This makes the POLYVAL library be
properly optimized on arm64.
This drops the arm64 optimizations of polyval in the crypto_shash API.
That's fine, since polyval will be removed from crypto_shash entirely
since it is unneeded there. But even if it comes back, the crypto_shash
API could just be implemented on top of the library API, as usual.
Adjust the names and prototypes of the assembly functions to align more
closely with the rest of the library code.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251109234726.638437-5-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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Add support for POLYVAL to lib/crypto/.
This will replace the polyval crypto_shash algorithm and its use in the
hctr2 template, simplifying the code and reducing overhead.
Specifically, this commit introduces the POLYVAL library API and a
generic implementation of it. Later commits will migrate the existing
architecture-optimized implementations of POLYVAL into lib/crypto/ and
add a KUnit test suite.
I've also rewritten the generic implementation completely, using a more
modern approach instead of the traditional table-based approach. It's
now constant-time, requires no precomputation or dynamic memory
allocations, decreases the per-key memory usage from 4096 bytes to 16
bytes, and is faster than the old polyval-generic even on bulk data
reusing the same key (at least on x86_64, where I measured 15% faster).
We should do this for GHASH too, but for now just do it for POLYVAL.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Tested-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20251109234726.638437-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
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Use the Crypto API partial block handling.
The accelerated export format on x86/arm64 is easier to use so
switch the generic polyval algorithm to use that format instead.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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Add hardware accelerated version of POLYVAL for x86-64 CPUs with
PCLMULQDQ support.
This implementation is accelerated using PCLMULQDQ instructions to
perform the finite field computations. For added efficiency, 8 blocks
of the message are processed simultaneously by precomputing the first
8 powers of the key.
Schoolbook multiplication is used instead of Karatsuba multiplication
because it was found to be slightly faster on x86-64 machines.
Montgomery reduction must be used instead of Barrett reduction due to
the difference in modulus between POLYVAL's field and other finite
fields.
More information on POLYVAL can be found in the HCTR2 paper:
"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>
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Add support for POLYVAL, an ε-Δ-universal hash function similar to
GHASH. This patch only uses POLYVAL as a component to implement HCTR2
mode. It should be noted that POLYVAL was originally specified for use
in AES-GCM-SIV (RFC 8452), but the kernel does not currently support
this mode.
POLYVAL is implemented as an shash algorithm. The implementation is
modified from ghash-generic.c.
For more information on POLYVAL see:
Length-preserving encryption with HCTR2:
https://eprint.iacr.org/2021/1441.pdf
AES-GCM-SIV: Nonce Misuse-Resistant Authenticated Encryption:
https://datatracker.ietf.org/doc/html/rfc8452
Signed-off-by: Nathan Huckleberry <nhuck@google.com>
Reviewed-by: Eric Biggers <ebiggers@google.com>
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
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