Many arm64 and x86_64 CPUs can compute two SHA-256 hashes in nearly the
same speed as one, if the instructions are interleaved. This is because
SHA-256 is serialized block-by-block, and two interleaved hashes take
much better advantage of the CPU's instruction-level parallelism.
Meanwhile, a very common use case for SHA-256 hashing in the Linux
kernel is dm-verity and fs-verity. Both use a Merkle tree that has a
fixed block size, usually 4096 bytes with an empty or 32-byte salt
prepended. Usually, many blocks need to be hashed at a time. This is
an ideal scenario for 2-way interleaved hashing.
To enable this optimization, add a new function sha256_finup_2x() to the
SHA-256 library API. It computes the hash of two equal-length messages,
starting from a common initial context.
For now it always falls back to sequential processing. Later patches
will wire up arm64 and x86_64 optimized implementations.
Note that the interleaving factor could in principle be higher than 2x.
However, that runs into many practical difficulties and CPU throughput
limitations. Thus, both the implementations I'm adding are 2x. In the
interest of using the simplest solution, the API matches that.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250915160819.140019-2-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
While the HMAC library functions support both incremental and one-shot
computation and both prepared and raw keys, the combination of raw key
+ incremental was missing. It turns out that several potential users of
the HMAC library functions (tpm2-sessions.c, smb2transport.c,
trusted_tpm1.c) want exactly that.
Therefore, add the missing functions hmac_sha*_init_usingrawkey().
Implement them in an optimized way that directly initializes the HMAC
context without a separate key preparation step.
Reimplement the one-shot raw key functions hmac_sha*_usingrawkey() on
top of the new functions, which makes them a bit more efficient.
Reviewed-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250711215844.41715-1-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Since HMAC support is commonly needed and is fairly simple, include it
as a first-class citizen of the SHA-256 library.
The API supports both incremental and one-shot computation, and either
preparing the key ahead of time or just using a raw key. The
implementation is much more streamlined than crypto/hmac.c.
I've kept it consistent with the HMAC-SHA384 and HMAC-SHA512 code as
much as possible.
Testing of these functions will be via sha224_kunit and sha256_kunit,
added by a later commit.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-9-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Currently the SHA-224 and SHA-256 library functions can be mixed
arbitrarily, even in ways that are incorrect, for example using
sha224_init() and sha256_final(). This is because they operate on the
same structure, sha256_state.
Introduce stronger typing, as I did for SHA-384 and SHA-512.
Also as I did for SHA-384 and SHA-512, use the names *_ctx instead of
*_state. The *_ctx names have the following small benefits:
- They're shorter.
- They avoid an ambiguity with the compression function state.
- They're consistent with the well-known OpenSSL API.
- Users usually name the variable 'sctx' anyway, which suggests that
*_ctx would be the more natural name for the actual struct.
Therefore: update the SHA-224 and SHA-256 APIs, implementation, and
calling code accordingly.
In the new structs, also strongly-type the compression function state.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-7-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add a one-shot SHA-224 computation function sha224(), for consistency
with sha256(), sha384(), and sha512() which all already exist.
Similarly, add sha224_update(). While for now it's identical to
sha256_update(), omitting it makes the API harder to use since users
have to "know" which functions are the same between SHA-224 and SHA-256.
Also, this is a prerequisite for using different context types for each.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-6-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
First, move the declarations of sha224_init/update/final to be just
above the corresponding SHA-256 code, matching the order that I used for
SHA-384 and SHA-512. In sha2.h, the end result is that SHA-224,
SHA-256, SHA-384, and SHA-512 are all in the logical order.
Second, move sha224_block_init() and sha256_block_init() to be just
below crypto_sha256_state. In later changes, these functions as well as
struct crypto_sha256_state will no longer be used by the library
functions. They'll remain just for some legacy offload drivers. This
gets them into a logical place in the file for that.
No code changes other than reordering.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160645.3198-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Since HMAC support is commonly needed and is fairly simple, include it
as a first-class citizen of the SHA-512 library.
The API supports both incremental and one-shot computation, and either
preparing the key ahead of time or just using a raw key. The
implementation is much more streamlined than crypto/hmac.c.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160320.2888-4-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Add basic support for SHA-384 and SHA-512 to lib/crypto/.
Various in-kernel users will be able to use this instead of the
old-school crypto API, which is harder to use and has more overhead.
The basic support added by this commit consists of the API and its
documentation, backed by a C implementation of the algorithms.
sha512_block_generic() is derived from crypto/sha512_generic.c.
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Link: https://lore.kernel.org/r/20250630160320.2888-3-ebiggers@kernel.org
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
The shash interface already handles partial blocks, use it for
sha224-generic and sha256-generic instead of going through the
lib/sha256 interface.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Follow best practices by changing the length parameters to size_t and
explicitly specifying the length of the output digest arrays.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
As has been done for various other algorithms, rework the design of the
SHA-256 library to support arch-optimized implementations, and make
crypto/sha256.c expose both generic and arch-optimized shash algorithms
that wrap the library functions.
This allows users of the SHA-256 library functions to take advantage of
the arch-optimized code, and this makes it much simpler to integrate
SHA-256 for each architecture.
Note that sha256_base.h is not used in the new design. It will be
removed once all the architecture-specific code has been updated.
Move the generic block function into its own module to avoid a circular
dependency from libsha256.ko => sha256-$ARCH.ko => libsha256.ko.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Add export and import functions to maintain existing export format.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Extract the common partial block handling into a helper macro
that can be reused by other library code.
Also delete the unused sha256_base_do_finalize function.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
The function sha224_update is exactly the same as sha256_update.
Moreover it's not even used in the kernel so it can be removed.
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Currently <crypto/sha.h> contains declarations for both SHA-1 and SHA-2,
and <crypto/sha3.h> contains declarations for SHA-3.
This organization is inconsistent, but more importantly SHA-1 is no
longer considered to be cryptographically secure. So to the extent
possible, SHA-1 shouldn't be grouped together with any of the other SHA
versions, and usage of it should be phased out.
Therefore, split <crypto/sha.h> into two headers <crypto/sha1.h> and
<crypto/sha2.h>, and make everyone explicitly specify whether they want
the declarations for SHA-1, SHA-2, or both.
This avoids making the SHA-1 declarations visible to files that don't
want anything to do with SHA-1. It also prepares for potentially moving
sha1.h into a new insecure/ or dangerous/ directory.
Signed-off-by: Eric Biggers <ebiggers@google.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>
Acked-by: Jason A. Donenfeld <Jason@zx2c4.com>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
