4d92a083bc sha256: speed up writes using multi-block compression (furszy)
0753f8b909 Add API to override SHA256 compression at runtime (furszy)
fdb6a91a5e Introduce hash context to support pluggable SHA256 compression (furszy)
Pull request description:
Tackling the long-standing request #702.
Right now we ship our own SHA256 implementation, a standard baseline version that does not take advantage of any hardware-optimized instruction, and it cannot be accessed by the embedding application - it is for internal usage only.
This means embedding applications often have to implement or include a different version for their use cases, wasting space on constrained environments, and in performance-sensitive setups it forces them to use a slower path than what the platform provides. Many projects already rely on tuned SHA-NI / ARMv8 / or other hardware-optimized code, so always using the baseline implementation we ship within the library is not ideal.
These changes allow users to supply their own SHA256 compression function at runtime, while preserving the existing default behavior for everyone else. This is primarily intended for environments where the available SHA256 implementation is detected dynamically and recompiling the library with a different implementation is not feasible (equivalent build-time functionality will come in a follow-up PR).
It introduces a new API:
```C89
secp256k1_context_set_sha256_transform_callback(ctx, fn_transform)
```
This function installs the optimized SHA256 compression into the `secp256k1_context`, which is then used by all internal computations. Important: The provided function is verified to be output-equivalent to the original one.
As a quick example, using this functionality in Bitcoin-Core will be very straightforward: f68bef06d9
ACKs for top commit:
real-or-random:
ACK 4d92a083bc
w0xlt:
ACK 4d92a083bc
theStack:
ACK 4d92a083bc
Tree-SHA512: 058e2e82071f1ca77254b684458292c621e60d65bbcc5500574429717e7db75bc9f3221129fafd11eb5d33e666a5efec5e9844460d3b194ef3b6b16f2df28fb9
This is purely a mechanical change with no behavior change.
It introduces a secp256k1_hash_ctx struct inside secp256k1_context
and propagates it to all SHA256-related operations.
This sets up the ability to provide a hardware-optimized SHA256
compression function at runtime in a follow-up commit.
In the bench and bench_internal help functions argv was not being
passed, in this change we pass in argv[0] and use it in the help text.
Additionally instead of passing all of argv in bench_ecmult we now
just pass argv[0] and is used as the executable_path variable.
In this change the get_iters function was updated to print an error
message and then return 0. In the functions that use get_iters they
print the help text and then EXIT_FAILURE
The following functions were created:
1. bench.c: help()
- prints the help to the command-line
2. bench.h: have_invalid_args()
- takes a list of arguments that the user is allowed to enter on the command-line
- returns 1 if the user entered an invalid argument
- returns 0 if all the user entered arguments are valid
Previously "ecmult{,_multi} xg" meant multiplication with (x - 1) random points
and base point G. Now
- ecmult_{,multi_}xp means multiplication with x random points and
- ecmult_{,multi_}xp_g means multiplication with x random points and G
1. add `print_output_table_header_row` func to print the table header for benchmark output
2. modify the following benchmarks to include the table header
- bench_ecdh.c
- bench_ecmult.c
- bench_internal.c
- bench_recover.c
- bench_schnorrsig.c
- bench_sign.c
- bench_verify.c
0f05173 Fix algorithm selection in bench_ecmult (Jonas Nick)
Pull request description:
Without this commit using an unknown argument results in a segmentation fault.
Tree-SHA512: 85b8f977e62fa360ff6dc923bd86f08725c30e178d58f43d33cbd8eb69e54fa4ec76e4407624611a80554cf9961689bce6b216da735ac95b256d0d2f60fe3328
