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Introduce hash context to support pluggable SHA256 compression

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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.
This commit is contained in:
furszy
2025-12-17 11:15:33 -05:00
parent 95e6815843
commit fdb6a91a5e
21 changed files with 313 additions and 238 deletions
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12
src/modules/ecdh/main_impl.h
View File

@@ -10,20 +10,24 @@
#include "../../../include/secp256k1_ecdh.h"
#include "../../ecmult_const_impl.h"
static int ecdh_hash_function_sha256(unsigned char *output, const unsigned char *x32, const unsigned char *y32, void *data) {
static int ecdh_hash_function_sha256_impl(const secp256k1_hash_ctx *hash_ctx, unsigned char *output, const unsigned char *x32, const unsigned char *y32, void *data) {
unsigned char version = (y32[31] & 0x01) | 0x02;
secp256k1_sha256 sha;
(void)data;
secp256k1_sha256_initialize(&sha);
secp256k1_sha256_write(&sha, &version, 1);
secp256k1_sha256_write(&sha, x32, 32);
secp256k1_sha256_finalize(&sha, output);
secp256k1_sha256_write(hash_ctx, &sha, &version, 1);
secp256k1_sha256_write(hash_ctx, &sha, x32, 32);
secp256k1_sha256_finalize(hash_ctx, &sha, output);
secp256k1_sha256_clear(&sha);
return 1;
}
static int ecdh_hash_function_sha256(unsigned char *output, const unsigned char *x32, const unsigned char *y32, void *data) {
return ecdh_hash_function_sha256_impl(secp256k1_get_hash_context(secp256k1_context_static), output, x32, y32, data);
}
const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_sha256 = ecdh_hash_function_sha256;
const secp256k1_ecdh_hash_function secp256k1_ecdh_hash_function_default = ecdh_hash_function_sha256;

4
src/modules/ecdh/tests_impl.h
View File

@@ -83,8 +83,8 @@ static void test_ecdh_generator_basepoint(void) {
/* compute "explicitly" */
CHECK(secp256k1_ec_pubkey_serialize(CTX, point_ser, &point_ser_len, &point[1], SECP256K1_EC_COMPRESSED) == 1);
secp256k1_sha256_initialize(&sha);
secp256k1_sha256_write(&sha, point_ser, point_ser_len);
secp256k1_sha256_finalize(&sha, output_ser);
secp256k1_sha256_write(secp256k1_get_hash_context(CTX), &sha, point_ser, point_ser_len);
secp256k1_sha256_finalize(secp256k1_get_hash_context(CTX), &sha, output_ser);
/* compare */
CHECK(secp256k1_memcmp_var(output_ecdh, output_ser, 32) == 0);
}