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Add exhaustive test for ellswift (create+decode roundtrip)

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Co-authored-by: Pieter Wuille <pieter@wuille.net>
Co-authored-by: Tim Ruffing <crypto@timruffing.de>
This commit is contained in:
Sebastian Falbesoner 2023-07-04 02:50:05 +02:00
parent 332af315fc
commit 2792119278
3 changed files with 56 additions and 0 deletions
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1
src/modules/ellswift/Makefile.am.include
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@ -2,3 +2,4 @@ include_HEADERS += include/secp256k1_ellswift.h
noinst_HEADERS += src/modules/ellswift/bench_impl.h
noinst_HEADERS += src/modules/ellswift/main_impl.h
noinst_HEADERS += src/modules/ellswift/tests_impl.h
noinst_HEADERS += src/modules/ellswift/tests_exhaustive_impl.h

39
src/modules/ellswift/tests_exhaustive_impl.h Normal file
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@ -0,0 +1,39 @@
/***********************************************************************
* Distributed under the MIT software license, see the accompanying *
* file COPYING or https://www.opensource.org/licenses/mit-license.php.*
***********************************************************************/
#ifndef SECP256K1_MODULE_ELLSWIFT_TESTS_EXHAUSTIVE_H
#define SECP256K1_MODULE_ELLSWIFT_TESTS_EXHAUSTIVE_H
#include "../../../include/secp256k1_ellswift.h"
#include "main_impl.h"
static void test_exhaustive_ellswift(const secp256k1_context *ctx, const secp256k1_ge *group) {
int i;
/* Note that SwiftEC/ElligatorSwift are inherently curve operations, not
* group operations, and this test only checks the curve points which are in
* a tiny subgroup. In that sense it can't be really seen as exhaustive as
* it doesn't (and for computational reasons obviously cannot) test the
* entire domain ellswift operates under. */
for (i = 1; i < EXHAUSTIVE_TEST_ORDER; i++) {
secp256k1_scalar scalar_i;
unsigned char sec32[32];
unsigned char ell64[64];
secp256k1_pubkey pub_decoded;
secp256k1_ge ge_decoded;
/* Construct ellswift pubkey from exhaustive loop scalar i. */
secp256k1_scalar_set_int(&scalar_i, i);
secp256k1_scalar_get_b32(sec32, &scalar_i);
CHECK(secp256k1_ellswift_create(ctx, ell64, sec32, NULL));
/* Decode ellswift pubkey and check that it matches the precomputed group element. */
secp256k1_ellswift_decode(ctx, &pub_decoded, ell64);
secp256k1_pubkey_load(ctx, &ge_decoded, &pub_decoded);
ge_equals_ge(&ge_decoded, &group[i]);
}
}
#endif

16
src/tests_exhaustive.c
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@ -13,6 +13,9 @@
#define EXHAUSTIVE_TEST_ORDER 13
#endif
/* These values of B are all values in [1, 8] that result in a curve with even order. */
#define EXHAUSTIVE_TEST_CURVE_HAS_EVEN_ORDER (SECP256K1_B == 1 || SECP256K1_B == 6 || SECP256K1_B == 8)
#ifdef USE_EXTERNAL_DEFAULT_CALLBACKS
#pragma message("Ignoring USE_EXTERNAL_CALLBACKS in exhaustive_tests.")
#undef USE_EXTERNAL_DEFAULT_CALLBACKS
@ -395,6 +398,10 @@ static void test_exhaustive_sign(const secp256k1_context *ctx, const secp256k1_g
#include "modules/schnorrsig/tests_exhaustive_impl.h"
#endif
#ifdef ENABLE_MODULE_ELLSWIFT
#include "modules/ellswift/tests_exhaustive_impl.h"
#endif
int main(int argc, char** argv) {
int i;
secp256k1_gej groupj[EXHAUSTIVE_TEST_ORDER];
@ -490,6 +497,15 @@ int main(int argc, char** argv) {
#ifdef ENABLE_MODULE_SCHNORRSIG
test_exhaustive_schnorrsig(ctx);
#endif
#ifdef ENABLE_MODULE_ELLSWIFT
/* The ellswift algorithm does have additional edge cases when operating on
* curves of even order, which are not included in the code as secp256k1 is
* of odd order. Skip the ellswift tests if the used exhaustive tests curve
* is even-ordered accordingly. */
#if !EXHAUSTIVE_TEST_CURVE_HAS_EVEN_ORDER
test_exhaustive_ellswift(ctx, group);
#endif
#endif
secp256k1_context_destroy(ctx);
}