diff --git a/src/secp256k1/src/tests.c b/src/secp256k1/src/tests.c --- a/src/secp256k1/src/tests.c +++ b/src/secp256k1/src/tests.c @@ -2633,6 +2633,87 @@ ge_equals_ge(&res3, &secp256k1_ge_const_g); } +/* These scalars reach large (in absolute value) outputs when fed to secp256k1_scalar_split_lambda. + * + * They are computed as: + * - For a in [-2, -1, 0, 1, 2]: + * - For b in [-3, -1, 1, 3]: + * - Output (a*LAMBDA + (ORDER+b)/2) % ORDER + */ +static const secp256k1_scalar scalars_near_split_bounds[20] = { + SECP256K1_SCALAR_CONST(0xd938a566, 0x7f479e3e, 0xb5b3c7fa, 0xefdb3749, 0x3aa0585c, 0xc5ea2367, 0xe1b660db, 0x0209e6fc), + SECP256K1_SCALAR_CONST(0xd938a566, 0x7f479e3e, 0xb5b3c7fa, 0xefdb3749, 0x3aa0585c, 0xc5ea2367, 0xe1b660db, 0x0209e6fd), + SECP256K1_SCALAR_CONST(0xd938a566, 0x7f479e3e, 0xb5b3c7fa, 0xefdb3749, 0x3aa0585c, 0xc5ea2367, 0xe1b660db, 0x0209e6fe), + SECP256K1_SCALAR_CONST(0xd938a566, 0x7f479e3e, 0xb5b3c7fa, 0xefdb3749, 0x3aa0585c, 0xc5ea2367, 0xe1b660db, 0x0209e6ff), + SECP256K1_SCALAR_CONST(0x2c9c52b3, 0x3fa3cf1f, 0x5ad9e3fd, 0x77ed9ba5, 0xb294b893, 0x3722e9a5, 0x00e698ca, 0x4cf7632d), + SECP256K1_SCALAR_CONST(0x2c9c52b3, 0x3fa3cf1f, 0x5ad9e3fd, 0x77ed9ba5, 0xb294b893, 0x3722e9a5, 0x00e698ca, 0x4cf7632e), + SECP256K1_SCALAR_CONST(0x2c9c52b3, 0x3fa3cf1f, 0x5ad9e3fd, 0x77ed9ba5, 0xb294b893, 0x3722e9a5, 0x00e698ca, 0x4cf7632f), + SECP256K1_SCALAR_CONST(0x2c9c52b3, 0x3fa3cf1f, 0x5ad9e3fd, 0x77ed9ba5, 0xb294b893, 0x3722e9a5, 0x00e698ca, 0x4cf76330), + SECP256K1_SCALAR_CONST(0x7fffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xd576e735, 0x57a4501d, 0xdfe92f46, 0x681b209f), + SECP256K1_SCALAR_CONST(0x7fffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xd576e735, 0x57a4501d, 0xdfe92f46, 0x681b20a0), + SECP256K1_SCALAR_CONST(0x7fffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xd576e735, 0x57a4501d, 0xdfe92f46, 0x681b20a1), + SECP256K1_SCALAR_CONST(0x7fffffff, 0xffffffff, 0xffffffff, 0xffffffff, 0xd576e735, 0x57a4501d, 0xdfe92f46, 0x681b20a2), + SECP256K1_SCALAR_CONST(0xd363ad4c, 0xc05c30e0, 0xa5261c02, 0x88126459, 0xf85915d7, 0x7825b696, 0xbeebc5c2, 0x833ede11), + SECP256K1_SCALAR_CONST(0xd363ad4c, 0xc05c30e0, 0xa5261c02, 0x88126459, 0xf85915d7, 0x7825b696, 0xbeebc5c2, 0x833ede12), + SECP256K1_SCALAR_CONST(0xd363ad4c, 0xc05c30e0, 0xa5261c02, 0x88126459, 0xf85915d7, 0x7825b696, 0xbeebc5c2, 0x833ede13), + SECP256K1_SCALAR_CONST(0xd363ad4c, 0xc05c30e0, 0xa5261c02, 0x88126459, 0xf85915d7, 0x7825b696, 0xbeebc5c2, 0x833ede14), + SECP256K1_SCALAR_CONST(0x26c75a99, 0x80b861c1, 0x4a4c3805, 0x1024c8b4, 0x704d760e, 0xe95e7cd3, 0xde1bfdb1, 0xce2c5a42), + SECP256K1_SCALAR_CONST(0x26c75a99, 0x80b861c1, 0x4a4c3805, 0x1024c8b4, 0x704d760e, 0xe95e7cd3, 0xde1bfdb1, 0xce2c5a43), + SECP256K1_SCALAR_CONST(0x26c75a99, 0x80b861c1, 0x4a4c3805, 0x1024c8b4, 0x704d760e, 0xe95e7cd3, 0xde1bfdb1, 0xce2c5a44), + SECP256K1_SCALAR_CONST(0x26c75a99, 0x80b861c1, 0x4a4c3805, 0x1024c8b4, 0x704d760e, 0xe95e7cd3, 0xde1bfdb1, 0xce2c5a45) +}; + +void test_ecmult_target(const secp256k1_scalar* target, int mode) { + /* Mode: 0=ecmult_gen, 1=ecmult, 2=ecmult_const */ + secp256k1_scalar n1, n2; + secp256k1_ge p; + secp256k1_gej pj, p1j, p2j, ptj; + static const secp256k1_scalar zero = SECP256K1_SCALAR_CONST(0, 0, 0, 0, 0, 0, 0, 0); + + /* Generate random n1,n2 such that n1+n2 = -target. */ + random_scalar_order_test(&n1); + secp256k1_scalar_add(&n2, &n1, target); + secp256k1_scalar_negate(&n2, &n2); + + /* Generate a random input point. */ + if (mode != 0) { + random_group_element_test(&p); + secp256k1_gej_set_ge(&pj, &p); + } + + /* EC multiplications */ + if (mode == 0) { + secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &p1j, &n1); + secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &p2j, &n2); + secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &ptj, target); + } else if (mode == 1) { + secp256k1_ecmult(&ctx->ecmult_ctx, &p1j, &pj, &n1, &zero); + secp256k1_ecmult(&ctx->ecmult_ctx, &p2j, &pj, &n2, &zero); + secp256k1_ecmult(&ctx->ecmult_ctx, &ptj, &pj, target, &zero); + } else { + secp256k1_ecmult_const(&p1j, &p, &n1, 256); + secp256k1_ecmult_const(&p2j, &p, &n2, 256); + secp256k1_ecmult_const(&ptj, &p, target, 256); + } + + /* Add them all up: n1*P + n2*P + target*P = (n1+n2+target)*P = (n1+n1-n1-n2)*P = 0. */ + secp256k1_gej_add_var(&ptj, &ptj, &p1j, NULL); + secp256k1_gej_add_var(&ptj, &ptj, &p2j, NULL); + CHECK(secp256k1_gej_is_infinity(&ptj)); +} + +void run_ecmult_near_split_bound(void) { + int i; + unsigned j; + for (i = 0; i < 4*count; ++i) { + for (j = 0; j < sizeof(scalars_near_split_bounds) / sizeof(scalars_near_split_bounds[0]); ++j) { + test_ecmult_target(&scalars_near_split_bounds[j], 0); + test_ecmult_target(&scalars_near_split_bounds[j], 1); + test_ecmult_target(&scalars_near_split_bounds[j], 2); + } + } +} + void run_point_times_order(void) { int i; secp256k1_fe x = SECP256K1_FE_CONST(0, 0, 0, 0, 0, 0, 0, 2); @@ -3552,14 +3633,12 @@ #ifdef USE_ENDOMORPHISM /***** ENDOMORPHISH TESTS *****/ -void test_scalar_split(void) { - secp256k1_scalar full; +void test_scalar_split(const secp256k1_scalar* full) { secp256k1_scalar s1, slam; const unsigned char zero[32] = {0}; unsigned char tmp[32]; - random_scalar_order_test(&full); - secp256k1_scalar_split_lambda(&s1, &slam, &full); + secp256k1_scalar_split_lambda(&s1, &slam, full); /* check that both are <= 128 bits in size */ if (secp256k1_scalar_is_high(&s1)) { @@ -3575,8 +3654,17 @@ CHECK(secp256k1_memcmp_var(zero, tmp, 16) == 0); } + void run_endomorphism_tests(void) { - test_scalar_split(); + unsigned i; + for (i = 0; i < 100U * count; ++i) { + secp256k1_scalar full; + random_scalar_order_test(&full); + test_scalar_split(&full); + } + for (i = 0; i < sizeof(scalars_near_split_bounds) / sizeof(scalars_near_split_bounds[0]); ++i) { + test_scalar_split(&scalars_near_split_bounds[i]); + } } #endif @@ -5596,6 +5684,7 @@ /* ecmult tests */ run_wnaf(); run_point_times_order(); + run_ecmult_near_split_bound(); run_ecmult_chain(); run_ecmult_constants(); run_ecmult_gen_blind();