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Diffstat (limited to 'crypto/secp256k1/libsecp256k1/src/tests_exhaustive.c')
| -rw-r--r-- | crypto/secp256k1/libsecp256k1/src/tests_exhaustive.c | 470 |
1 files changed, 470 insertions, 0 deletions
diff --git a/crypto/secp256k1/libsecp256k1/src/tests_exhaustive.c b/crypto/secp256k1/libsecp256k1/src/tests_exhaustive.c new file mode 100644 index 000000000..b040bb073 --- /dev/null +++ b/crypto/secp256k1/libsecp256k1/src/tests_exhaustive.c @@ -0,0 +1,470 @@ +/*********************************************************************** + * Copyright (c) 2016 Andrew Poelstra * + * Distributed under the MIT software license, see the accompanying * + * file COPYING or http://www.opensource.org/licenses/mit-license.php.* + **********************************************************************/ + +#if defined HAVE_CONFIG_H +#include "libsecp256k1-config.h" +#endif + +#include <stdio.h> +#include <stdlib.h> + +#include <time.h> + +#undef USE_ECMULT_STATIC_PRECOMPUTATION + +#ifndef EXHAUSTIVE_TEST_ORDER +/* see group_impl.h for allowable values */ +#define EXHAUSTIVE_TEST_ORDER 13 +#define EXHAUSTIVE_TEST_LAMBDA 9 /* cube root of 1 mod 13 */ +#endif + +#include "include/secp256k1.h" +#include "group.h" +#include "secp256k1.c" +#include "testrand_impl.h" + +#ifdef ENABLE_MODULE_RECOVERY +#include "src/modules/recovery/main_impl.h" +#include "include/secp256k1_recovery.h" +#endif + +/** stolen from tests.c */ +void ge_equals_ge(const secp256k1_ge *a, const secp256k1_ge *b) { + CHECK(a->infinity == b->infinity); + if (a->infinity) { + return; + } + CHECK(secp256k1_fe_equal_var(&a->x, &b->x)); + CHECK(secp256k1_fe_equal_var(&a->y, &b->y)); +} + +void ge_equals_gej(const secp256k1_ge *a, const secp256k1_gej *b) { + secp256k1_fe z2s; + secp256k1_fe u1, u2, s1, s2; + CHECK(a->infinity == b->infinity); + if (a->infinity) { + return; + } + /* Check a.x * b.z^2 == b.x && a.y * b.z^3 == b.y, to avoid inverses. */ + secp256k1_fe_sqr(&z2s, &b->z); + secp256k1_fe_mul(&u1, &a->x, &z2s); + u2 = b->x; secp256k1_fe_normalize_weak(&u2); + secp256k1_fe_mul(&s1, &a->y, &z2s); secp256k1_fe_mul(&s1, &s1, &b->z); + s2 = b->y; secp256k1_fe_normalize_weak(&s2); + CHECK(secp256k1_fe_equal_var(&u1, &u2)); + CHECK(secp256k1_fe_equal_var(&s1, &s2)); +} + +void random_fe(secp256k1_fe *x) { + unsigned char bin[32]; + do { + secp256k1_rand256(bin); + if (secp256k1_fe_set_b32(x, bin)) { + return; + } + } while(1); +} +/** END stolen from tests.c */ + +int secp256k1_nonce_function_smallint(unsigned char *nonce32, const unsigned char *msg32, + const unsigned char *key32, const unsigned char *algo16, + void *data, unsigned int attempt) { + secp256k1_scalar s; + int *idata = data; + (void)msg32; + (void)key32; + (void)algo16; + /* Some nonces cannot be used because they'd cause s and/or r to be zero. + * The signing function has retry logic here that just re-calls the nonce + * function with an increased `attempt`. So if attempt > 0 this means we + * need to change the nonce to avoid an infinite loop. */ + if (attempt > 0) { + *idata = (*idata + 1) % EXHAUSTIVE_TEST_ORDER; + } + secp256k1_scalar_set_int(&s, *idata); + secp256k1_scalar_get_b32(nonce32, &s); + return 1; +} + +#ifdef USE_ENDOMORPHISM +void test_exhaustive_endomorphism(const secp256k1_ge *group, int order) { + int i; + for (i = 0; i < order; i++) { + secp256k1_ge res; + secp256k1_ge_mul_lambda(&res, &group[i]); + ge_equals_ge(&group[i * EXHAUSTIVE_TEST_LAMBDA % EXHAUSTIVE_TEST_ORDER], &res); + } +} +#endif + +void test_exhaustive_addition(const secp256k1_ge *group, const secp256k1_gej *groupj, int order) { + int i, j; + + /* Sanity-check (and check infinity functions) */ + CHECK(secp256k1_ge_is_infinity(&group[0])); + CHECK(secp256k1_gej_is_infinity(&groupj[0])); + for (i = 1; i < order; i++) { + CHECK(!secp256k1_ge_is_infinity(&group[i])); + CHECK(!secp256k1_gej_is_infinity(&groupj[i])); + } + + /* Check all addition formulae */ + for (j = 0; j < order; j++) { + secp256k1_fe fe_inv; + secp256k1_fe_inv(&fe_inv, &groupj[j].z); + for (i = 0; i < order; i++) { + secp256k1_ge zless_gej; + secp256k1_gej tmp; + /* add_var */ + secp256k1_gej_add_var(&tmp, &groupj[i], &groupj[j], NULL); + ge_equals_gej(&group[(i + j) % order], &tmp); + /* add_ge */ + if (j > 0) { + secp256k1_gej_add_ge(&tmp, &groupj[i], &group[j]); + ge_equals_gej(&group[(i + j) % order], &tmp); + } + /* add_ge_var */ + secp256k1_gej_add_ge_var(&tmp, &groupj[i], &group[j], NULL); + ge_equals_gej(&group[(i + j) % order], &tmp); + /* add_zinv_var */ + zless_gej.infinity = groupj[j].infinity; + zless_gej.x = groupj[j].x; + zless_gej.y = groupj[j].y; + secp256k1_gej_add_zinv_var(&tmp, &groupj[i], &zless_gej, &fe_inv); + ge_equals_gej(&group[(i + j) % order], &tmp); + } + } + + /* Check doubling */ + for (i = 0; i < order; i++) { + secp256k1_gej tmp; + if (i > 0) { + secp256k1_gej_double_nonzero(&tmp, &groupj[i], NULL); + ge_equals_gej(&group[(2 * i) % order], &tmp); + } + secp256k1_gej_double_var(&tmp, &groupj[i], NULL); + ge_equals_gej(&group[(2 * i) % order], &tmp); + } + + /* Check negation */ + for (i = 1; i < order; i++) { + secp256k1_ge tmp; + secp256k1_gej tmpj; + secp256k1_ge_neg(&tmp, &group[i]); + ge_equals_ge(&group[order - i], &tmp); + secp256k1_gej_neg(&tmpj, &groupj[i]); + ge_equals_gej(&group[order - i], &tmpj); + } +} + +void test_exhaustive_ecmult(const secp256k1_context *ctx, const secp256k1_ge *group, const secp256k1_gej *groupj, int order) { + int i, j, r_log; + for (r_log = 1; r_log < order; r_log++) { + for (j = 0; j < order; j++) { + for (i = 0; i < order; i++) { + secp256k1_gej tmp; + secp256k1_scalar na, ng; + secp256k1_scalar_set_int(&na, i); + secp256k1_scalar_set_int(&ng, j); + + secp256k1_ecmult(&ctx->ecmult_ctx, &tmp, &groupj[r_log], &na, &ng); + ge_equals_gej(&group[(i * r_log + j) % order], &tmp); + + if (i > 0) { + secp256k1_ecmult_const(&tmp, &group[i], &ng); + ge_equals_gej(&group[(i * j) % order], &tmp); + } + } + } + } +} + +void r_from_k(secp256k1_scalar *r, const secp256k1_ge *group, int k) { + secp256k1_fe x; + unsigned char x_bin[32]; + k %= EXHAUSTIVE_TEST_ORDER; + x = group[k].x; + secp256k1_fe_normalize(&x); + secp256k1_fe_get_b32(x_bin, &x); + secp256k1_scalar_set_b32(r, x_bin, NULL); +} + +void test_exhaustive_verify(const secp256k1_context *ctx, const secp256k1_ge *group, int order) { + int s, r, msg, key; + for (s = 1; s < order; s++) { + for (r = 1; r < order; r++) { + for (msg = 1; msg < order; msg++) { + for (key = 1; key < order; key++) { + secp256k1_ge nonconst_ge; + secp256k1_ecdsa_signature sig; + secp256k1_pubkey pk; + secp256k1_scalar sk_s, msg_s, r_s, s_s; + secp256k1_scalar s_times_k_s, msg_plus_r_times_sk_s; + int k, should_verify; + unsigned char msg32[32]; + + secp256k1_scalar_set_int(&s_s, s); + secp256k1_scalar_set_int(&r_s, r); + secp256k1_scalar_set_int(&msg_s, msg); + secp256k1_scalar_set_int(&sk_s, key); + + /* Verify by hand */ + /* Run through every k value that gives us this r and check that *one* works. + * Note there could be none, there could be multiple, ECDSA is weird. */ + should_verify = 0; + for (k = 0; k < order; k++) { + secp256k1_scalar check_x_s; + r_from_k(&check_x_s, group, k); + if (r_s == check_x_s) { + secp256k1_scalar_set_int(&s_times_k_s, k); + secp256k1_scalar_mul(&s_times_k_s, &s_times_k_s, &s_s); + secp256k1_scalar_mul(&msg_plus_r_times_sk_s, &r_s, &sk_s); + secp256k1_scalar_add(&msg_plus_r_times_sk_s, &msg_plus_r_times_sk_s, &msg_s); + should_verify |= secp256k1_scalar_eq(&s_times_k_s, &msg_plus_r_times_sk_s); + } + } + /* nb we have a "high s" rule */ + should_verify &= !secp256k1_scalar_is_high(&s_s); + + /* Verify by calling verify */ + secp256k1_ecdsa_signature_save(&sig, &r_s, &s_s); + memcpy(&nonconst_ge, &group[sk_s], sizeof(nonconst_ge)); + secp256k1_pubkey_save(&pk, &nonconst_ge); + secp256k1_scalar_get_b32(msg32, &msg_s); + CHECK(should_verify == + secp256k1_ecdsa_verify(ctx, &sig, msg32, &pk)); + } + } + } + } +} + +void test_exhaustive_sign(const secp256k1_context *ctx, const secp256k1_ge *group, int order) { + int i, j, k; + + /* Loop */ + for (i = 1; i < order; i++) { /* message */ + for (j = 1; j < order; j++) { /* key */ + for (k = 1; k < order; k++) { /* nonce */ + const int starting_k = k; + secp256k1_ecdsa_signature sig; + secp256k1_scalar sk, msg, r, s, expected_r; + unsigned char sk32[32], msg32[32]; + secp256k1_scalar_set_int(&msg, i); + secp256k1_scalar_set_int(&sk, j); + secp256k1_scalar_get_b32(sk32, &sk); + secp256k1_scalar_get_b32(msg32, &msg); + + secp256k1_ecdsa_sign(ctx, &sig, msg32, sk32, secp256k1_nonce_function_smallint, &k); + + secp256k1_ecdsa_signature_load(ctx, &r, &s, &sig); + /* Note that we compute expected_r *after* signing -- this is important + * because our nonce-computing function function might change k during + * signing. */ + r_from_k(&expected_r, group, k); + CHECK(r == expected_r); + CHECK((k * s) % order == (i + r * j) % order || + (k * (EXHAUSTIVE_TEST_ORDER - s)) % order == (i + r * j) % order); + + /* Overflow means we've tried every possible nonce */ + if (k < starting_k) { + break; + } + } + } + } + + /* We would like to verify zero-knowledge here by counting how often every + * possible (s, r) tuple appears, but because the group order is larger + * than the field order, when coercing the x-values to scalar values, some + * appear more often than others, so we are actually not zero-knowledge. + * (This effect also appears in the real code, but the difference is on the + * order of 1/2^128th the field order, so the deviation is not useful to a + * computationally bounded attacker.) + */ +} + +#ifdef ENABLE_MODULE_RECOVERY +void test_exhaustive_recovery_sign(const secp256k1_context *ctx, const secp256k1_ge *group, int order) { + int i, j, k; + + /* Loop */ + for (i = 1; i < order; i++) { /* message */ + for (j = 1; j < order; j++) { /* key */ + for (k = 1; k < order; k++) { /* nonce */ + const int starting_k = k; + secp256k1_fe r_dot_y_normalized; + secp256k1_ecdsa_recoverable_signature rsig; + secp256k1_ecdsa_signature sig; + secp256k1_scalar sk, msg, r, s, expected_r; + unsigned char sk32[32], msg32[32]; + int expected_recid; + int recid; + secp256k1_scalar_set_int(&msg, i); + secp256k1_scalar_set_int(&sk, j); + secp256k1_scalar_get_b32(sk32, &sk); + secp256k1_scalar_get_b32(msg32, &msg); + + secp256k1_ecdsa_sign_recoverable(ctx, &rsig, msg32, sk32, secp256k1_nonce_function_smallint, &k); + + /* Check directly */ + secp256k1_ecdsa_recoverable_signature_load(ctx, &r, &s, &recid, &rsig); + r_from_k(&expected_r, group, k); + CHECK(r == expected_r); + CHECK((k * s) % order == (i + r * j) % order || + (k * (EXHAUSTIVE_TEST_ORDER - s)) % order == (i + r * j) % order); + /* In computing the recid, there is an overflow condition that is disabled in + * scalar_low_impl.h `secp256k1_scalar_set_b32` because almost every r.y value + * will exceed the group order, and our signing code always holds out for r + * values that don't overflow, so with a proper overflow check the tests would + * loop indefinitely. */ + r_dot_y_normalized = group[k].y; + secp256k1_fe_normalize(&r_dot_y_normalized); + /* Also the recovery id is flipped depending if we hit the low-s branch */ + if ((k * s) % order == (i + r * j) % order) { + expected_recid = secp256k1_fe_is_odd(&r_dot_y_normalized) ? 1 : 0; + } else { + expected_recid = secp256k1_fe_is_odd(&r_dot_y_normalized) ? 0 : 1; + } + CHECK(recid == expected_recid); + + /* Convert to a standard sig then check */ + secp256k1_ecdsa_recoverable_signature_convert(ctx, &sig, &rsig); + secp256k1_ecdsa_signature_load(ctx, &r, &s, &sig); + /* Note that we compute expected_r *after* signing -- this is important + * because our nonce-computing function function might change k during + * signing. */ + r_from_k(&expected_r, group, k); + CHECK(r == expected_r); + CHECK((k * s) % order == (i + r * j) % order || + (k * (EXHAUSTIVE_TEST_ORDER - s)) % order == (i + r * j) % order); + + /* Overflow means we've tried every possible nonce */ + if (k < starting_k) { + break; + } + } + } + } +} + +void test_exhaustive_recovery_verify(const secp256k1_context *ctx, const secp256k1_ge *group, int order) { + /* This is essentially a copy of test_exhaustive_verify, with recovery added */ + int s, r, msg, key; + for (s = 1; s < order; s++) { + for (r = 1; r < order; r++) { + for (msg = 1; msg < order; msg++) { + for (key = 1; key < order; key++) { + secp256k1_ge nonconst_ge; + secp256k1_ecdsa_recoverable_signature rsig; + secp256k1_ecdsa_signature sig; + secp256k1_pubkey pk; + secp256k1_scalar sk_s, msg_s, r_s, s_s; + secp256k1_scalar s_times_k_s, msg_plus_r_times_sk_s; + int recid = 0; + int k, should_verify; + unsigned char msg32[32]; + + secp256k1_scalar_set_int(&s_s, s); + secp256k1_scalar_set_int(&r_s, r); + secp256k1_scalar_set_int(&msg_s, msg); + secp256k1_scalar_set_int(&sk_s, key); + secp256k1_scalar_get_b32(msg32, &msg_s); + + /* Verify by hand */ + /* Run through every k value that gives us this r and check that *one* works. + * Note there could be none, there could be multiple, ECDSA is weird. */ + should_verify = 0; + for (k = 0; k < order; k++) { + secp256k1_scalar check_x_s; + r_from_k(&check_x_s, group, k); + if (r_s == check_x_s) { + secp256k1_scalar_set_int(&s_times_k_s, k); + secp256k1_scalar_mul(&s_times_k_s, &s_times_k_s, &s_s); + secp256k1_scalar_mul(&msg_plus_r_times_sk_s, &r_s, &sk_s); + secp256k1_scalar_add(&msg_plus_r_times_sk_s, &msg_plus_r_times_sk_s, &msg_s); + should_verify |= secp256k1_scalar_eq(&s_times_k_s, &msg_plus_r_times_sk_s); + } + } + /* nb we have a "high s" rule */ + should_verify &= !secp256k1_scalar_is_high(&s_s); + + /* We would like to try recovering the pubkey and checking that it matches, + * but pubkey recovery is impossible in the exhaustive tests (the reason + * being that there are 12 nonzero r values, 12 nonzero points, and no + * overlap between the sets, so there are no valid signatures). */ + + /* Verify by converting to a standard signature and calling verify */ + secp256k1_ecdsa_recoverable_signature_save(&rsig, &r_s, &s_s, recid); + secp256k1_ecdsa_recoverable_signature_convert(ctx, &sig, &rsig); + memcpy(&nonconst_ge, &group[sk_s], sizeof(nonconst_ge)); + secp256k1_pubkey_save(&pk, &nonconst_ge); + CHECK(should_verify == + secp256k1_ecdsa_verify(ctx, &sig, msg32, &pk)); + } + } + } + } +} +#endif + +int main(void) { + int i; + secp256k1_gej groupj[EXHAUSTIVE_TEST_ORDER]; + secp256k1_ge group[EXHAUSTIVE_TEST_ORDER]; + + /* Build context */ + secp256k1_context *ctx = secp256k1_context_create(SECP256K1_CONTEXT_SIGN | SECP256K1_CONTEXT_VERIFY); + + /* TODO set z = 1, then do num_tests runs with random z values */ + + /* Generate the entire group */ + secp256k1_gej_set_infinity(&groupj[0]); + secp256k1_ge_set_gej(&group[0], &groupj[0]); + for (i = 1; i < EXHAUSTIVE_TEST_ORDER; i++) { + /* Set a different random z-value for each Jacobian point */ + secp256k1_fe z; + random_fe(&z); + + secp256k1_gej_add_ge(&groupj[i], &groupj[i - 1], &secp256k1_ge_const_g); + secp256k1_ge_set_gej(&group[i], &groupj[i]); + secp256k1_gej_rescale(&groupj[i], &z); + + /* Verify against ecmult_gen */ + { + secp256k1_scalar scalar_i; + secp256k1_gej generatedj; + secp256k1_ge generated; + + secp256k1_scalar_set_int(&scalar_i, i); + secp256k1_ecmult_gen(&ctx->ecmult_gen_ctx, &generatedj, &scalar_i); + secp256k1_ge_set_gej(&generated, &generatedj); + + CHECK(group[i].infinity == 0); + CHECK(generated.infinity == 0); + CHECK(secp256k1_fe_equal_var(&generated.x, &group[i].x)); + CHECK(secp256k1_fe_equal_var(&generated.y, &group[i].y)); + } + } + + /* Run the tests */ +#ifdef USE_ENDOMORPHISM + test_exhaustive_endomorphism(group, EXHAUSTIVE_TEST_ORDER); +#endif + test_exhaustive_addition(group, groupj, EXHAUSTIVE_TEST_ORDER); + test_exhaustive_ecmult(ctx, group, groupj, EXHAUSTIVE_TEST_ORDER); + test_exhaustive_sign(ctx, group, EXHAUSTIVE_TEST_ORDER); + test_exhaustive_verify(ctx, group, EXHAUSTIVE_TEST_ORDER); + +#ifdef ENABLE_MODULE_RECOVERY + test_exhaustive_recovery_sign(ctx, group, EXHAUSTIVE_TEST_ORDER); + test_exhaustive_recovery_verify(ctx, group, EXHAUSTIVE_TEST_ORDER); +#endif + + secp256k1_context_destroy(ctx); + return 0; +} + |