[Pkg-bitcoin-commits] [libsecp256k1] 17/27: exhaustive tests: add recovery module
Jonas Smedegaard
dr at jones.dk
Tue Jan 10 21:47:17 UTC 2017
This is an automated email from the git hooks/post-receive script.
js pushed a commit to branch master
in repository libsecp256k1.
commit 2cee5fd4c9213848cb1bf6f50f4d09a0bd609ea0
Author: Andrew Poelstra <apoelstra at wpsoftware.net>
Date: Mon Nov 28 22:43:04 2016 +0000
exhaustive tests: add recovery module
---
src/tests_exhaustive.c | 135 +++++++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 135 insertions(+)
diff --git a/src/tests_exhaustive.c b/src/tests_exhaustive.c
index 69d91c9..b040bb0 100644
--- a/src/tests_exhaustive.c
+++ b/src/tests_exhaustive.c
@@ -26,6 +26,11 @@
#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);
@@ -282,6 +287,130 @@ void test_exhaustive_sign(const secp256k1_context *ctx, const secp256k1_ge *grou
*/
}
+#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];
@@ -330,6 +459,12 @@ int main(void) {
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;
}
--
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