Browse Source

tests: Add failing unit test for #257 (bad addition formula)

master
Andrew Poelstra 7 years ago
parent
commit
8c5d5f7b5b
No known key found for this signature in database
GPG Key ID: C588D63CE41B97C1
  1. 68
      src/tests.c

68
src/tests.c

@ -1146,11 +1146,79 @@ void test_ge(void) { @@ -1146,11 +1146,79 @@ void test_ge(void) {
free(zinv);
}
void test_add_neg_y_diff_x(void) {
/* The point of this test is to check that we can add two points
* whose y-coordinates are negatives of each other but whose x
* coordinates differ. If the x-coordinates were the same, these
* points would be negatives of each other and their sum is
* infinity. This is cool because it "covers up" any degeneracy
* in the addition algorithm that would cause the xy coordinates
* of the sum to be wrong (since infinity has no xy coordinates).
* HOWEVER, if the x-coordinates are different, infinity is the
* wrong answer, and such degeneracies are exposed. This is the
* root of https://github.com/bitcoin/secp256k1/issues/257 which
* this test is a regression test for.
*
* These points were generated in sage as
* # secp256k1 params
* F = FiniteField (0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFEFFFFFC2F)
* C = EllipticCurve ([F (0), F (7)])
* G = C.lift_x(0x79BE667EF9DCBBAC55A06295CE870B07029BFCDB2DCE28D959F2815B16F81798)
* N = FiniteField(G.order())
*
* # endomorphism values (lambda is 1^{1/3} in N, beta is 1^{1/3} in F)
* x = polygen(N)
* lam = (1 - x^3).roots()[1][0]
*
* # random "bad pair"
* P = C.random_element()
* Q = -int(lam) * P
* print " P: %x %x" % P.xy()
* print " Q: %x %x" % Q.xy()
* print "P + Q: %x %x" % (P + Q).xy()
*/
secp256k1_gej_t aj = SECP256K1_GEJ_CONST(
0x8d24cd95, 0x0a355af1, 0x3c543505, 0x44238d30,
0x0643d79f, 0x05a59614, 0x2f8ec030, 0xd58977cb,
0x001e337a, 0x38093dcd, 0x6c0f386d, 0x0b1293a8,
0x4d72c879, 0xd7681924, 0x44e6d2f3, 0x9190117d
);
secp256k1_gej_t bj = SECP256K1_GEJ_CONST(
0xc7b74206, 0x1f788cd9, 0xabd0937d, 0x164a0d86,
0x95f6ff75, 0xf19a4ce9, 0xd013bd7b, 0xbf92d2a7,
0xffe1cc85, 0xc7f6c232, 0x93f0c792, 0xf4ed6c57,
0xb28d3786, 0x2897e6db, 0xbb192d0b, 0x6e6feab2
);
secp256k1_gej_t sumj = SECP256K1_GEJ_CONST(
0x671a63c0, 0x3efdad4c, 0x389a7798, 0x24356027,
0xb3d69010, 0x278625c3, 0x5c86d390, 0x184a8f7a,
0x5f6409c2, 0x2ce01f2b, 0x511fd375, 0x25071d08,
0xda651801, 0x70e95caf, 0x8f0d893c, 0xbed8fbbe
);
secp256k1_ge_t b;
secp256k1_gej_t resj;
secp256k1_ge_t res;
secp256k1_ge_set_gej(&b, &bj);
secp256k1_gej_add_var(&resj, &aj, &bj, NULL);
secp256k1_ge_set_gej(&res, &resj);
ge_equals_gej(&res, &sumj);
secp256k1_gej_add_ge(&resj, &aj, &b);
secp256k1_ge_set_gej(&res, &resj);
ge_equals_gej(&res, &sumj);
secp256k1_gej_add_ge_var(&resj, &aj, &b, NULL);
secp256k1_ge_set_gej(&res, &resj);
ge_equals_gej(&res, &sumj);
}
void run_ge(void) {
int i;
for (i = 0; i < count * 32; i++) {
test_ge();
}
test_add_neg_y_diff_x();
}
/***** ECMULT TESTS *****/

Loading…
Cancel
Save