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Add two ECDSA edge case tests #126

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Merged
sipa merged 2 commits into from
Dec 1, 2014
Merged

Add two ECDSA edge case tests #126

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32600e5
Add a test for r >= order signature handling
sipa Dec 1, 2014
24b3c65
Add a test case for ECDSA recomputing infinity
sipa Dec 1, 2014
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31 changes: 31 additions & 0 deletions src/tests.c
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Original file line number Diff line number Diff line change
Expand Up @@ -998,13 +998,44 @@ void test_ecdsa_edge_cases(void) {
unsigned char pubkeyb[33];
int pubkeyblen = 33;
for (int recid = 0; recid < 4; recid++) {
// (4,4) encoded in DER.
unsigned char sigbder[8] = {0x30, 0x06, 0x02, 0x01, 0x04, 0x02, 0x01, 0x04};
// (order + r,4) encoded in DER.
unsigned char sigbderlong[40] = {
0x30, 0x26, 0x02, 0x21, 0x00, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF,
0xFF, 0xFF, 0xFF, 0xFF, 0xFE, 0xBA, 0xAE, 0xDC,
0xE6, 0xAF, 0x48, 0xA0, 0x3B, 0xBF, 0xD2, 0x5E,
0x8C, 0xD0, 0x36, 0x41, 0x45, 0x02, 0x01, 0x04
};
CHECK(secp256k1_ecdsa_recover_compact(msg32, 32, sigb64, pubkeyb, &pubkeyblen, 1, recid));
CHECK(secp256k1_ecdsa_verify(msg32, 32, sigbder, sizeof(sigbder), pubkeyb, pubkeyblen) == 1);
for (int recid2 = 0; recid2 < 4; recid2++) {
unsigned char pubkey2b[33];
int pubkey2blen = 33;
CHECK(secp256k1_ecdsa_recover_compact(msg32, 32, sigb64, pubkey2b, &pubkey2blen, 1, recid2));
// Verifying with (order + r,4) should always fail.
CHECK(secp256k1_ecdsa_verify(msg32, 32, sigbderlong, sizeof(sigbderlong), pubkey2b, pubkey2blen) != 1);
}
/* Damage signature. */
sigbder[7]++;
CHECK(secp256k1_ecdsa_verify(msg32, 32, sigbder, sizeof(sigbder), pubkeyb, pubkeyblen) == 0);
}

/* Test the case where ECDSA recomputes a point that is infinity. */
{
secp256k1_ecdsa_sig_t sig;
secp256k1_scalar_set_int(&sig.s, 1);
secp256k1_scalar_negate(&sig.s, &sig.s);
secp256k1_scalar_inverse(&sig.s, &sig.s);
secp256k1_scalar_set_int(&sig.r, 1);
secp256k1_gej_t keyj;
secp256k1_ecmult_gen(&keyj, &sig.r);
secp256k1_ge_t key;
secp256k1_ge_set_gej(&key, &keyj);
secp256k1_scalar_t msg = sig.s;
CHECK(secp256k1_ecdsa_sig_verify(&sig, &key, &msg) == 0);
}
}

void run_ecdsa_edge_cases(void) {
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