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fix(crypto): Treat point at infinity as an invalid public key in ecdsa_recover_pub_from_sig().

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This commit is contained in:
Andrew Kozlik 2022-01-05 17:01:35 +01:00 committed by Andrew Kozlik
parent 33c243be8d
commit 4882648dad
2 changed files with 12 additions and 0 deletions
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4
crypto/ecdsa.c
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@ -1065,6 +1065,10 @@ int ecdsa_recover_pub_from_sig(const ecdsa_curve *curve, uint8_t *pub_key,
scalar_multiply(curve, &e, &cp2);
// cp = (s * r^-1 * k - digest * r^-1) * G = Pub
point_add(curve, &cp2, &cp);
// The point at infinity is not considered to be a valid public key.
if (point_is_infinity(&cp)) {
return 1;
}
pub_key[0] = 0x04;
bn_write_be(&cp.x, pub_key + 1);
bn_write_be(&cp.y, pub_key + 33);

8
crypto/tests/test_check.c
View File

@ -3574,6 +3574,14 @@ static void test_ecdsa_recover_pub_from_sig_helper(int (
"0490d2bd2e9a564d6e1d8324fc6ad00aa4ae597684ecf4abea58bdfe7287ea4fa729"
"68c2e5b0b40999ede3d7898d94e82c3f8dc4536a567a4bd45998c826a4c4b2"),
65);
// The point at infinity is not considered to be a valid public key.
res = ecdsa_recover_pub_from_sig_fn(
curve, pubkey,
fromhex(
"220cf4c7b6d568f2256a8c30cc1784a625a28c3627dac404aa9a9ecd08314ec81a88"
"828f20d69d102bab5de5f6ee7ef040cb0ff7b8e1ba3f29d79efb5250f47d"),
digest, 0);
ck_assert_int_eq(res, 1);
memcpy(
digest,