fix and verify compressed argument in _eckey_pubkey_serialize calls
#300
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In several calls of the internal function `secp256k1_eckey_pubkey_serialize`, the public API flag `SECP256K1_EC_COMPRESSED` is passed, which is meant to be only used for the public function `secp256k1_ec_pubkey_serialize`. It works as intended in all of those cases (it wouldn't for `..._UNCOMPRESSED` though), but it's still kind of a type mismatch that can't be detected by the compiler. To avoid cases like this in the future, a VERIFY_CHECK is added that the `compressed` parameter needs to be either 0 or 1.
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LGTM |
| @@ -35,6 +36,8 @@ static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char | |||
| } | |||
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| static int secp256k1_eckey_pubkey_serialize(secp256k1_ge *elem, unsigned char *pub, size_t *size, int compressed) { | |||
| VERIFY_CHECK(compressed == 0 || compressed == 1); | |||
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Not sure if we want to touch this upstream file. It's also a nice goal to keep the diff to upstream minimal. Ideally, the diff to upstream would just be added modules and changes to build system, README, etc... But yeah, we've modified upstream files in the past. If we think that this is a reasonable change, we could PR it to upstream, of course.
Same is true for the modification to secp256k1.c
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We should just rebase on upstream's musig module now.
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Due to similarity to the public API function `secp256k1_ec_pubkey_serialize`, public API flags like `SECP256K1_EC_COMPRESSED` are sometimes mistakingly passed to newly proposed code (this is currently the case for several modules in secp256k1-zkp, see BlockstreamResearch/secp256k1-zkp#300). which is currently not detected. To avoid this in the future, a VERIFY_CHECK is added to check that the `compressed` argument is either 0 or 1.
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In several calls of the internal function
secp256k1_eckey_pubkey_serialize, the public API flagSECP256K1_EC_COMPRESSEDis passed, which is meant to be only used for the public functionsecp256k1_ec_pubkey_serialize. It works as intended in all of those cases (it wouldn't forSECP256K1_EC_UNCOMPRESSEDthough), but it's still kind of a type mismatch that can't be detected by the compiler. To avoid cases like this in the future, a VERIFY_CHECK is added that thecompressedparameter needs to be either 0 or 1.