Merge #562: Make use of TAG_PUBKEY constants in secp256k1_eckey_pubkey_parse

d3cb1f9 Make use of TAG_PUBKEY constants in secp256k1_eckey_pubkey_parse (Ben Woosley)

Pull request description:

  This results in more self-documenting code.

  Constants defined here:
  https://github.com/bitcoin-core/secp256k1/blob/1e6f1f5ad5e7f1e3ef79313ec02023902bf8175c/include/secp256k1.h#L175-L180

Tree-SHA512: 2026103c487a5ebdea9a2f5ec2be96d74e38d5b2269b4df11e354bb54aba2925b47c3185f530205019840b00fc3501121acfa5234faf1d095d71777826414f69

Author: gmaxwell

src/eckey_impl.h

@@ -18,7 +18,7 @@ static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char
     if (size == 33 && (pub[0] == SECP256K1_TAG_PUBKEY_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_ODD)) {
         secp256k1_fe x;
         return secp256k1_fe_set_b32(&x, pub+1) && secp256k1_ge_set_xo_var(elem, &x, pub[0] == SECP256K1_TAG_PUBKEY_ODD);
-    } else if (size == 65 && (pub[0] == 0x04 || pub[0] == 0x06 || pub[0] == 0x07)) {
+    } else if (size == 65 && (pub[0] == SECP256K1_TAG_PUBKEY_UNCOMPRESSED || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
         secp256k1_fe x, y;
         if (!secp256k1_fe_set_b32(&x, pub+1) || !secp256k1_fe_set_b32(&y, pub+33)) {
             return 0;