[Pkg-bitcoin-commits] [libsecp256k1] 22/37: add pubkey prefix constants to include/secp256k1.h

[Jonas Smedegaard]

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js pushed a commit to branch master
in repository libsecp256k1.

commit bc61b91aca21a103514c5d47a20f9c7b84d5feb5
Author: Andrew Poelstra <apoelstra at wpsoftware.net>
Date:   Thu Jun 8 01:17:59 2017 +0000

    add pubkey prefix constants to include/secp256k1.h
---
 include/secp256k1.h |  7 +++++++
 src/eckey_impl.h    | 11 ++++++-----
 2 files changed, 13 insertions(+), 5 deletions(-)

diff --git a/include/secp256k1.h b/include/secp256k1.h
index fc4c5ce..2a27515 100644
--- a/include/secp256k1.h
+++ b/include/secp256k1.h
@@ -159,6 +159,13 @@ typedef int (*secp256k1_nonce_function)(
 #define SECP256K1_EC_COMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION)
 #define SECP256K1_EC_UNCOMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION)
 
+/** Prefix byte used to tag various encoded curvepoints for specific purposes */
+#define SECP256K1_TAG_PUBKEY_EVEN 0x02
+#define SECP256K1_TAG_PUBKEY_ODD 0x03
+#define SECP256K1_TAG_PUBKEY_UNCOMPRESSED 0x04
+#define SECP256K1_TAG_PUBKEY_HYBRID_EVEN 0x06
+#define SECP256K1_TAG_PUBKEY_HYBRID_ODD 0x07
+
 /** Create a secp256k1 context object.
  *
  *  Returns: a newly created context object.
diff --git a/src/eckey_impl.h b/src/eckey_impl.h
index ce38071..661d745 100644
--- a/src/eckey_impl.h
+++ b/src/eckey_impl.h
@@ -15,16 +15,17 @@
 #include "ecmult_gen.h"
 
 static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char *pub, size_t size) {
-    if (size == 33 && (pub[0] == 0x02 || pub[0] == 0x03)) {
+    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] == 0x03);
+        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)) {
         secp256k1_fe x, y;
         if (!secp256k1_fe_set_b32(&x, pub+1) || !secp256k1_fe_set_b32(&y, pub+33)) {
             return 0;
         }
         secp256k1_ge_set_xy(elem, &x, &y);
-        if ((pub[0] == 0x06 || pub[0] == 0x07) && secp256k1_fe_is_odd(&y) != (pub[0] == 0x07)) {
+        if ((pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_EVEN || pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD) &&
+            secp256k1_fe_is_odd(&y) != (pub[0] == SECP256K1_TAG_PUBKEY_HYBRID_ODD)) {
             return 0;
         }
         return secp256k1_ge_is_valid_var(elem);
@@ -42,10 +43,10 @@ static int secp256k1_eckey_pubkey_serialize(secp256k1_ge *elem, unsigned char *p
     secp256k1_fe_get_b32(&pub[1], &elem->x);
     if (compressed) {
         *size = 33;
-        pub[0] = 0x02 | (secp256k1_fe_is_odd(&elem->y) ? 0x01 : 0x00);
+        pub[0] = secp256k1_fe_is_odd(&elem->y) ? SECP256K1_TAG_PUBKEY_ODD : SECP256K1_TAG_PUBKEY_EVEN;
     } else {
         *size = 65;
-        pub[0] = 0x04;
+        pub[0] = SECP256K1_TAG_PUBKEY_UNCOMPRESSED;
         secp256k1_fe_get_b32(&pub[33], &elem->y);
     }
     return 1;

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