frost/secp256k1-zkp
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add pubkey prefix constants to include/secp256k1.h

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Andrew Poelstra 2017-06-08 01:17:59 +00:00
parent 84973d393a
commit bc61b91aca
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GPG Key ID: 4FACF08041655A68
2 changed files with 13 additions and 5 deletions
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7
include/secp256k1.h
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@ -159,6 +159,13 @@ typedef int (*secp256k1_nonce_function)(
#define SECP256K1_EC_COMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION) #define SECP256K1_EC_COMPRESSED (SECP256K1_FLAGS_TYPE_COMPRESSION | SECP256K1_FLAGS_BIT_COMPRESSION)
#define SECP256K1_EC_UNCOMPRESSED (SECP256K1_FLAGS_TYPE_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. /** Create a secp256k1 context object.
* *
* Returns: a newly created context object. * Returns: a newly created context object.

11
src/eckey_impl.h
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@ -15,16 +15,17 @@
#include "ecmult_gen.h" #include "ecmult_gen.h"
static int secp256k1_eckey_pubkey_parse(secp256k1_ge *elem, const unsigned char *pub, size_t size) { 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; 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)) { } else if (size == 65 && (pub[0] == 0x04 || pub[0] == 0x06 || pub[0] == 0x07)) {
secp256k1_fe x, y; secp256k1_fe x, y;
if (!secp256k1_fe_set_b32(&x, pub+1) || !secp256k1_fe_set_b32(&y, pub+33)) { if (!secp256k1_fe_set_b32(&x, pub+1) || !secp256k1_fe_set_b32(&y, pub+33)) {
return 0; return 0;
} }
secp256k1_ge_set_xy(elem, &x, &y); 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 0;
} }
return secp256k1_ge_is_valid_var(elem); 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); secp256k1_fe_get_b32(&pub[1], &elem->x);
if (compressed) { if (compressed) {
*size = 33; *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 { } else {
*size = 65; *size = 65;
pub[0] = 0x04; pub[0] = SECP256K1_TAG_PUBKEY_UNCOMPRESSED;
secp256k1_fe_get_b32(&pub[33], &elem->y); secp256k1_fe_get_b32(&pub[33], &elem->y);
} }
return 1; return 1;