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Add ecdsa_uncompress_pubkey()

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Code based on @Arachnid's PR, but has more strict checks
This commit is contained in:
Alex Beregszaszi 2016-05-17 18:11:31 +01:00
parent d68906ec4e
commit 7d68a6ee17
2 changed files with 22 additions and 0 deletions
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21
ecdsa.c
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@ -815,6 +815,27 @@ void ecdsa_get_public_key65(const ecdsa_curve *curve, const uint8_t *priv_key, u
MEMSET_BZERO(&k, sizeof(k));
}
int ecdsa_uncompress_pubkey(const ecdsa_curve *curve, const uint8_t *pub_key, uint8_t *uncompressed)
{
if (pub_key[0] == 2 || pub_key[0] == 3) {
bignum256 x, y;
bn_read_be(pub_key + 1, &x);
// uncompress_coords will check for pub_key[0] & 1
uncompress_coords(curve, pub_key[0], &x, &y);
uncompressed[0] = 4;
memcpy(uncompressed + 1, pub_key + 1, 32);
bn_write_be(&y, uncompressed + 33);
return 1;
} else if (pub_key[0] == 4) {
memcpy(uncompressed, pub_key, 65);
return 1;
}
return 0;
}
void ecdsa_get_pubkeyhash(const uint8_t *pub_key, uint8_t *pubkeyhash)
{
uint8_t h[32];

1
ecdsa.h
View File

@ -58,6 +58,7 @@ int point_is_equal(const curve_point *p, const curve_point *q);
int point_is_negative_of(const curve_point *p, const curve_point *q);
void scalar_multiply(const ecdsa_curve *curve, const bignum256 *k, curve_point *res);
void uncompress_coords(const ecdsa_curve *curve, uint8_t odd, const bignum256 *x, bignum256 *y);
int ecdsa_uncompress_pubkey(const ecdsa_curve *curve, const uint8_t *pub_key, uint8_t *uncompressed);
int ecdsa_sign(const ecdsa_curve *curve, const uint8_t *priv_key, const uint8_t *msg, uint32_t msg_len, uint8_t *sig, uint8_t *pby);
int ecdsa_sign_double(const ecdsa_curve *curve, const uint8_t *priv_key, const uint8_t *msg, uint32_t msg_len, uint8_t *sig, uint8_t *pby);