Function payer_key_tweak

common/bolt12_merkle.c:224–238

We use the SHA(pubkey | publictweak); so reader cannot figure out the * tweak and derive the base key */

/* We use the SHA(pubkey | publictweak); so reader cannot figure out the
 * tweak and derive the base key */
void payer_key_tweak(const struct point32 *bolt12,
		     const u8 *publictweak, size_t publictweaklen,
		     struct sha256 *tweak)
{
	u8 rawkey[32];
	struct sha256_ctx sha;

	secp256k1_xonly_pubkey_serialize(secp256k1_ctx, rawkey, &bolt12->pubkey);
	sha256_init(&sha);
	sha256_update(&sha, rawkey, sizeof(rawkey));
	sha256_update(&sha,
		      memcheck(publictweak, publictweaklen),
		      publictweaklen);
	sha256_done(&sha, tweak);
}