Function act_two_responder

connectd/handshake.c:805–885

}

static struct io_plan *act_two_responder(struct io_conn *conn,
					 struct handshake *h)
{
	size_t len;

	SUPERVERBOSE("Responder: Act 2");

	/* BOLT #8:
	 *
	 * **Sender Actions:**
	 *
	 * 1. `e = generateKey()`
	 */
	h->e = generate_key();
	SUPERVERBOSE("# e.pub=0x%s e.priv=0x%s",
		     fmt_pubkey(tmpctx, &h->e.pub),
		     tal_hexstr(tmpctx, &h->e.priv, sizeof(h->e.priv)));

	/* BOLT #8:
	 *
	 * 2. `h = SHA-256(h || e.pub.serializeCompressed())`
	 *      * The newly generated ephemeral key is accumulated into the
	 *        running handshake digest.
	 */
	sha_mix_in_key(&h->h, &h->e.pub);
	SUPERVERBOSE("# h=0x%s", tal_hexstr(tmpctx, &h->h, sizeof(h->h)));

	/* BOLT #8:
	 *
	 * 3. `ee = ECDH(e.priv, re)`
	 *      * where `re` is the ephemeral key of the initiator, which was received
	 *        during Act One
	 */
	if (!secp256k1_ecdh(secp256k1_ctx, h->ss->data, &h->re.pubkey,
			    h->e.priv.secret.data, NULL, NULL))
		return handshake_failed(conn, h);
	SUPERVERBOSE("# ss=0x%s", tal_hexstr(tmpctx, h->ss, sizeof(*h->ss)));

	/* BOLT #8:
	 *
	 * 4. `ck, temp_k2 = HKDF(ck, ee)`
	 *      * A new temporary encryption key is generated, which is
	 *       used to generate the authenticating MAC.
	 */
	hkdf_two_keys(&h->ck, &h->temp_k, &h->ck, h->ss, sizeof(*h->ss));
	SUPERVERBOSE("# ck,temp_k2=0x%s,0x%s",
		     tal_hexstr(tmpctx, &h->ck, sizeof(h->ck)),
		     tal_hexstr(tmpctx, &h->temp_k, sizeof(h->temp_k)));

	/* BOLT #8:
	 *
	 * 5. `c = encryptWithAD(temp_k2, 0, h, zero)`
	 *      * where `zero` is a zero-length plaintext
	 */
	encrypt_ad(&h->temp_k, 0, &h->h, sizeof(h->h), NULL, 0,
		   h->act2.tag, sizeof(h->act2.tag));
	SUPERVERBOSE("# c=0x%s", tal_hexstr(tmpctx, h->act2.tag, sizeof(h->act2.tag)));