Added check-future-secret.

Author: ksedgwic

contrib/remote_hsmd/NOTES.md

@@ -64,6 +64,9 @@ Some popular tests:
 
     # sign-mutual-close
     export THETEST=tests/test_closing.py::test_closing
+    
+    # check-future-secret
+    export THETEST=tests/test_connection.py::test_dataloss_protection
 
 rust-lightning-signer
 ----------------------------------------------------------------

contrib/remote_hsmd/TODO.md

@@ -26,13 +26,13 @@ COMPLETE		proxy_stat proxy_handle_sign_delayed_payment_to_us
 COMPLETE		proxy_stat proxy_handle_sign_penalty_to_us
 COMPLETE		proxy_stat proxy_handle_sign_commitment_tx
 COMPLETE		proxy_stat proxy_handle_sign_mutual_close_tx
+COMPLETE		proxy_stat proxy_handle_check_future_secret
 
 PARTIAL (-P2SH)	proxy_stat proxy_handle_sign_withdrawal_tx
 
 MARSHALED		proxy_stat proxy_init_hsm
 MARSHALED		proxy_stat proxy_handle_sign_message
 MARSHALED		proxy_stat proxy_handle_cannouncement_sig
-MARSHALED		proxy_stat proxy_handle_check_future_secret
 ```
 
 Improvements

contrib/remote_hsmd/hsmd.c

@@ -1364,10 +1364,8 @@ static struct io_plan *handle_check_future_secret(struct io_conn *conn,
 						  struct client *c,
 						  const u8 *msg_in)
 {
-	struct secret channel_seed;
-	struct sha256 shaseed;
 	u64 n;
-	struct secret secret, suggested;
+	struct secret suggested;
 
 	if (!fromwire_hsm_check_future_secret(msg_in, &n, &suggested))
 		return bad_req(conn, c, msg_in);
@@ -1383,25 +1381,11 @@ static struct io_plan *handle_check_future_secret(struct io_conn *conn,
 		return bad_req_fmt(conn, c, msg_in,
 				   "proxy_%s error: %s", __FUNCTION__,
 				   proxy_last_message());
-	g_proxy_impl = PROXY_IMPL_MARSHALED;
-
-	/* FIXME - REPLACE BELOW W/ REMOTE RETURN */
-
-	get_channel_seed(&c->id, c->dbid, &channel_seed);
-	if (!derive_shaseed(&channel_seed, &shaseed))
-		return bad_req_fmt(conn, c, msg_in, "bad derive_shaseed");
-
-	if (!per_commit_secret(&shaseed, &secret, n))
-		return bad_req_fmt(conn, c, msg_in,
-				   "bad commit secret #%"PRIu64, n);
+	g_proxy_impl = PROXY_IMPL_COMPLETE;
 
-	/*~ Note the special secret_eq_consttime: we generate foo_eq for many
-	 * types using ccan/structeq, but not 'struct secret' because any
-	 * comparison risks leaking information about the secret if it is
-	 * timing dependent. */
 	return req_reply(conn, c,
 			 take(towire_hsm_check_future_secret_reply(NULL,
-				   secret_eq_consttime(&secret, &suggested))));
+								   correct)));
 }
 
 /* This is used by closingd to sign off on a mutual close tx. */