From 93d3b0d12665ab9acb7e545131ad05bb93debfca Mon Sep 17 00:00:00 2001
From: Rusty Russell <rusty@rustcorp.com.au>
Date: Mon, 22 Feb 2021 12:27:57 +1030
Subject: [PATCH] doc: update BOLT quotes (to include LOW-S-standard rule).

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
---
 Makefile             | 2 +-
 bitcoin/signature.c  | 8 ++++++++
 channeld/channeld.c  | 5 +++--
 closingd/closingd.c  | 3 ++-
 openingd/dualopend.c | 6 ++++--
 openingd/openingd.c  | 7 ++++---
 6 files changed, 22 insertions(+), 9 deletions(-)

diff --git a/Makefile b/Makefile
index 41e93ceca098..41fe136f2db6 100644
--- a/Makefile
+++ b/Makefile
@@ -24,7 +24,7 @@ CCANDIR := ccan
 
 # Where we keep the BOLT RFCs
 BOLTDIR := ../lightning-rfc/
-BOLTVERSION := 7e8c478aef0d23a445845b7d297b0e804583697c
+BOLTVERSION := 01f29bf9feca66476423676365187e2175a3934b
 
 -include config.vars
 
diff --git a/bitcoin/signature.c b/bitcoin/signature.c
index afa7aeb7bbe1..17b150fe4052 100644
--- a/bitcoin/signature.c
+++ b/bitcoin/signature.c
@@ -173,6 +173,14 @@ bool check_signed_hash(const struct sha256_double *hash,
 {
 	int ret;
 
+	/* BOLT #2:
+	 *
+	 * - if `signature` is incorrect OR non-compliant with
+	 *   LOW-S-standard rule
+	 */
+	/* From the secp256k1_ecdsa_verify documentation: "To avoid
+	 * accepting malleable signatures, only ECDSA signatures in
+	 * lower-S form are accepted." */
 	ret = secp256k1_ecdsa_verify(secp256k1_ctx,
 				     signature,
 				     hash->sha.u.u8, &key->pubkey);
diff --git a/channeld/channeld.c b/channeld/channeld.c
index c8a29c0ce372..15c08aef6673 100644
--- a/channeld/channeld.c
+++ b/channeld/channeld.c
@@ -1314,7 +1314,8 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 	 *
 	 * A receiving node:
 	 *  - once all pending updates are applied:
-	 *    - if `signature` is not valid for its local commitment transaction:
+	 *    - if `signature` is not valid for its local commitment transaction
+	 *      OR non-compliant with LOW-S-standard rule...:
 	 *      - MUST fail the channel.
 	 */
 	if (!check_tx_sig(txs[0], 0, NULL, funding_wscript,
@@ -1349,7 +1350,7 @@ static void handle_peer_commit_sig(struct peer *peer, const u8 *msg)
 	/* BOLT #2:
 	 *
 	 *   - if any `htlc_signature` is not valid for the corresponding HTLC
-	 *     transaction:
+	 *     transaction OR non-compliant with LOW-S-standard rule...:
 	 *     - MUST fail the channel.
 	 */
 	for (i = 0; i < tal_count(htlc_sigs); i++) {
diff --git a/closingd/closingd.c b/closingd/closingd.c
index a090e574e758..b0d3679908e0 100644
--- a/closingd/closingd.c
+++ b/closingd/closingd.c
@@ -368,7 +368,8 @@ receive_offer(struct per_peer_state *pps,
 	 *
 	 * The receiving node:
 	 *   - if the `signature` is not valid for either variant of closing transaction
-	 *   specified in [BOLT #3](03-transactions.md#closing-transaction):
+	 *   specified in [BOLT #3](03-transactions.md#closing-transaction)
+	 *   OR non-compliant with LOW-S-standard rule...:
 	 *     - MUST fail the connection.
 	 */
 	tx = close_tx(tmpctx, chainparams, pps, channel_id,
diff --git a/openingd/dualopend.c b/openingd/dualopend.c
index 0a0d8d59679b..89cf634b6d2a 100644
--- a/openingd/dualopend.c
+++ b/openingd/dualopend.c
@@ -1722,7 +1722,8 @@ static void accepter_start(struct state *state, const u8 *oc2_msg)
 	/* BOLT #2:
 	 *
 	 * The recipient:
-	 *   - if `signature` is incorrect:
+	 *   - if `signature` is incorrect OR non-compliant with LOW-S-standard
+	 *       rule...:
 	 *     - MUST fail the channel.
 	 */
 	if (!check_tx_sig(local_commit, 0, NULL, wscript,
@@ -2203,7 +2204,8 @@ static void opener_start(struct state *state, u8 *msg)
 	/* BOLT #2:
 	 *
 	 * The recipient:
-	 *   - if `signature` is incorrect:
+	 *   - if `signature` is incorrect OR non-compliant with LOW-S-standard
+	 *     rule...:
 	 *     - MUST fail the channel.
 	 */
 	if (!check_tx_sig(local_commit, 0, NULL, wscript, &state->their_funding_pubkey,
diff --git a/openingd/openingd.c b/openingd/openingd.c
index 96ed7318615a..6ef88dd6218d 100644
--- a/openingd/openingd.c
+++ b/openingd/openingd.c
@@ -628,8 +628,8 @@ static bool funder_finalize_channel_setup(struct state *state,
 	/* BOLT #2:
 	 *
 	 * The recipient:
-	 *   - if `signature` is incorrect:
-	 *     - MUST fail the channel.
+	 *   - if `signature` is incorrect OR non-compliant with LOW-S-standard rule...:
+	 *     - MUST fail the channel
 	 */
 	/* So we create *our* initial commitment transaction, and check the
 	 * signature they sent against that. */
@@ -1004,7 +1004,8 @@ static u8 *fundee_channel(struct state *state, const u8 *open_channel_msg)
 	/* BOLT #2:
 	 *
 	 * The recipient:
-	 *   - if `signature` is incorrect:
+	 *   - if `signature` is incorrect OR non-compliant with LOW-S-standard
+	 *     rule...:
 	 *     - MUST fail the channel.
 	 */
 	local_commit = initial_channel_tx(state, &wscript, state->channel,