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hsmd: add support for signing a lightning msg from nodeid.

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Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
This commit is contained in:
Rusty Russell 2019-10-12 04:36:01 +10:30 • committed by neil saitug
parent ca53c1b699
commit 889216e0a9
2 changed files with 55 additions and 0 deletions
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8
hsmd/hsm_wire.csv
View file

@ -198,3 +198,11 @@ msgdata,hsm_check_future_secret,commitment_secret,secret,
msgtype,hsm_check_future_secret_reply,122
msgdata,hsm_check_future_secret_reply,correct,bool,
# lightningd asks us to sign a string.
msgtype,hsm_sign_message,23
msgdata,hsm_sign_message,len,u16,
msgdata,hsm_sign_message,msg,u8,len
msgtype,hsm_sign_message_reply,123
msgdata,hsm_sign_message_reply,sig,secp256k1_ecdsa_recoverable_signature,

1 # Clients should not give a bad request but not the HSM's decision to crash.
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47
hsmd/hsmd.c
View file

@ -1765,6 +1765,48 @@ static struct io_plan *handle_sign_node_announcement(struct io_conn *conn,
return req_reply(conn, c, take(reply));
}
/*~ lightningd asks us to sign a message. I tweeted the spec
* in https://twitter.com/rusty_twit/status/1182102005914800128:
*
* @roasbeef & @bitconner point out that #lnd algo is:
* zbase32(SigRec(SHA256(SHA256("Lightning Signed Message:" + msg)))).
* zbase32 from https://philzimmermann.com/docs/human-oriented-base-32-encoding.txt
* and SigRec has first byte 31 + recovery id, followed by 64 byte sig. #specinatweet
*/
static struct io_plan *handle_sign_message(struct io_conn *conn,
struct client *c,
const u8 *msg_in)
{
u8 *msg;
struct sha256_ctx sctx = SHA256_INIT;
struct sha256_double shad;
secp256k1_ecdsa_recoverable_signature rsig;
struct privkey node_pkey;
if (!fromwire_hsm_sign_message(tmpctx, msg_in, &msg))
return bad_req(conn, c, msg_in);
/* Prefixing by a known string means we'll never be convinced
* to sign some gossip message, etc. */
sha256_update(&sctx, "Lightning Signed Message:",
strlen("Lightning Signed Message:"));
sha256_update(&sctx, msg, tal_count(msg));
sha256_double_done(&sctx, &shad);
node_key(&node_pkey, NULL);
/*~ By no small coincidence, this libsecp routine uses the exact
* recovery signature format mandated by BOLT 11. */
if (!secp256k1_ecdsa_sign_recoverable(secp256k1_ctx, &rsig,
shad.sha.u.u8,
node_pkey.secret.data,
NULL, NULL)) {
return bad_req_fmt(conn, c, msg_in, "Failed to sign message");
}
return req_reply(conn, c,
take(towire_hsm_sign_message_reply(NULL, &rsig)));
}
#if DEVELOPER
static struct io_plan *handle_memleak(struct io_conn *conn,
struct client *c,
@ -1844,6 +1886,7 @@ static bool check_client_capabilities(struct client *client,
case WIRE_HSM_SIGN_COMMITMENT_TX:
case WIRE_HSM_GET_CHANNEL_BASEPOINTS:
case WIRE_HSM_DEV_MEMLEAK:
case WIRE_HSM_SIGN_MESSAGE:
return (client->capabilities & HSM_CAP_MASTER) != 0;
/*~ These are messages sent by the HSM so we should never receive them. */
@ -1865,6 +1908,7 @@ static bool check_client_capabilities(struct client *client,
case WIRE_HSM_CHECK_FUTURE_SECRET_REPLY:
case WIRE_HSM_GET_CHANNEL_BASEPOINTS_REPLY:
case WIRE_HSM_DEV_MEMLEAK_REPLY:
case WIRE_HSM_SIGN_MESSAGE_REPLY:
break;
}
return false;
@ -1945,6 +1989,8 @@ static struct io_plan *handle_client(struct io_conn *conn, struct client *c)
case WIRE_HSM_SIGN_MUTUAL_CLOSE_TX:
return handle_sign_mutual_close_tx(conn, c, c->msg_in);
case WIRE_HSM_SIGN_MESSAGE:
return handle_sign_message(conn, c, c->msg_in);
#if DEVELOPER
case WIRE_HSM_DEV_MEMLEAK:
return handle_memleak(conn, c, c->msg_in);
@ -1967,6 +2013,7 @@ static struct io_plan *handle_client(struct io_conn *conn, struct client *c)
case WIRE_HSM_CHECK_FUTURE_SECRET_REPLY:
case WIRE_HSM_GET_CHANNEL_BASEPOINTS_REPLY:
case WIRE_HSM_DEV_MEMLEAK_REPLY:
case WIRE_HSM_SIGN_MESSAGE_REPLY:
break;
}