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Lagrang3Lagrang3
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add signmessagewithkey RPC
signmessagewithkey: allows to sign a message with a key associated with one bitcoin address in our wallet. Changelog-Added: add a new rpc command signmessagewithkey to sign input messages with keys from our wallet. Signed-off-by: Lagrang3 <lagrang3@protonmail.com>
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‎contrib/msggen/msggen/schema.json

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@@ -32794,6 +32794,91 @@
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}
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]
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},
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"lightning-signmessagewithkey.json": {
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"$schema": "../rpc-schema-draft.json",
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"type": "object",
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"rpc": "signmessagewithkey",
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"title": "Command to create a signature using a key from the wallet",
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"description": [
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"The **signmessagewithkey** RPC command creates a digital signature of *message* using the key associated with the address provided in the input.",
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"The signature scheme follows the BIP137 specification."
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],
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"added": "v25.05",
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"request": {
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"required": [
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"message",
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"address"
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],
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"additionalProperties": false,
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"properties": {
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"message": {
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"type": "string",
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"description": [
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"Less than 65536 characters long message to be signed by the node."
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]
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},
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"address": {
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"type": "string",
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"description": [
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"A Bitcoin accepted type address for lookup in the list of addresses issued to date.",
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"Only P2WPKH type addresses are supported"
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]
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}
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}
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},
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"response": {
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"required": [
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"address",
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"keyidx",
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"pubkey",
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"signature",
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"base64"
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],
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"additionalProperties": false,
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"properties": {
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"address": {
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"type": "string",
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"description": [
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"The bitcoin address used for signing."
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]
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},
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"keyidx": {
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"type": "u64",
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"description": [
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"The key index of the address requested."
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]
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},
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"pubkey": {
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"type": "pubkey",
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"description": [
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"The public key associated with the bitcoin address provided."
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]
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},
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"signature": {
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"type": "hex",
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"description": [
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"The signature."
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]
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},
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"base64": {
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"type": "string",
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"description": [
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"The signature encoded in base64."
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]
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}
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}
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},
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"author": [
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"Lagrang3 <<lagrang3@protonmail.com>> is mainly responsible."
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],
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"see_also": [
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"lightning-checkmessagewithkey(7)"
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],
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"resources": [
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"Main web site: <https://github.com/ElementsProject/lightning>"
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],
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"examples": []
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},
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"lightning-signpsbt.json": {
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"$schema": "../rpc-schema-draft.json",
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"type": "object",

‎doc/schemas/lightning-signmessagewithkey.json

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{
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"$schema": "../rpc-schema-draft.json",
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"type": "object",
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"rpc": "signmessagewithkey",
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"title": "Command to create a signature using a key from the wallet",
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"description": [
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"The **signmessagewithkey** RPC command creates a digital signature of *message* using the key associated with the address provided in the input.",
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"The signature scheme follows the BIP137 specification."
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],
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"added": "v25.05",
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"request": {
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"required": [
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"message",
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"address"
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],
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"additionalProperties": false,
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"properties": {
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"message": {
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"type": "string",
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"description": [
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"Less than 65536 characters long message to be signed by the node."
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]
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},
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"address": {
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"type": "string",
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"description": [
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"A Bitcoin accepted type address for lookup in the list of addresses issued to date.",
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"Only P2WPKH type addresses are supported"
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]
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}
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}
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},
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"response": {
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"required": [
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"address",
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"keyidx",
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"pubkey",
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"signature",
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"base64"
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],
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"additionalProperties": false,
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"properties": {
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"address": {
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"type": "string",
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"description": [
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"The bitcoin address used for signing."
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]
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},
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"keyidx": {
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"type": "u64",
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"description": [
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"The key index of the address requested."
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]
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},
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"pubkey": {
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"type": "pubkey",
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"description": [
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"The public key associated with the bitcoin address provided."
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]
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},
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"signature": {
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"type": "hex",
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"description": [
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"The signature."
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]
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},
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"base64": {
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"type": "string",
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"description": [
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"The signature encoded in base64."
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]
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}
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}
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},
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"author": [
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"Lagrang3 <<lagrang3@protonmail.com>> is mainly responsible."
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],
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"see_also": [
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"lightning-checkmessagewithkey(7)"
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],
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"resources": [
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"Main web site: <https://github.com/ElementsProject/lightning>"
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],
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"examples": [
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]
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}
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‎wallet/walletrpc.c

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@@ -4,6 +4,7 @@
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#include <ccan/array_size/array_size.h>
55
#include <ccan/cast/cast.h>
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#include <common/addr.h>
7+
#include <common/base64.h>
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#include <common/bech32.h>
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#include <common/configdir.h>
910
#include <common/json_command.h>
@@ -1066,3 +1067,121 @@ static const struct json_command sendpsbt_command = {
10661067
};
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10681069
AUTODATA(json_command, &sendpsbt_command);
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static struct command_result *
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json_signmessagewithkey(struct command *cmd, const char *buffer,
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const jsmntok_t *obj UNNEEDED, const jsmntok_t *params)
1074+
{
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/* decoding the address */
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const u8 *scriptpubkey;
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const char *message;
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/* from wallet BIP32 */
1080+
struct pubkey pubkey;
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if (!param(
1083+
cmd, buffer, params,
1084+
p_req("message", param_string, &message),
1085+
p_req("address", param_bitcoin_address, &scriptpubkey),
1086+
NULL))
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return command_param_failed();
1088+
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const size_t script_len = tal_bytelen(scriptpubkey);
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/* FIXME: we already had the address from the input */
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char *addr;
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addr = encode_scriptpubkey_to_addr(tmpctx, chainparams, scriptpubkey);
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1095+
if (!is_p2wpkh(scriptpubkey, script_len, NULL)) {
1096+
/* FIXME add support for BIP 322 */
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return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
1098+
"address %s is not p2wpkh and "
1099+
"it is not supported for signing",
1100+
addr);
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}
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u32 keyidx;
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/* loop over all generated keys, find a matching key */
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/* FIXME: alternatively, can we use the our_addresses hash table?
1107+
*struct script_with_len *key;
1108+
*struct wallet_address *addr =
1109+
* wallet_address_htable_get(cmd->ld->wallet->our_addresses, key);
1110+
*/
1111+
struct issued_address_type *listaddrtypes =
1112+
wallet_list_addresses(tmpctx, cmd->ld->wallet, 1, NULL);
1113+
for (size_t i = 0; i < tal_count(listaddrtypes); i++) {
1114+
if (listaddrtypes[i].keyidx == BIP32_INITIAL_HARDENED_CHILD) {
1115+
break;
1116+
}
1117+
bip32_pubkey(cmd->ld, &pubkey, listaddrtypes[i].keyidx);
1118+
char *out_p2wpkh = "";
1119+
char *out_p2tr = "";
1120+
if (listaddrtypes[i].addrtype == ADDR_BECH32 ||
1121+
listaddrtypes[i].addrtype == ADDR_ALL) {
1122+
u8 *redeemscript_p2wpkh;
1123+
out_p2wpkh = encode_pubkey_to_addr(
1124+
cmd, &pubkey, ADDR_BECH32, &redeemscript_p2wpkh);
1125+
if (!out_p2wpkh) {
1126+
abort();
1127+
}
1128+
}
1129+
if (listaddrtypes[i].addrtype == ADDR_P2TR ||
1130+
listaddrtypes[i].addrtype == ADDR_ALL) {
1131+
out_p2tr =
1132+
encode_pubkey_to_addr(cmd, &pubkey, ADDR_P2TR,
1133+
/* out_redeemscript */ NULL);
1134+
if (!out_p2tr) {
1135+
abort();
1136+
}
1137+
}
1138+
1139+
if (streq(addr, out_p2wpkh) || streq(addr, out_p2tr)) {
1140+
keyidx = listaddrtypes[i].keyidx;
1141+
break;
1142+
}
1143+
}
1144+
1145+
/* wire to hsmd a sign request */
1146+
u8 *msg = towire_hsmd_sign_message_with_key(
1147+
cmd, tal_dup_arr(tmpctx, u8, (u8 *)message, strlen(message), 0),
1148+
keyidx);
1149+
if (!wire_sync_write(cmd->ld->hsm_fd, take(msg))) {
1150+
fatal("Could not write sign_with_key to HSM: %s",
1151+
strerror(errno));
1152+
}
1153+
1154+
/* read form hsmd a sign reply */
1155+
msg = wire_sync_read(cmd, cmd->ld->hsm_fd);
1156+
1157+
int recid;
1158+
u8 sig[65];
1159+
secp256k1_ecdsa_recoverable_signature rsig;
1160+
1161+
if (!fromwire_hsmd_sign_message_with_key_reply(msg, &rsig)) {
1162+
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
1163+
"HSM gave bad sign_with_key_reply %s",
1164+
tal_hex(tmpctx, msg));
1165+
}
1166+
1167+
secp256k1_ecdsa_recoverable_signature_serialize_compact(
1168+
secp256k1_ctx, sig + 1, &recid, &rsig);
1169+
/* this is the header value for P2WPKH specified in BIP137 */
1170+
sig[0] = recid + 39;
1171+
1172+
struct json_stream *response;
1173+
response = json_stream_success(cmd);
1174+
json_add_string(response, "address", addr);
1175+
json_add_u32(response, "keyidx", keyidx);
1176+
json_add_pubkey(response, "pubkey", &pubkey);
1177+
json_add_hex(response, "signature", sig, sizeof(sig));
1178+
json_add_string(response, "base64",
1179+
b64_encode(tmpctx, sig, sizeof(sig)));
1180+
return command_success(cmd, response);
1181+
}
1182+
1183+
static const struct json_command signmessagewithkey_command = {
1184+
"signmessagewithkey",
1185+
json_signmessagewithkey
1186+
};
1187+
AUTODATA(json_command, &signmessagewithkey_command);

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