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core-lightning/lightningd/signmessage.c
Rusty Russell 684ed4231f common/wireaddr: don't include lightningd/lightningd. 
common should not include specific per-daemon files.  Turns out this
caused a lot of indirect includes to be exposed.

Signed-off-by: Rusty Russell <rusty@rustcorp.com.au>
2020-02-27 14:16:16 +10:30

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#include <common/bech32.h>
#include <common/hash_u5.h>
#include <common/json_command.h>
#include <common/json_helpers.h>
#include <common/jsonrpc_errors.h>
#include <common/param.h>
#include <common/type_to_string.h>
#include <common/utils.h>
#include <errno.h>
#include <gossipd/gen_gossip_wire.h>
#include <hsmd/gen_hsm_wire.h>
#include <lightningd/jsonrpc.h>
#include <lightningd/lightningd.h>
#include <lightningd/subd.h>
#include <string.h>
#include <wire/wire_sync.h>
/* These tables copied from zbase32 src:
* copyright 2002-2007 Zooko "Zooko" Wilcox-O'Hearn
* mailto:zooko@zooko.com
*
* Permission is hereby granted to any person obtaining a copy of this work to
* deal in this work without restriction (including the rights to use, modify,
* distribute, sublicense, and/or sell copies).
*/
static const char*const zbase32_chars="ybndrfg8ejkmcpqxot1uwisza345h769";
/* revchars: index into this table with the ASCII value of the char. The result is the value of that quintet. */
static const u8 zbase32_revchars[]={ 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 18, 255, 25, 26, 27, 30, 29, 7, 31, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 24, 1, 12, 3, 8, 5, 6, 28, 21, 9, 10, 255, 11, 2, 16, 13, 14, 4, 22, 17, 19, 255, 20, 15, 0, 23, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, 255, };
static const char *to_zbase32(const tal_t *ctx, const u8 *msg, size_t srclen)
{
size_t outlen;
char *out = tal_arr(ctx, char, (srclen * 8 + 4) / 5 + 1);
outlen = 0;
if (!bech32_convert_bits((uint8_t *)out, &outlen, 5, msg, srclen, 8, true))
return tal_free(out);
assert(outlen < tal_bytelen(out));
for (size_t i = 0; i < outlen; i++)
out[i] = zbase32_chars[(unsigned)out[i]];
out[outlen] = '\0';
return out;
}
static const u8 *from_zbase32(const tal_t *ctx, const char *msg)
{
u5 *u5arr;
u8 *u8arr;
size_t len;
u5arr = tal_arr(tmpctx, u5, strlen(msg));
for (size_t i = 0; i < tal_bytelen(u5arr); i++) {
u5arr[i] = zbase32_revchars[(unsigned char)msg[i]];
if (u5arr[i] > 31)
return NULL;
}
u8arr = tal_arr(ctx, u8, (tal_bytelen(u5arr) * 5 + 7) / 8);
len = 0;
if (!bech32_convert_bits(u8arr, &len, 8,
u5arr, tal_bytelen(u5arr), 5, false))
return tal_free(u8arr);
assert(len == tal_bytelen(u8arr));
return u8arr;
}
static struct command_result *json_signmessage(struct command *cmd,
const char *buffer,
const jsmntok_t *obj UNNEEDED,
const jsmntok_t *params)
{
const char *message;
secp256k1_ecdsa_recoverable_signature rsig;
struct json_stream *response;
u8 sig[65], *msg;
int recid;
if (!param(cmd, buffer, params,
p_req("message", param_string, &message),
NULL))
return command_param_failed();
if (strlen(message) > 65535)
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"Message must be < 64k");
msg = towire_hsm_sign_message(NULL,
tal_dup_arr(tmpctx, u8, (u8 *)message,
strlen(message), 0));
if (!wire_sync_write(cmd->ld->hsm_fd, take(msg)))
fatal("Could not write to HSM: %s", strerror(errno));
msg = wire_sync_read(tmpctx, cmd->ld->hsm_fd);
if (!fromwire_hsm_sign_message_reply(msg, &rsig))
fatal("HSM gave bad hsm_sign_message_reply %s",
tal_hex(msg, msg));
secp256k1_ecdsa_recoverable_signature_serialize_compact(secp256k1_ctx,
sig+1, &recid,
&rsig);
response = json_stream_success(cmd);
json_add_hex(response, "signature", sig+1, sizeof(sig)-1);
sig[0] = recid;
json_add_hex(response, "recid", sig, 1);
/* From 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 */
sig[0] += 31;
json_add_string(response, "zbase",
to_zbase32(response, sig, sizeof(sig)));
return command_success(cmd, response);
}
static const struct json_command json_signmessage_cmd = {
"signmessage",
"utility",
json_signmessage,
"Create a digital signature of {message}",
};
AUTODATA(json_command, &json_signmessage_cmd);
struct command_and_node {
struct command *cmd;
struct node_id id;
};
/* Gossipd tells us if it's a known node by returning details. */
static void getnode_reply(struct subd *gossip UNUSED, const u8 *reply,
const int *fds UNUSED,
struct command_and_node *can)
{
struct gossip_getnodes_entry **nodes;
struct json_stream *response;
if (!fromwire_gossip_getnodes_reply(reply, reply, &nodes)) {
log_broken(can->cmd->ld->log,
"Malformed gossip_getnodes response %s",
tal_hex(tmpctx, reply));
nodes = NULL;
}
response = json_stream_success(can->cmd);
json_add_node_id(response, "pubkey", &can->id);
json_add_bool(response, "verified", tal_count(nodes) > 0);
was_pending(command_success(can->cmd, response));
}
static struct command_result *json_checkmessage(struct command *cmd,
const char *buffer,
const jsmntok_t *obj UNNEEDED,
const jsmntok_t *params)
{
struct pubkey *pubkey, reckey;
const u8 *u8sig;
const char *message, *zb;
secp256k1_ecdsa_recoverable_signature rsig;
struct sha256_ctx sctx = SHA256_INIT;
struct sha256_double shad;
struct json_stream *response;
if (!param(cmd, buffer, params,
p_req("message", param_string, &message),
p_req("zbase", param_string, &zb),
p_opt("pubkey", param_pubkey, &pubkey),
NULL))
return command_param_failed();
u8sig = from_zbase32(tmpctx, zb);
if (!u8sig)
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"zbase is not valid zbase32");
if (tal_bytelen(u8sig) != 65)
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"zbase is too %s",
tal_bytelen(u8sig) < 65 ? "short" : "long");
if (!secp256k1_ecdsa_recoverable_signature_parse_compact(secp256k1_ctx,
&rsig,
u8sig + 1,
u8sig[0] - 31))
return command_fail(cmd, JSONRPC2_INVALID_PARAMS,
"cannot parse zbase signature");
sha256_update(&sctx, "Lightning Signed Message:",
strlen("Lightning Signed Message:"));
sha256_update(&sctx, message, strlen(message));
sha256_double_done(&sctx, &shad);
if (!secp256k1_ecdsa_recover(secp256k1_ctx, &reckey.pubkey, &rsig,
shad.sha.u.u8)) {
response = json_stream_success(cmd);
json_add_bool(response, "verified", false);
return command_success(cmd, response);
}
/* If they didn't specify pubkey, we only accept the signature if it's
* in the graph (thus, they've signed something with it). This idea
* was stolen directly from lnd, thanks @roasbeef.
*
* FIXME: We could also look through known invoices: AFAICT you can't
* make two (different) signed messages with the same recovered key
* unless you know the secret key */
if (!pubkey) {
u8 *req;
struct command_and_node *can = tal(cmd, struct command_and_node);
node_id_from_pubkey(&can->id, &reckey);
can->cmd = cmd;
req = towire_gossip_getnodes_request(cmd, &can->id);
subd_req(cmd, cmd->ld->gossip, req, -1, 0, getnode_reply, can);
return command_still_pending(cmd);
}
response = json_stream_success(cmd);
json_add_pubkey(response, "pubkey", &reckey);
json_add_bool(response, "verified", pubkey_eq(pubkey, &reckey));
return command_success(cmd, response);
}
static const struct json_command json_checkmessage_cmd = {
"checkmessage",
"utility",
json_checkmessage,
"Verify a digital signature {zbase} of {message} signed with {pubkey}",
};
AUTODATA(json_command, &json_checkmessage_cmd);
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