Function json_checkmessage

lightningd/signmessage.c:151–235

}

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) {
		struct jsonrpc_request *req;