Function decrypt_hsm

tools/lightning-hsmtool.c:115–166

Legacy function - only works with binary encrypted format */

/* Legacy function - only works with binary encrypted format */
static void decrypt_hsm(const char *hsm_secret_path)
{
	int fd;
	struct hsm_secret *hsms;
	const char *dir, *backup;

	/* Check if it's a format we can decrypt */
	u8 *contents = grab_file_raw(tmpctx, hsm_secret_path);
	if (!contents)
		err(EXITCODE_ERROR_HSM_FILE, "Reading hsm_secret");

	enum hsm_secret_type type = detect_hsm_secret_type(contents, tal_bytelen(contents));

	if (type != HSM_SECRET_ENCRYPTED) {
		errx(ERROR_USAGE, "decrypt command only works on legacy encrypted binary format (73 bytes).\n"
		                  "Current file is: %s\n"
		                  "For mnemonic formats, use the generatehsm command to create a new hsm_secret instead.",
		                  format_type_name(type));
	}

	/* Load the hsm_secret */
	hsms = load_hsm_secret(tmpctx, hsm_secret_path);

	dir = path_dirname(NULL, hsm_secret_path);
	backup = path_join(dir, dir, "hsm_secret.backup");

	/* Create a backup file, "just in case". */
	rename(hsm_secret_path, backup);
	fd = open(hsm_secret_path, O_CREAT|O_EXCL|O_WRONLY, 0400);
	if (fd < 0)
		err(EXITCODE_ERROR_HSM_FILE, "Could not open new hsm_secret");

	if (!write_all(fd, hsms->secret_data, tal_bytelen(hsms->secret_data))) {
		unlink_noerr(hsm_secret_path);
		close(fd);
		rename("hsm_secret.backup", hsm_secret_path);
		err(EXITCODE_ERROR_HSM_FILE,
		    "Failure writing plaintext seed to hsm_secret.");
	}

	/* Be as paranoïd as in hsmd with the file state on disk. */
	if (!ensure_hsm_secret_exists(fd, hsm_secret_path)) {
		unlink_noerr(hsm_secret_path);
		rename(backup, hsm_secret_path);
		errx(EXITCODE_ERROR_HSM_FILE,
		    "Could not ensure hsm_secret existence.");
	}
	unlink_noerr(backup);
	tal_free(dir);

	printf("Successfully decrypted hsm_secret, be careful now :-).\n");
}

/* Legacy function - only works with binary plain format */
static void encrypt_hsm(const char *hsm_secret_path)