@Override public OutputStream receiveUpload(String fileName, String mimeType) { FileOutputStream outStream = null; try { File file = keyService.addFile(username, keyNameField.getValue(), fileName); outStream = new FileOutputStream(file); /** SSH requires that key files only have read-write permissions for OWNER */ Set<PosixFilePermission> permissions = new HashSet<PosixFilePermission>(); permissions.add(PosixFilePermission.OWNER_READ); permissions.add(PosixFilePermission.OWNER_WRITE); Files.setPosixFilePermissions(file.toPath(), permissions); } catch (IOException e) { LOG.error("Error while setting key file permissions.", e); } return outStream; }