我正在运行 Ubuntu 18.04.1 LTS，但在安装ecrypt-utils应用程序时遇到问题。请参阅下面的输出：
ubuntu@ubuntu:~$ sudo apt install ecryptfs-utils
Reading package lists... Done
Building dependency tree
Reading state information... Done
Package ecryptfs-utils is not available, but is referred to by another package.
This may mean that the package is missing, has been obsoleted, or
is only available from another source
E: Package 'ecryptfs-utils' has no installation candidate
任何帮助深表感谢。