Encrypt a home directory with ECryptfs
The option to encrypt the disk or a partition is usually performed during system installation.
But instead of encrypting the entire disk, there is the option to encrypt just the user's home directory. Maybe it doesn't offer the same level of security, but for some users it may be enough.
The encrypted home directory will not require any extra passwords besides the user login password, as is normally done. Even if someone has access to the system as root, and changes the user's password, they won't be able to access the encrypted files - it is necessary to know the original password.
For full information, see ECryptfs.
Install the necessary software. As this is masked software, it is necessary to unmask it, see the unmasking a package article on how to do that. The USE=suid flag may need setting on sys-fs/ecryptfs-utils. Then emege sys-fs/ecryptfs-utils:
emerge --ask ecryptfs-utils
Restart the computer. At the login screen, do not log in.
Open a new tty, for example: Ctrl + Alt + F2.
Log in with the root user.
Activate the module:
Migrate user's home directory to an encrypted home directory. It will prompt for the user's password:
ecryptfs-migrate-home -u <USERNAME>
Switch to the daily user. It will prompt for the user's password again:
Go to home folder:
Run the mount wrapper script. Use the user password when prompted:
Unwrap an eCryptfs mount passphrase. Enter user password, again:
Run the unmount wrapper script:
If logging in as root again, in the home directory there will be a copy of user's directory followed by "." and some characters. It's a backup, to restore personal files if something goes wrong. When the whole process is done and it's working, that directory may be deleted.
To allow the encrypted home directory to be mounted automatically on login, proceed as follows.
Make a backup of the "/etc/pam.d/system-auth":
cp /etc/pam.d/system-auth /etc/pam.d/system-auth.ori
Add two lines to the file.
Compare the differences, and see which lines have been added:
diff -u /etc/pam.d/system-auth.ori /etc/pam.d/system-auth
--- /etc/pam.d/system-auth.ori 2022-08-21 19:02:30.070080014 -0300 +++ /etc/pam.d/system-auth 2022-08-21 19:03:52.649811213 -0300 @@ -2,6 +2,7 @@ auth requisite pam_faillock.so preauth auth [success=1 default=ignore] pam_unix.so nullok try_first_pass auth [default=die] pam_faillock.so authfail +auth optional pam_ecryptfs.so unwrap account required pam_unix.so account required pam_faillock.so password required pam_passwdqc.so config=/etc/security/passwdqc.conf @@ -9,3 +10,4 @@ session required pam_limits.so session required pam_env.so session required pam_unix.so +session optional pam_ecryptfs.so unwrap
Save and exit. Restart and log in normally with username.