I decided to encrypt some of my directories both on internal hard disks and external hard disks. One of the reasons for encrypting on an external hard disk is so that I can keep an offsite copy of my files without worrying that somebody who gets hold of the disk can read the files.
The best guide I found was the ArchWiki one. It's succinct but all that is essential is there.
For openSUSE, the kernel is recent enough but the stock e2fsprogs 1.42 package is not. You'll need to download 1.43 sources and compile. These utilities must be the 1.43 version: tune2fs (for enabling the encrypt feature), e2fsck (to deal with the new feature), and of course e4crypt (for adding a key to the kernel keychain). The other utilities can be the stock ones.
A short word about keys. When you add a key with e4crypt, it will attempt to use the key with all filesystems for which the password matches. So if you have been using the same password on several filesystems, all the matching ones will be unlocked.
If you have unlocked a directory and then delete the key from the keychain with keyctl, the encrypted directories on the mounted filesystem remain unlocked. Access will be lost only when you umount.
When assigning policies to directories, you need to use the one for the filesystem it resides on. To avoid confusion if possible you should clear the kernel keychain, and then e4crypt add_key for the target filesystem, then use the corresponding descriptor. Otherwise if you use the descriptor for another filesystem by accident, you will not be able to read the directory when the other filesystem has not been unlocked.
These commands of keyctl will be of most use: show, clear, new_session. You might also want to specify the keyring. Most likely it's @us.
The best guide I found was the ArchWiki one. It's succinct but all that is essential is there.
For openSUSE, the kernel is recent enough but the stock e2fsprogs 1.42 package is not. You'll need to download 1.43 sources and compile. These utilities must be the 1.43 version: tune2fs (for enabling the encrypt feature), e2fsck (to deal with the new feature), and of course e4crypt (for adding a key to the kernel keychain). The other utilities can be the stock ones.
A short word about keys. When you add a key with e4crypt, it will attempt to use the key with all filesystems for which the password matches. So if you have been using the same password on several filesystems, all the matching ones will be unlocked.
If you have unlocked a directory and then delete the key from the keychain with keyctl, the encrypted directories on the mounted filesystem remain unlocked. Access will be lost only when you umount.
When assigning policies to directories, you need to use the one for the filesystem it resides on. To avoid confusion if possible you should clear the kernel keychain, and then e4crypt add_key for the target filesystem, then use the corresponding descriptor. Otherwise if you use the descriptor for another filesystem by accident, you will not be able to read the directory when the other filesystem has not been unlocked.
These commands of keyctl will be of most use: show, clear, new_session. You might also want to specify the keyring. Most likely it's @us.
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