How can I backup and encrypt with tar, split and openssl, all in one command?

Question

I often use tar to backup my stuff in 4 gigabyte chunks to a directory on a FAT32-formatted disk, as documented here.

To get that done, I use the following command: tar -cvpj /path/to/directory/ | split -d -b 4000m - "backup.tar.bz2.".

I want to encrypt these tar.bz2.* files with openssl aes-256-cbc, if possible right after making a 4 GB chunk instead of after the whole backup job. I'd like to know the proper command to do that, and how to reconstitute the archive after creation.

Solution

How about this?

tar -cvpj /path/to/directory | openssl aes-256-cbc -kfile /path/to/enc.key | split -d -b 4000m - backup.tar.bz2.enc.

To extract:

cat backup.tar.bz2.enc.* | openssl aes-256-cbc -d -kfile /path/to/enc.key | tar xvjf -

EDIT: I noticed that split has --filter.

EDIT: Since cbc chains blocks, it makes it difficult to join. I put the split after the encryption to make this easier.