tarmill project is a tar file compression/encryption program.
This is a program to compress and encrypt tar archives. Each archive member is handled separately, so damage in the middle of the archive does not render the rest of the archive unusable - it will be possible to resume at the next readable member header. Compressed and encrypted
archives are still valid tar files, any well-behaved tar should be able to list (but not extract) them.
tarmill acts as a filter, it takes a tar archive on standard input and produces a tar archive on standard output. Use it in backup scripts in conjunction with tar, like in this definition for the "tob" package:
BACKUPCMD='tar -c -S -T $FILELIST -f - |
tarmill -F1500 -m8M -C6M zip 3 list encrypt /etc/tob/key >$BACKUPDEV'
RESTORECMD='tarmill decrypt /etc/tob/key unzip list