More security for transport over the Internet. Add feature for encrypt backup

[frekele]

Add support for encrypt openssl backup files.
More security for transport over the Internet.

Encrypt and decrypt:

# openssl aes-128-cbc -salt -in file -out file.aes
# openssl aes-128-cbc -d -salt -in file.aes -out file

Note that the file can of course be a tar archive.
tar and encrypt a whole directory

# tar -cf - directory | openssl aes-128-cbc -salt -out directory.tar.aes      # Encrypt
# openssl aes-128-cbc -d -salt -in directory.tar.aes | tar -x -f -            # Decrypt

tar zip and encrypt a whole directory

# tar -zcf - directory | openssl aes-128-cbc -salt -out directory.tar.gz.aes  # Encrypt
# openssl aes-128-cbc -d -salt -in directory.tar.gz.aes | tar -xz -f -        # Decrypt

Use -k mysecretpassword after aes-128-cbc to avoid the interactive password request. However note that this is highly insecure.
Use aes-256-cbc instead of aes-128-cbc to get even stronger encryption. This uses also more CPU.

[pascalandy]

+1