[sllug-members]: Encrypted backup tapes

[Andrew Johnson]

> My experience with a small tar file of text files files was that the
> size of the tar file gzipped and then encrypted was the same size as the
> tarfile just encrypted. At the time it made sense to me because the
> encryption routine needs to get the highest entropy possible, and
> encrypting plain text starts with low entropy.
>
> Does this hold true for larger files?

No, it shouldn't.  Encryption shouldn't change the size of a file
much, just add a fixed overhead.  At least if you leave the result of
the encryption in a binary format.

On the other hand, if you compress a text file, then encrypt and
ascii-armor it, the ascii-armor will probably just about cancel out
the compression.