On Thu, Dec 21, 2000 at 02:01:19AM +0000, Al Snell wrote:
> On Tue, 19 Dec 2000, Manuel Bouyer wrote:
> 
> Very few cryptosystems have any affect whatsoever on the file sizes! It
> will be easy to just call a function on each 512-byte block as it goes
> to/from the disk... it'll add a few microseconds of latency to disk access
> and slightly increase the CPU usage during disk I/O, but since disk
> bandwidth is so low, I doubt it'll be significant unless the cypher is
> naff - and there are crypto algorithms that keep the security in a large
> key initialisation ("login") time, during which large look up tables are
> created, while the actual encryption/decryption runs very fast.

The best cryptography software I used does create different lenght results
each time the same block is encrypted, if there exists such encryption
systems that can be used for filesystems the size would vary but could be
estimated