Windows Rsyncrypto

[Barry J. <bar...@ww...>]

Shachar

Thanks for the quick and comprehensive response. Will look out for the new
download.

I may have a suggestion to alleviate one of the known issues - relating to
encryption strength - of making encryption rsync friendly which has been
raised (here I think?), but I need to check some assumptions before I risk
making too big a fool of myself ;-)

Am I right in thinking that, given the nature of compression (or gzip
compression at least) that repeating blocks are somewhere between unlikley
and impossible? (and if not, would it not be a useful and simple matter to
design a 'top-up' compression algorithm that eliminates repeating blocks by
replacing them with a pointer - as I believe gzip does. This could even be
recursive?).

> >Also can I ask does anyone know how well the included gzip.exe works with
in
>>combination with rsyncrypto?
>>
>It works excellent, so long as let rsyncrypto run it.

Is this because the blocks used for encryption and comression need to be
aligned to get maximum rsyncability?

> rsyncrypto runs gzip with the "rsyncable" flag. If you compress the
> files prior to encryption using this flag, you will make the compression
 >ration slightly lower (for all sane files). If, however, you run gzip
 >without "rsyncable", or compress in any other way, you will totally
 >destroy the rsync friendliness of the system. In such a case, you are
 >much better off just encrypting with gpg.

So am I right in thinking that 'sane' files encryted using the --rsyncable
flag will do well - but not as well as those where rsyncrypto controls the
compression becuase it is able to align the block boundaries - or is it that
the file will be double compressed? Or something else?

 > Finally is an encrypted
 >file larger than the original?
 >
> The encryption adds some overhead, yes. Expect an increase in the order
> of magnitude of 100 bytes per file + ~8 bytes per 12KB over the
> compressed size of the original file. I don"t think this is anything you
> should be worried about.
Yes - pretty insignificant - thanks.

Thanks

Barry (uktekky)