[Cryptography] Is there a good algorithm providing both compression and encryption at the same time?

[Francois BERENGER]

On Wed, May 6, 2015 at 11:06 PM, Lars Luthman <mail at larsluthman.net> wrote:

> On Wed, 2015-05-06 at 10:15 +0200, Francois BERENGER wrote:
> > I was thinking about something along those lines:
> >
> > compression(clear_text) = (compression_dictionary, compressed_text)
> >
> > then, instead of encrypting the whole resulting pair (to save some time),
> > we would send over the wire
> >
> > (symmetric_encrypt(compression_dictionary, secret_key), compressed_text)
> >
> > Of course, I would like that the compressed_text cannot be uncompressed
> > by someone who doesn't have access to the compression dictionary.
>
> Wouldn't such an algorithm suffer from the same problem as using a block
> cipher in ECB mode?


For performance reasons, I think I will use a block cypher in counter mode.
I need an encryption mode that can parallelize.


> That is, an attacker would be able to infer parts of
> the structure of the plaintext by looking at repeated symbols in the
> output (in this case compressed_text).
>
> Assuming that different references in compressed_text to the same word
> in compression_dictionary are recognisable as referring to the same word
> for someone without access to the plaintext compression_dictionary, of
> course. But if you are reasonably sure that they aren't you have
> essentially encrypted compressed_text as well.
>
>
> --ll
>
> _______________________________________________
> The cryptography mailing list
> cryptography at metzdowd.com
> http://www.metzdowd.com/mailman/listinfo/cryptography
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://www.metzdowd.com/pipermail/cryptography/attachments/20150509/89735fca/attachment.html>