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Re: Where does your data want to go today?
On 30 May 1996 07:56:26 pdt, [email protected] wrote:
>From: IN%"[email protected]" "Marshall Clow" 29-MAY-1996 19:18:31.60
>
>>* Why encrypt before compression? If the encryption is any good, then the
>>encrypted data won't compress much at all. However, compression before
>>encryption has its own problems.
>
> What problems does compression before encryption have? It at least
>seems to work for PGP.
The most significant would be the presence of a compression header (what
has the data
telling how to decompress a datastream). If you leave this in (for
instance, assuming you
were to use PKZIP (STUPID!) you would have PK as the first two bytes
EVERY TIME!) you give
your codebreaker a HUGE advantage. You can bypass this by removing ANY
information which
isn't message specific and standardizing on one compression method.
Alternately, you could
use your session key to encrypt a length word and then pad the start (and
end) with a
string of random characters.
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