Using symmettric keys in GPG

[Atom 'Smasher']

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On Wed, 9 Jun 2004, Varun Pitale wrote:

> I want to use GPG in our office, and want to use symmetric encryption for
> sending files.. The reason being the files are too big (> 400 MB) and to
> encrypt them using public-key becomes too slow.. How can I generate
> symmetric keys using my choice of the algorithm and will the receiver
> automatically find out what algorithm I am using or does he have to make
> changes to his GPG too?/
==============================

only the session key is encrypted asymmetrically, the bulk data (aka the
message) encryption is done symmetrically in pgp/gpg (ok, there are a few
bits aside from the session key that are encrypted asymmetrically, but
it's still going to be a tiny bit of data that's handled that way).

since the asymmetrically encrypted part is small, you won't notice any
difference in speed between using gpg in the "normal" public/private key
way vs symmetric encryption (except for the compression, which can run
slow).

in real life tests, it might ~seem~ like it's taking longer using
asymmetric crypto, but that's probably because of the compression (which
is usually on by default for asymmetric encryption)... if you set
'--compress-algo 0' (which turns off compression) then symmetric and
asymmetric encryption will both take about the same time.

if you *really* want to use symmetric crypto, let us know... one of us can
post details....


	...atom

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