Retrieving a session key

Bruno Wolff III bruno at
Fri Nov 12 15:38:31 CET 1999

On Fri, Nov 12, 1999 at 09:37:20PM +0100,
  Werner Koch <wk at> wrote:
> Bruno Wolff III <bruno at> writes:
> > Are they any plans to add features to easily allow someone to retreive a
> > session key from an encrypted message and allow someone to retrieve an
> > encrypted message with that session key?
> > 
> > This would make it easier to comply with court orders to decrypt messages
> > without turning over your private key, which would compromise all messages
> > using that key.
> And that is good reason for me not to do so.  It is easy to modify
> GnuPG in this way and some person can do this on order of a court. 
> However, you need the private key anyway to decrypt the session key,
> so why should this make sense at all.  The only way it might be usable
> is to store every session key ever used in a somehow protected DB - I
> call this key recovery ...

Say a court orders me to decrypt a message. I can do that or go to jail
for contempt and I decide that I would prefer to decrypt the message.
I need to decrypt it in some way that they believe the message I have given
them is correct. Currently the only easy way to do this is by giving them
my passphrase and private key. However this allows them to decrypt other
messages, that they don't have court orders for.

If I had the option of easily retrieving the session key I can avoid that.
The procedure would be that, they would give me a copy of the message.
I would run gnupg while not under surveillance and have it tell me what
the session key is. I would have to supply the passphrase, but it wouldn't
have to be provided to the court. Then I go back to the court with the
session key and they run gnupg and it decrypts the message for them, so that
they know they have the real plain text message.

This can all be done now by hand, but it will be a pain in the rear to
do. Being able to do this easily may make the difference in being ordered
to produce a session key instead of being ordered to produce a private key
and passphrase.

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