multiple message destinations

From: tribble@xanadu.com (E. Dean Tribble)
Date: Fri, 23 Oct 92 14:41:59 PDT
To: cypherpunks@toad.com
Subject: multiple message destinations
Message-ID: <9210231806.AA12129@xanadu.xanadu.com>
MIME-Version: 1.0
Content-Type: text/plain
Mail typically wants to get sent to multiple receivers, all with
different private keys. I vaguely recall that the way PGP works is it
generates a symetric cypher key and encrypts the message with that,
then encrypts the generated key with the public key of the intended
receiver. Is that how it works?
Given that, it should be straightforward (and maybe it already does)
encrypt the generated key with several public keys so you get one
package that can be unsealed by any of several different receivers.
Are there other ways to handle sending to multiple receivers?
dean

Dean:
>Are there other ways to handle sending to multiple receivers?

1) You can send it to a service which copies the message and resends
it as many times as you need.  Or send it yourself.

2) You can have the multiple recipients each share a key and let them
trust each other.  (Not recommended for the paranoid).

3) You can use a secret sharing system which is tied to a private key,
such that revealing the secret allows for the derivation of the
private key.  The secret itself is a different private key.  (I'm not
up on the details of these schemes.)

Eric

Doies the scheme I suggested (and I'm sure is not original) work?
Using all the various private keys to encrypt a single cypher key that
the rest of the message is encrypted with?

dean

Re: multiple encryptions of a message key.

Yes, it works.  Sorry.

Eric

>From: tribble@xanadu.com (E. Dean Tribble)

>Mail typically wants to get sent to multiple receivers, all with
>different private keys.  I vaguely recall that the way PGP works is it
>generates a symetric cypher key and encrypts the message with that,
>then encrypts the generated key with the public key of the intended
>receiver.   Is that how it works?

>Given that, it should be straightforward (and maybe it already does)
>encrypt the generated key with several public keys so you get one
>package that can be unsealed by any of several different receivers.

Yes, that should work. PGP doesn't do it, but it would be
straightforward to change it so it could.

Perry