Re: On email and web security

[George Michaelson <[e-mail]>]

I thought bloom filters + cryptography == group crypto.

(not a cryptographer, deep trawling memory of articles read many years ago)

On Thu, Jan 14, 2016 at 4:23 PM, Phillip Hallam-Baker <[e-mail]
> wrote:

> On Wed, Jan 13, 2016 at 9:43 PM, John Levine <[e-mail]> wrote:
> >>Well the question I responded to was wondering if there was a way to
> >>have the list software re-encrypt to the members without being able to
> >>decrypt the message first. If I understand correctly, you're saying that
> >>S/MIME can't do that either?
> >
> > Not unless there is something hidden inside all of the X.509 glop that
> > I'm unaware of.  Message bodies are encrypted with a session key
> > which is in turn encrypted with the public keys of the message
> > recipients.  Nothing magic there.
>
> You end up having to modify the clients that decrypt the messages.
>
> The sender merely needs to use an encryption scheme that is based on
> an algorithm that there is a recryption scheme for. I have only seen
> Diffie Hellman based schemes. But since the receiver code is likely to
> be for the new CFRG ECDH algorithms, you are backed up on the sender
> and receiver side.
>
> There are probably ways you could shoehorn this into S/MIME and
> OpenPGP but why not do the job right and extend wherever necessary?
> the client code has to change anyway.
>
>