Re: Encryption question

[Hollis Johnson <hollis () cisco com>]

Lars. That's interesting. I always thought Priv/Pub keys had to be composed 
of two primes. If you "combine" them (i'm thinking p*q) the result is no 
longer prime -- although it may not be any easier to break -- Is that what 
you meant? or did you mean applying one then the other??

Thanks for any additional info :-)

Hollis

At 07:17 PM 2/25/2004 +0100, Lars Georg Paulsen wrote:
> The encrypted key you have made, is not valid. Bob can't decrypt the
> messange with his public nor with is private.
>
> If alice sends a message to bob, and what him to be the only one to read
> it, she will encrypt it with his public key. And to make sure bob can
> trust the message, and tell for sure it's from alice, she will sign the
> message with alice private key.
>
> What you think of, combinding a private key and a public to make a new
> key, is the himlich method. The way describe above takes quite long time
> to decrypt.
>
> Another scenarior, is to make to new keys that are identical.
> This you do by combinding private keys and public keys.
> Alice makes a new key with her private and bobs public key.
> Bobs makes a new key with his private and alices public key.
> The two new keys are now identical, can not be produced by any
> outsiders.
>
> Hopes this answer a bit of your question.
>
> regards
> Lars Georg Paulsen.
>
> On Tue, 2004-02-24 at 20:01, Preston, Tony wrote:
> > Tony Preston
> > Systems Engineer, AS&T Inc.
> > Division of L3 Corporation
> > (609) 485-0205 x 181
> >
> > I have what is a rather basic question...  I probably am missing something
> > so I thought I would ask here.
> >
> > Alice and Bob both have a public and private key.
> >
> > Alice encrypts her email to Bob using his public key.  Sends the email and
> > Bob decrypts it using his keys..
> >
> > Since both Bob and Alice's public keys are known, Why can't I take Alice's
> > public key and create a key pair using any other private key.  Now, I fake
> > an electronic signature from Alice using the pair I created and send a 
> bogus
> > encrypted message to Bob with my "fake" Alice signature.  Bob checks the
> > signature by using the public key and it is valid.   Bob assumes the 
> message
> > is from Alice...
> >
> > What prevents me from spoofing someone's electronic signature this way?
> >
> >
> >
> > ---------------------------------------------------------------------------
> > 
> ----------------------------------------------------------------------------
> >
> >
> >
>
>
> ---------------------------------------------------------------------------
> ----------------------------------------------------------------------------


---------------------------------------------------------------------------
----------------------------------------------------------------------------