Fwd: crypto flaw in secure mail standards

Anthony E. Greene agreene@pobox.com
Mon Jun 25 08:11:01 2001

On Mon, 25 Jun 2001, Don Davis wrote:

>>On Sun, 24 Jun 2001, David Shaw wrote:
>>> It is thus possible for Alice to send a signed and encrypted mail to
>>> Bob, Bob decrypts it, recovering the clearsigned message, and then
>>> re-encrypts it to Charlie. Charlie will receive the original document
>>> with Alice's signature intact.
>Anthony Greene replied:
>> The encryption in this example is beside the point and in fact is a
>> distraction to the primary argument; that signed data can be taken out o=
>> context, given sufficiently vague data and a forgeable delivery mechanis=
>for na=EFve users (my paper's focus), encryption is pivotal:
>their ignorance of PKI subtleties misleads them into
>thinking that forwarding a signed-&-encrypted message
>is impossible, when of course with secure-mail crypto,
>forwarding is straightforward. with a signed plaintext
>delivery, Charlie might more readily see and understand
>that Alice's signed message doesn't refer to him.
>=09=09=09=09=09- don davis, boston
I see, but as has been pointed out, that problem exists with paper, and is not really a software problem. Tony --=20 Anthony E. Greene <agreene@pobox.com> <http://www.pobox.com/~agreene/> PGP Key: 0x6C94239D/7B3D BD7D 7D91 1B44 BA26 C484 A42A 60DD 6C94 239D Chat: AOL/Yahoo: TonyG05 MSN: te_greene Linux. The choice of a GNU Generation. <http://www.linux.org/>