ietf-openpgp
[Top] [All Lists]

Re: Algorithms and specifiers

1998-03-21 15:11:58
One case to consider is where there are multiple recipients.  PGP 5.X
tries to select an encryption algorithm which is acceptable to all.
If there is more than one acceptable one, it chooses the algorithm with
the earliest average position in each recipient's preference list.

However it may be that there are no algorithms which are both acceptable
to all recipients and acceptable to (or even implemented by) the sender.
This can actually happen pretty easily since the code assumes that
unpreferenced RSA keys are from PGP 2.X users who can only accept IDEA.

In 5.0, we aborted with an error in that case, and the user was informed
that he could not encrypt to those recipients.  However Phil Zimmermann
did not like that failure mode, so in 5.5 we changed it so that in that
case we go ahead and encrypt anyway, even though not all recipients may
be able to read the message.

Hal

<Prev in Thread] Current Thread [Next in Thread>