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Re: [openpgp] Intended Recipient Fingerprint signature subpacket

2019-03-19 05:27:40
Vincent Breitmoser <look@my.amazin.horse> writes:

No feedback on this at all?  Should I maybe create a website and logo for
a surreptitious forwarding attack?

I agree that it is a useful feature.  It is implemented as proposed in
Sequoia, you can designate recipients while encrypting a message, and
during signature verification it constrains the validity of the
signatures.

I'll add some more motivation: There is currently no way to distinguish
signatures made for plaintext messages from signatures made for encrypted
messages.

This opens up a scenario where a message is sent as signed cleartext (which 
many
people do by default), and only encrypted at a later point, for example by an
inbound message encryption feature. At that point, there is no way for a mail
client to tell whether this was actually an e2e encrypted message, or sent in
the clear.

As a straightforward fix, I propose an additional "sent in the clear" 
subpacket
that indicates when a signature was made over a message that is sent in the
clear, and wasn't intended to authenticate an encrypted message.

I support this proposal.


Thanks,
Justus

Attachment: signature.asc
Description: PGP signature

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