Show that an encrypted message was signed, without decrypting it

[Stefan Claas]

Hi Werner and all,

I was reading old GnuPG threads were people were asking if it's possible
to extract a signature from an encrypted message.

I would like to ask, I don't know if this is already possible or if it's planned,
if Alice would request from Bob that he always signs his messages and Bob, lazy
as he is, often forgets this, can Alice check if Bob's encrypted message(s) have
signed byte(s) set, without actually decrypting or revealing Bob's identity? If
the encrypted messages would not be signed then Alice can simply discard the
message(s). And is this optional in GnuPG, in case it is already implemented?

Regards
Stefan

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