In article <CABkgnnVmJf66ZJLToFm9_o34P3FswezVRFguuFrgMJeQv_TMgg@xxxxxxxxxxxxxx> you write: >On 21 April 2017 at 12:11, John Levine <johnl@xxxxxxxxx> wrote: >> >> If a recipient is cooperative, and sends you back a message signed >> with the same key to which you encrypted the message, that tells you >> he got it, but that's not a very interesting case. > >It's also abuse of the cryptographic primitives, I hope that this >isn't really how it works and you are eliding certain key details. It doesn't use the same session key, it uses the same public key. It's not obvious to me why that would be wrong. R's, John