[tor-bugs] #13054 [Tor]: [warn] Invalid result from curve25519 handshake: 4

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#13054: [warn] Invalid result from curve25519 handshake: 4
-----------------------+------------------------------------
 Reporter:  arma       |          Owner:
     Type:  defect     |         Status:  new
 Priority:  normal     |      Milestone:  Tor: 0.2.6.x-final
Component:  Tor        |        Version:
 Keywords:  tor-relay  |  Actual Points:
Parent ID:             |         Points:
-----------------------+------------------------------------
 I get this on the moriatoo relay, which is running git master and is also
 hooked up to a bwauth.

 The messages around it are:
 {{{
 Sep 04 03:21:11.000 [warn] Invalid result from curve25519 handshake: 4
 Sep 04 03:21:11.000 [warn] onion_skin_client_handshake failed.
 Sep 04 03:21:11.000 [warn] circuit_finish_handshake failed.
 }}}

 It actually happens not infrequently, so it's not just a one-off thing.

 The code is
 {{{
   if (bad) {
     log_warn(LD_PROTOCOL, "Invalid result from curve25519 handshake: %d",
 bad);
   }
 }}}
 and I think 4 shows up when
 {{{
   bad |= (tor_memneq(s.auth, auth_candidate, DIGEST256_LEN) << 2);
 }}}

 So I guess the first issue is that "4" is really not a helpful error
 message for me.

 The second issue is to wonder what's gone wrong and whether there's a
 deeper bug.

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/13054>
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