Re: [tor-bugs] #4744 [Tor Bridge]: GFW probes based on Tor's SSL cipher list

["Tor Bug Tracker & Wiki" <torproject-admin@xxxxxxxxxxxxxx>]

#4744: GFW probes based on Tor's SSL cipher list
--------------------------------+-------------------------------------------
 Reporter:  asn                 |          Owner:  nickm             
     Type:  defect              |         Status:  needs_review      
 Priority:  major               |      Milestone:  Tor: 0.2.3.x-final
Component:  Tor Bridge          |        Version:                    
 Keywords:  tls fingerprinting  |         Parent:  #4185             
   Points:                      |   Actualpoints:                    
--------------------------------+-------------------------------------------

Comment(by asn):

 On the server side, if the client's ciphersuites indicate 198-awareness,
 maybe passing
 `EDH+AES:EDH+3DES:!LOW:!MEDIUM:!NULL:!EDH-RSA-DES-CBC3-SHA`
 to `SSL_set_cipher_list()` will do the filtering specified by proposal
 198?

 {{{
   Otherwise, the ClientHello has these semantics: The inclusion of any
   cipher supported by OpenSSL 1.0.0 means that the client supports it,
   with the exception of
       SSL_RSA_FIPS_WITH_3DES_EDE_CBC_SHA
   which is never supported. Clients MUST advertise support for at least
 one of
   TLS_DHE_RSA_WITH_AES_256_CBC_SHA or TLS_DHE_RSA_WITH_AES_128_CBC_SHA.

   The server MUST choose a ciphersuite with ephemeral keys for forward
   secrecy; MUST NOT choose a weak or null ciphersuite; and SHOULD NOT
   choose any cipher other than AES or 3DES.
 }}}

-- 
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/4744#comment:28>
Tor Bug Tracker & Wiki <https://trac.torproject.org/>
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