[tor-bugs] #22948 [Core Tor/Tor]: Padding and Keepalive cells should have random payloads

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#22948: Padding and Keepalive cells should have random payloads
------------------------------+--------------------------------------
     Reporter:  teor          |      Owner:
         Type:  defect        |     Status:  new
     Priority:  Medium        |  Milestone:  Tor: 0.3.1.x-final
    Component:  Core Tor/Tor  |    Version:  Tor: 0.3.1.1-alpha
     Severity:  Normal        |   Keywords:  tor-spec, security-maybe
Actual Points:                |  Parent ID:  #18856
       Points:  0.5           |   Reviewer:
      Sponsor:                |
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 tor-spec says:
 {{{
    Link padding can be created by sending PADDING or VPADDING cells
    along the connection; relay cells of type "DROP" can be used for
    long-range padding.  The contents of a PADDING, VPADDING, or DROP
    cell SHOULD be chosen randomly, and MUST be ignored.
 }}}
 https://gitweb.torproject.org/torspec.git/tree/tor-spec.txt#n1534

 But padding cells sent by channelpadding_send_padding_cell_for_callback()
 and keepalive cells sent by run_connection_housekeeping() have a payload
 of all zero bytes.

 I don't know if this is a security issue or not. It is probably ok, unless
 Tor has compression enabled on its TLS connections. If compression is
 enabled, all the padding data size calculations will be wrong.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/22948>
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