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author | Nick Mathewson <nickm@torproject.org> | 2023-10-12 12:27:58 -0400 |
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committer | Nick Mathewson <nickm@torproject.org> | 2023-10-12 12:27:58 -0400 |
commit | f7e5a95ee96d8ef52c1732d066c1249a6f84391e (patch) | |
tree | 2e1ddd85f471143518d0df7c7645d066d43bc149 /spec/padding-spec/overview.md | |
parent | e4e0d93d56ee8c1aec4c2efaa7046b651f0fe55c (diff) | |
download | torspec-f7e5a95ee96d8ef52c1732d066c1249a6f84391e.tar.gz torspec-f7e5a95ee96d8ef52c1732d066c1249a6f84391e.zip |
Convert text specifications to mdbook.
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-rw-r--r-- | spec/padding-spec/overview.md | 28 |
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diff --git a/spec/padding-spec/overview.md b/spec/padding-spec/overview.md new file mode 100644 index 0000000..76c8865 --- /dev/null +++ b/spec/padding-spec/overview.md @@ -0,0 +1,28 @@ +<a id="padding-spec.txt-1"></a> +# Overview + +Tor supports two classes of cover traffic: connection-level padding, and +circuit-level padding. + +Connection-level padding uses the CELL_PADDING cell command for cover +traffic, where as circuit-level padding uses the RELAY_COMMAND_DROP relay +command. CELL_PADDING is single-hop only and can be differentiated from +normal traffic by Tor relays ("internal" observers), but not by entities +monitoring Tor OR connections ("external" observers). + +RELAY_COMMAND_DROP is multi-hop, and is not visible to intermediate Tor +relays, because the relay command field is covered by circuit layer +encryption. Moreover, Tor's 'recognized' field allows RELAY_COMMAND_DROP +padding to be sent to any intermediate node in a circuit (as per Section +6.1 of tor-spec.txt). + +Tor uses both connection level and circuit level padding. Connection +level padding is described in section 2. Circuit level padding is +described in section 3. + +The circuit-level padding system is completely orthogonal to the +connection-level padding. The connection-level padding system regards +circuit-level padding as normal data traffic, and hence the connection-level +padding system will not add any additional overhead while the circuit-level +padding system is actively padding. + |