diff --git a/i2p2www/spec/proposals/125-obep-to-one-of-many-tunnels.rst b/i2p2www/spec/proposals/125-obep-to-one-of-many-tunnels.rst index ee22ef13f62d5e8d3f297ab8e4910a19d02ae84e..23312cd0369be4a6d41017ea8a6d4e6fec657c22 100644 --- a/i2p2www/spec/proposals/125-obep-to-one-of-many-tunnels.rst +++ b/i2p2www/spec/proposals/125-obep-to-one-of-many-tunnels.rst @@ -64,6 +64,22 @@ flags for [TUNNEL-DELIVERY]_, which we can leverage to implement these features. Security Implications ===================== +This proposal does not change the amount of information leaked about the OBGW's +target Destination or their view of the NetDB: + +- An adversary that controls the OBEP and is scraping LeaseSets from the NetDB + can already determine whether a message is being sent to a particular + Destination, by searching for the [TunnelId]_ / [RouterIdentity]_ pair. At + worst, the presence of multiple Leases in the TMDI might make it faster to + find a match in the adversary's database. + +- An adversary that is operating a malicious Destination can already gain + information about a connecting victim's view of the NetDB, by publishing + LeaseSets containing different inbound tunnels to different floodfills, and + observing which tunnels the OBGW connects through. From their point of view, + the OBEP selecting which tunnel to use is functionally identical to the OBGW + making the selection. + The multicast flag leaks the fact that the OBGW is multicasting to the OBEPs. This creates a performance vs. privacy trade-off that should be considered when implementing higher-level protocols. Being an optional flag, users can make @@ -147,7 +163,7 @@ Compatibility The only peers that need to be understand the new specification are the OBGWs and the OBEPs. We can therefore make this change compatible with the existing -network by making its use conditional on the target I2P version: +network by making its use conditional on the target I2P version [VERSIONS]_: * The OBGWs must select compatible OBEPs when building outbound tunnels, based on the I2P version advertised in their [RouterInfo]_. @@ -176,3 +192,9 @@ References .. [TUNNEL-DELIVERY] {{ ctags_url('TunnelMessageDeliveryInstructions') }} + +.. [TunnelId] + {{ ctags_url('TunnelId') }} + +.. [VERSIONS] + {{ spec_url('i2np') }}#protocol-versions