lox-troll-patrol-extension

Lox: A privacy preserving bridge distribution system

Lox is a privacy preserving, reputation-based bridge distribution system that is being integrated into Tor. This integration has multiple pieces that are divided into crates within this workspace.

Current status

lox-library

The protocols in the Lox-library are consistent with the Lox system described in Tulloch and Goldberg (and in greater detail here).

Some changes have been made to integrate the existing Lox protocols with Tor's bridge distributor rdsys, but so far, these have not affected the Lox protocols themselves.

These changes are necessary to keep the consistentcy of bridges in buckets that Lox requires while working with the reality of h how rdsys/Tor currently receives and distributes information about bridges. The changes to Lox are:

1. Add a uid_fingerprint field to the BridgeLine which helps with bridge lookup and corresponds (roughly) to the unique fingerprint rdsys gives to each bridge (made up of a hash of the IP and pluggable transport type)
2. Allow for the details of a bridge to be updated. This has been added to crates/lox-library/src/lib.rs and accounts for the fact that some details of an existing bridge (i.e., that has a matching fingerprint) may be updated from time to time.
3. Allow for a bridge to be replaced. This has also been added to crates/lox-library/src/lib.rs and accounts for the fact that Tor currently does not have a robust way of knowing that a bridge is blocked, but does have some tests (namely, bridgestrap and onbasca) to know if a bridge should not be distributed. Since we do not know if the results of these tests indicate a blocking event, we are allowing for bridges that rdsys marks as gone to be updated without penalty in the Lox library.
4. The vectors within bridge_table.rs have been refactored into HashMaps that use a unique u32 for lookup. This will be backed by some kind of persistent storage prior to deployment.

lox-distributor

The lox-distributor acts as an intermediary between rdsys, the lox-library's server protocols and client requests from lox-wasm integrated into Tor browser.

Currently, it receives resources from rdsys through the rdsys-backend-api, parses them into new, changed, or gone resources (i.e., BridgeLines) that can then be added, updated or replaced in the Lox bridge_table.

The lox-distributor also handles client requests from the Tor browser for Lox credentials and all related functionality.

lox-wasm

The lox-wasm library implements the client side of the lox-library with wasm-bindgen to facilitate it's integration into Tor browser.

lox-utils

lox-utils is a set of functions that don't really belong to one specific lox project but are useful across several projects within this Lox workspace.

rdsys-backend-api

The rdsys-backend-api polls rdsys and translates resources received from rdsys into the proper format expected by the lox-distributor. Next up for the rdsys-backend-api:

Since Lox requires bridge persistence more than other bridge distributors the rdsys-backend-api requires additional logic to determine which gone resources should be handed out to the lox-distributor. This likely means: gone resources that have been failing tests, and are thus gone for x length of time, since we will not want a resource that is down temporarily to be completely removed from whatever bucket it has been placed in.

Building the various parts of Lox

Roadmap

Please see our plans for this workspace in the wiki.