O2.2: Deploy improved bridge distribution systems.
O2.2.1.: Deploy the Salmon bridge distribution system. Salmon, originally proposed in a research paper at PETS’16,1 is an innovative new bridge distribution method designed to make it significantly harder for the GFW to learn about and block obfs4 bridges. With Salmon, users are assigned a reputation score that goes down when one of their bridges is blocked, and it goes up if their assigned bridges remain unblocked. If a user's reputation score gets too low, the user gets blocked, and if it gets high enough, the user can invite others to the system. In order to deploy Salmon, we need to build a solution to test the reachability of the bridges it distributes. Knowing whether a bridge is blocked or unblocked is critical to the reputation system. In this Activity, we will run our 'bridgestrap' reachability testing tool on a VPS in China to feed reachability information back to Salmon.
O2.2.2: Deploy next generation bridge distribution system (rdsys). The tool rdsys2 is the replacement of an aging bridge distribution system. rdsys will do something new—use the reachability data collected by the mechanism created in O2.2.1 to make decisions about which bridges to hand to users. This is a critical improvement, as rdsys will have the capacity to hand out bridges that are not blocked in the user’s location. The ability to use reachability data in a feedback loop also means a faster response to blocking. We can eliminate blocked bridges from the pool while cycling in unblocked bridges. In this Activity we will: improve the quality of code and documentation, conduct usability tests, and add comprehensive metrics to rdsys. We need high-quality metrics to learn what works and doesn’t work for users.