Anonymous filter subscription: This feature guarantees that nodes can anonymously subscribe for a message filter (i.e., without revealing their exact content filter). As such, no adversary in the WakuFilter protocol would be able to link nodes to their subscribed content filers. The current version of the WakuFilter protocol does not provide anonymity as the subscribing node has a direct connection to the full node and explicitly submits its content filter to be notified about the matching messages. However, one can consider preserving anonymity through one of the following ways:
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By hiding the source of the subscription i.e., anonymous communication. That is the subscribing node shall hide all its PII in its filter request e.g., its IP address. This can happen by the utilization of a proxy server or by using Tor.
+Note that the current structure of filter requests i.e., FilterRPC does not embody any piece of PII, otherwise, such data fields must be treated carefully to achieve anonymity.
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By deploying secure 2-party computations in which the subscribing node obtains the messages matching a content filter whereas the full node learns nothing about the content filter as well as the messages pushed to the subscribing node. Examples of such 2PC protocols are Oblivious Transfers and one-way Private Set Intersections (PSI).
Fix: Ensure contentFilter is a repeated field, on implementation
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Change: Add ability to unsubscribe from filters. Make subscribe an explicit boolean indication. Edit protobuf field order to be consistent with libp2p.