Payment Decorrelation through Point Time Locked Contracts (PTLCs)

Another potential surveillance vector for Lightning payments is that payments are associated with a unique and static payment hash. This payment hash is sent from the recipient to the sender, which is shared with nodes on the route to represent the payment. If sybil nodes were surveilling the network, and it would be wise to assume so, they could coordinate and map payments. With enough hostile nodes, a fairly detailed picture of the flow of funds could be painted.

Taproot's introduction of Schnorr signatures paves the way for a smart contract called Point Time Locked Contracts (PTLCs). PTLCs operate similarly to HTLCs by allowing payments to be identified by nodes. Still, PTLCs come with a handy feature of randomizing its identifier with each hop, making it impossible for nodes to correlate the traffic of sending and receiving nodes.