State Actors

https://www.rand.org/content/dam/rand/pubs/testimonies/CT400/CT490/RAND_CT490.pdf

Receive direction, funding, or technical assistance from nation-states; highly sophisticated and often use the most-sophisticated methods (e.g., zero-day vulnerabilities); targeted and persistent

https://katzenpost.network/slides/2017-12-modern-mixnets.pdf

https://www.youtube.com/watch?v=7zIWrNqiTLI

CISA

https://www.cisa.gov/topics/cyber-threats-and-advisories/advanced-persistent-threats/russia

https://www.graphus.ai/blog/10-nation-state-cyberattack-facts-you-need-to-know/

https://forum.zcashcommunity.com/t/the-nym-mixnet-for-network-privacy-for-zcash/46324

ISPs can easily snoop on network traffic to passively record Zcash activity, and adversaries such as Chainalysis have the ability to do both passive surveillance of the large portion of p2p traffic in a network (as it was revealed it had done to the much larger Bitcoin p2p network) and active attacks. The importance of network-level privacy is explicitly called out even in the original Zerocash paper (Section 6.4).

Traffic Analysis by Adversaries with Partial Visibility, 2023

An ISP is one example of an adversary that can see inter-entity connections and use this data for traffic analysis.