Alex Biryukov, Ivan Pustogarov, "Proof-of-Work as Anonymous Micropayment: Rewarding a Tor Relay", Financial Cryptography 2015, Puerto-Rico, USA. ( paper)

Alex Biryukov, Ivan Pustogarov, "Bitcoin over Tor isn't a good idea", IEEE Security and Privacy Symposium 2015, ( paper, slides)



See also our work on memory-hard proofs of work, like Argon2.