Proof-of-work (PoW) is an algorithmic tool used to secure networks by imposing a
computational cost on participating devices. Unfortunately, traditional PoW schemes require …

Unwanted traffic remains a fundamental problem for networked systems. Proof-of-work
(PoW) is a defense mechanism that adds a client-specific challenge at the start of a …

The open nature of Internet services has been of great value to users, enabling dramatic
innovation and evolution of services. However, this openness permits many abuses of open …

Cuckoo Cycle: a memory-hard proof-of-work system Page 1 Cuckoo Cycle: a memory-hard
proof-of-work system John Tromp February 1, 2014 Abstract We introduce the first trivially …

A decision task is a distributed input-output problem in which each process starts with its
input value and eventually produces its output value. Examples of such decision tasks are …

We formalize the notion of a proof of work (POW). In many cryptographic protocols, a prover
seeks to convince a verifier that she possesses knowledge of a secret or that a certain …

We introduce the concept of memory-hard proof-of-work algorithms and argue that in order
for proof-of-work based systems to be secure against attacks using custom hardware, they …

We initiate a study of security in asynchronous networks. We consider a completely
asynchronous network where every two parties are connected via a private channel, and …

Zero knowledge proofs are one of the most influential concepts in theoretical computer
science. In the seminal definition due to Goldwasser, Micali and Rackoff dating back to the …

Motivated by the recent success of Bitcoin we study the question of constructing distributed
cryptographic protocols in a fully peer-to-peer scenario under the assumption that the …