The first edition of this book was published in 2003. Inevitably, certain parts of the book
became outdated quickly. At the same time new developments have continued apace …

An implicit goal of Bitcoin's reward structure is to diffuse network influence over a diverse,
decentralized population of individual participants. Indeed, Bitcoin's security claims rely on …

Abstract We give Proofs of Work (PoWs) whose hardness is based on well-studied worst-
case assumptions from fine-grained complexity theory. This extends the work of (Ball et al …

In the standard definition of a commitment scheme, the sender commits to a message and
immediately sends the commitment to the recipient interested in it. However the sender may …

We present the Balloon password-hashing algorithm. This is the first practical cryptographic
hash function that:(i) has proven memory-hardness properties in the random-oracle …

Blockchain-based replicated ledgers, pioneered in Bitcoin, are effective against double
spending, but inherently attract centralised mining pools and incompressible transaction …

Abstract Denial of Service (DoS) attacks are a growing threat in network services. The
frequency and intensity of DoS attacks are rapidly increasing day by day. The immense …

This paper develops a theory of multi-instance (mi) security and applies it to provide the first
proof-based support for the classical practice of salting in password-based cryptography. Mi …

We show that the second iterate H^ 2 (M)= H (H (M)) of a random oracle H cannot achieve
strong security in the sense of indifferentiability from a random oracle. We do so by proving …

The" blockchain" distributed ledger pioneered by Bitcoin is effective at preventing double-
spending, but inherently attracts (1)" user cartels" and (2) incompressible delays, as a result …