Motivated by the great success and adoption of Bitcoin, a number of cryptocurrencies such as Litecoin, Dogecoin, and Ethereum are becoming increasingly popular. Although existing blockchainbased cryptocurrency schemes can ensure reasonable security for transactions, they do not consider any notion of fairness. Fair exchange allows two players to exchange digital “items”, such as digital signatu...

The major advantages of blockchain based cryptocurrencies are the independent verifiability of transactions and the anonymity that they allow. Blockchains can also process transactions at much lower cost than banks and credit card companies. On the other hand, the value of cryptocurrencies is quite volatile. In addition, the crypto-ecosystem is not easy to access for many less technologically s...

To the knowledge of the author, this is the first time it has been shown that interest rates that are extremely high by modern standards are necessary within a zero-sum monetary system. Extreme interest rates persisted for long periods of time in many places. Prior to the invention of banking, most money was hard-money in the form of some type of coin. Here a model is presented that examines th...

Bitcoin cryptocurrency demonstrated the utility of global consensus across thousands of nodes, changing the world of digital transactions forever. In the early days of Bitcoin, the performance of its probabilistic proof-of-work (PoW) based consensus fabric, also known as blockchain, was not a major issue. Bitcoin became a success story, despite its consensus latencies on the order of an hour an...

Suppose that N players share cryptocurrency using an M out-of-N multisig scheme. If N−M+1 players disappear, the remaining ones have a problem: They’ve permanently lost their funds. We introduce Paralysis Proofs. A Paralysis Proof is a proof that players cannot act in concert, e.g., some players have become unavailable. Paralysis Proofs can support the construction of a Paralysis Proof System, ...

The cryptocurrency market surpassed the barrier of $100 billion market capitalization in June 2017, after months of steady growth. Despite its increasing relevance in the financial world, a comprehensive analysis of the whole system is still lacking, as most studies have focused exclusively on the behaviour of one (Bitcoin) or few cryptocurrencies. Here, we consider the history of the entire ma...

We improve the design and implementation of two-party and three-party authenticated dynamic dictionaries and apply these dictionaries to cryptocurrency ledgers. A public ledger (blockchain) in a cryptocurrency needs to be easily verifiable. However, maintaining a data structure of all account balances, in order to verify whether a transaction is valid, can be quite burdensome: a verifier who do...

In this paper we discuss Bitcoin, the leader among the existing cryptocurrencies, to analyse its trends, success factors, current challenges and probable solutions to make it even better. In the introduction section, we discuss the history and working mechanism of Bitcoin. In the background section, we develop the ideas that evolved in the process of making a stable cryptocurrency. We also anal...

This article introduces a method of hiding transaction amounts in the strongly decentralized anonymous cryptocurrency Monero. Similar to Bitcoin, Monero is cryptocurrency which is distributed through a proof of work “mining” process. The original Monero protocol was based on CryptoNote, which uses Ring Signatures and one-time keys to hide the destination and origin of transactions. Recently the...