Cryptocurrencies are a type of digital currencies that are relying on cryptographic proofs for confirmation of transactions. Cryptocurrencies usually achieve a unique combination of three features: ensuring limited anonymity, independence from central authority and double spending attack protection. No other group of currencies, including fiat currencies, has this combination of features. We wi...

Analysis of the currency networks is not easy as the transactions are not centralized but rather take place over a large number of banks and commercial entities. Digital crypto currencies, however, require a public ledger to work and provide an opportunity for analysis of currency transactions. A crypto currency is a medium of exchange using cryptography to secure the transactions and to contro...

With the rise of Bitcoin and other virtual currencies, it has become crucial for government regulatory bodies to catch up. Black market sites like the now-defunct Silk Road have continued to exploit the anonymity of Bitcoin to engage in illegal transactions. In order to identify criminal Bitcoin users, the government must respond with an updated criminal subpoena standard that addresses virtual...

Digital currencies, virtual currencies, in-game currencies, etc., have gathered a lot of attention, despite the difficulties of definition, from all corners of society for many years. Cryptocurrency has gained unprecedented attention since the birth of Bitcoin in 2009. Bitcoin is an online system of making and receiving payments in bitcoins. The system distinguishes itself by providing an opens...

Bitcoin is gaining increasing popularity nowadays, even though the crypto-currencies field has plenty of digital currencies that have emerged before the adoption of Bitcoin idea. Bitcoin is a decentralized digital currency which relies on set of miners to maintain a distributed public ledger and peer-to-peer network to broadcast transactions. In this paper, we analyse how transaction validation...

The internet era has generated a requirement for low cost, anonymous and rapidly verifiable transactions to be used for online barter, and fast settling money have emerged as a consequence. For the most part, e-money has fulfilled this role, but the last few years have seen two new types of money emerge. Centralised virtual currencies, usually for the purpose of transacting in social and gaming...

A growing concern emerges regarding the possibility of counterfeiting currencies using digital imaging technologies. In order to help developing resistance against this new type of fraud, this paper presents possible attacking scenarios against supposedly sophisticated document protection systems based on digital watermarking. These new attacks, which would allow even an average counterfeiter t...

Digital payment systems are an evolving field in present day with the recent enhancements in seamless digital currencies. Thus, despite the benefits of cryptocurrency based digital payments systems, their adoption and diffusion within general payment platform domain are significantly hindered. The blockchain architecture is widely recognized as a promising mechanism to support the management of...