Digital currencies like Bitcoin rely on cryptographic primitives to operate. However, past experience shows that cryptographic primitives do not last forever: increased computational power and advanced cryptanalysis cause primitives to break frequently, and motivate the development of new ones. It is therefore crucial for maintaining trust in a crypto currency to anticipate such breakage. We pr...

The Bitcoin has emerged as a fascinating phenomenon in the Financial markets. Without any central authority issuing the currency, the Bitcoin has been associated with controversy ever since its popularity, accompanied by increased public interest, reached high levels. Here, we contribute to the discussion by examining the potential drivers of Bitcoin prices, ranging from fundamental sources to ...

In recent years, there has been a lot of hype and interest around Bitcoin and cryptocurrencies. Following the invention of Bitcoin in 2008, blockchain, the public ledger that supports Bitcoin transaction, has also emerged as a hot topic. Blockchain has attracted attention from many parties around the world including academic scholars, practitioners in many industries, and policymakers in many T...

At the current stratospheric value of Bitcoin, miners with access to significant computational horsepower are literally printing money. For example, the first operator of a USD $1,500 custom ASIC mining platform claims to have recouped his investment in less than three weeks in early February 2013, and the value of a bitcoin has more than tripled since then. Not surprisingly, cybercriminals hav...

The Bitcoin whitepaper [1] states that security of the system is guaranteed as long as honest miners control more than half of the current total computational power. The whitepaper assumes a static difficulty, thus it is equally hard to solve a cryptographic proof-of-work puzzle for any given moment of the system history. However, the real Bitcoin network is using an adaptive difficulty adjustm...

In this work, we present our early stage results on a Conflicts Check Protocol (CCP) that enables preventing potential attacks on bitcoin system. Based on the observation and discovery of a common symptom that many attacks may generate, CCP refines the current bitcoin systems by proposing a novel arbitration mechanism that is capable to determine the approval or abandon of certain transactions ...

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...

We propose Mixcoin, a protocol to facilitate anonymous payments using the Bitcoin currency system. We build on the emergent phenomenon of currency mixes, adding an accountability mechanism to expose theft by mixes. Unlike other proposals to improve anonymity with Bitcoin our scheme can be deployed immediately with no changes to Bitcoin itself. We demonstrate that economic incentives of mixes an...

We examine a protocol πbeacon that outputs unpredictable and publicly verifiable randomness, meaning that the output is unknown at the time that πbeacon starts, yet everyone can verify that the output is close to uniform after πbeacon terminates. We show that πbeacon can be instantiated via Bitcoin under sensible assumptions; in particular we consider an adversary with an arbitrarily large init...

The Bitcoin has emerged as a fascinating phenomenon in the financial markets. Without any central authority issuing the currency, the Bitcoin has been associated with controversy ever since its popularity, accompanied by increased public interest, reached high levels. Here, we contribute to the discussion by examining the potential drivers of Bitcoin prices, ranging from fundamental sources to ...