Biblio

We present TendrilStaller, an eclipse attack targeting at Bitcoin's peer-to-peer network. TendrilStaller enables an adversary to delay block propagation to a victim for 10 minutes. The adversary thus impedes the victim from getting the latest blockchain state. It only takes as few as one Bitcoin full node and two light weight nodes to perform the attack. The light weight nodes perform a subset of the functions of a full Bitcoin node. The attack exploits a recent block propagation protocol introduced in April 2016. The protocol prescribes a Bitcoin node to select 3 neighbors that can send new blocks unsolicited. These neighbors are selected based on their recent performance in providing blocks quickly. The adversary induces the victim to select 3 attack nodes by having attack nodes send valid blocks to the victim more quickly than other neighbors. For this purpose, the adversary deploys a handful of light weight nodes so that the adversary itself receives new blocks faster. The adversary then performs the attack to delay blocks propagated to the victim. We implement the attack on top of current default Bitcoin protocol We deploy the attack nodes in multiple locations around the globe and randomly select victim nodes. Depending on the round-trip time between the adversary and the victim, 50%-85% of the blocks could be delayed to the victim. We further show that the adoption of light weight nodes greatly increases the attack probability by 15% in average. Finally, we propose several countermeasures to mitigate this eclipse attack.

Bitcoin provides freshness properties by forming a blockchain where each block is associated with its timestamp and the previous block. Due to these properties, the Bitcoin protocol is being used as a decentralized, trusted, and secure timestamping service. Although Bitcoin participants which create new blocks cannot modify their order, they can manipulate timestamps almost undetected. This undermines the Bitcoin protocol as a reliable timestamping service. In particular, a newcomer that synchronizes the entire blockchain has a little guarantee about timestamps of all blocks. In this paper, we present a simple yet powerful mechanism that increases the reliability of Bitcoin timestamps. Our protocol can provide evidence that a block was created within a certain time range. The protocol is efficient, backward compatible, and surprisingly, currently deployed SSL/TLS servers can act as reference time sources. The protocol has many applications and can be used for detecting various attacks against the Bitcoin protocol.

Bitcoin is a decentralized digital currency, widely used for its perceived anonymity property, and has surged in popularity in recent years. Bitcoin publishes the complete transaction history in a public ledger, under pseudonyms of users. This is an alternative way to prevent double-spending attack instead of central authority. Therefore, if pseudonyms of users are attached to their identities in real world, the anonymity of Bitcoin will be a serious vulnerability. It is necessary to enhance anonymity of Bitcoin by a coin mixing service or other modifications in Bitcoin protocol. But in a coin mixing service, the relationship among input and output addresses is not hidden from the mixing service provider. So the mixing server still has the ability to track the transaction records of Bitcoin users. To solve this problem, We present a new coin mixing scheme to ensure that the relationship between input and output addresses of any users is invisible for the mixing server. We make use of a ring signature algorithm to ensure that the mixing server can't distinguish specific transaction from all these addresses. The ring signature ensures that a signature is signed by one of its users in the ring and doesn't leak any information about who signed it. Furthermore, the scheme is fully compatible with existing Bitcoin protocol and easily to scale for large amount of users.

When Bitcoin was first introduced to the world in 2008 by an enigmatic programmer going by the pseudonym Satoshi Nakamoto, it was billed as the world's first decentralized virtual currency. Offering the first credible incarnation of a digital currency, Bitcoin was based on the principal of peer to peer transactions involving a complex public address and a private key that only the owner of the coin would know. This paper will seek to investigate how the usage and value of Bitcoin is affected by current events in the cyber environment. Is an advancement in the digital security of Bitcoin reflected by the value of the currency and conversely does a major security breech have a negative effect? By analyzing statistical data of the market value of Bitcoin at specific points where the currency has fluctuated dramatically, it is believed that trends can be found. This paper proposes that based on the data analyzed, the current integrity of the Bitcoin security is trusted by general users and the value and usage of the currency is growing. All the major fluctuations of the currency can be linked to significant events within the digital security environment however these fluctuations are beginning to decrease in frequency and severity. Bitcoin is still a volatile currency but this paper concludes that this is a result of security flaws in Bitcoin services as opposed to the Bitcoin protocol itself.