A Bitcoin Address Multi-Classification Mechanism Based on Bipartite Graph-Based Maximization Consensus

Bitcoin is widely used as the most classic electronic currency for various electronic services such as exchanges,gambling,marketplaces,and also scams such as high-yield investment projects.Identifying the services operated by a Bitcoin address can help determine the risk level of that address and build an alert model accordingly.Feature engineering can also be used to flesh out labeled addresses and to analyze the current state of Bitcoin in a small way.In this paper,we address the problem of identifying multiple classes of Bitcoin services,and for the poor classification of individual addresses that do not have significant features,we propose a Bitcoin address identification scheme based on joint multi-model prediction using the mapping relationship between addresses and entities.The innovation of the method is to(1)Extract as many valuable features as possible when an address is given to facilitate the multi-class service identification task.(2)Unlike the general supervised model approach,this paper proposes a joint prediction scheme for multiple learners based on address-entity mapping relationships.Specifically,after obtaining the overall features,the address classification and entity clustering tasks are performed separately,and the results are subjected to graph-basedmaximization consensus.The final result ismade to baseline the individual address classification results while satisfying the constraint of having similarly behaving entities as far as possible.By testing and evaluating over 26,000 Bitcoin addresses,our feature extraction method captures more useful features.In addition,the combined multi-learner model obtained results that exceeded the baseline classifier reaching an accuracy of 77.4%.

The linkage between Bitcoin and foreign exchanges in developed and emerging markets

This study investigates the connectedness between Bitcoin and fiat currencies in two groups of countries:the developed G7 and the emerging BRICS.The methodology adopts the regular(R)-vine copula and compares it with two benchmark models:the multivariate t copula and the dynamic conditional correlation(DCC)GARCH model.Moreover,this study examines whether the Bitcoin meltdown of 2013,selloff of 2018,COVID-19 pandemic,2021 crash,and the Russia-Ukraine conflict impact the linkage with conventional currencies.The results indicate that for both currency baskets,R-vine beats the benchmark models.Hence,the dependence is better modeled by providing sufficient information on the shock transmission path.Furthermore,the cross-market linkage slightly increases during the Bitcoin crashes,and reaches significant levels during the 2021 and 2022 crises,which may indicate the end of market isolation of the virtual currency.

Whether and when did bitcoin sentiment matter for investors?Before and during the COVID‑19 pandemic

Using a wavelet coherence approach,this study investigates the relationship between Bitcoin return and Bitcoin-specific sentiment from January 1,2016 to June 30,2021,covering the COVID-19 pandemic period.The results reveal that before the pandemic,sentiment positively drove prices,especially for relatively higher frequencies(2–18 weeks).During the pandemic,the relationship was still positive,but interestingly,the lead-lag relationship disappeared.Employing partial wavelet tools,we factor out the number of COVID-19 cases and deaths and the Equity Market Volatility Infectious Disease Tracker index to observe the direct relationship between a change in sentiment and return.Our results robustly reveal that,before the pandemic,sentiment had a positive effect on return.Although positive coherence still existed during the pandemic,the lead-lag relationship disappeared again.Thus,the causal relationship that states that sentiment leads to return can only be integrated into short-term trading strategies(up to six weeks frequency).

Diversification evidence of bitcoin and gold from wavelet analysis

To measure the diversification capability of Bitcoin,this study employs wavelet analysis to investigate the coherence of Bitcoin price with the equity markets of both the emerging and developed economies,considering the COVID-19 pandemic and the recent Russia-Ukraine war.The results based on the data from January 9,2014 to May 31,2022 reveal that compared with gold,Bitcoin consistently provides diversification opportunities with all six representative market indices examined,specifically under the normal market condition.In particular,for short-term horizons,Bitcoin shows favorably low correlation with each index for all years,whereas exception is observed for gold.In addition,diversification between Bitcoin and gold is demonstrated as well,mainly for short-term investments.However,the diversification benefit is conditional for both Bitcoin and gold under the recent pandemic and war crises.The findings remind investors and portfolio managers planning to incorporate Bitcoin into their portfolios as a diversification tool to be aware of the global geopolitical conditions and other uncertainty in considering their investment tools and durations.

An Optimal Algorithm for Secure Transactions in Bitcoin Based on Blockchain

Technological advancement has made a significant contribution to the change of the economy and the advancement of humanity.Because it is changing how economic transactions are carried out,the blockchain is one of the technical developments that has a lot of promise for this progress.The public record of the Bitcoin blockchain provides dispersed users with evidence of transaction owner-ship by publishing all transaction data from block reward transactions to unspent transaction outputs.Attacks on the public ledger,on the other hand,are a result of the fact that all transaction information are exposed.De-anonymization attacks allow users to link transaction entities and acquire user privacy through specified transaction amounts.As a result,in light of the Bitcoin blockchain system’s priv-acy issues,this scheme combines the concept of coin mixing with encrypted trans-action technology to create a truly anonymous blockchain system that preserves the payer identity and transaction amount privacy.The one-way aggregated sig-nature technique of Boneh,Gentry,and Lynn systematically embeds the notion of mixing into the whole block.The homomorphic encryption approach of Boneh,Goh,and Nissim allows miners to check the legality of encrypted transactions.Miners will validate transactions,conceal transactions,and package transactions as entities in the scheme.Finally,this technique was chosen after a comparison of several privacy-preserving blockchain schemes.It not only ensures complete anonymity,but also keeps transaction storage overhead to a minimum.

Cryptocurrency technology revolution:are Bitcoin prices and terrorist attacks related?

As a financial innovation of the information age,cryptocurrency is a complex concept with clear advantages and disadvantages and is worthy of discussion.Exploring from a terrorism perspective,this study uses the time-varying parameter/stochastic volatil-ity vector autoregression model to explore the risk hedging and terrorist financing capabilities of Bitcoin.Empirical results show that both terrorist incidents and brutality may explain Bitcoin price,but their effects are slightly different.Compared to terrorist brutality,terrorist incidents have a weaker impact on Bitcoin price,showing that Bitcoin investors are more concerned about the number of deaths than the frequency of ter-rorist attacks.In turn,the impact of Bitcoin price on terrorist attacks is negligible.Bitcoin is a potential means of financing terrorism,but it does not currently play an important role.Our research findings can help investors analyze and predict Bitcoin prices and help improve the theoretical system of anti-terrorist financing,helping to maintain world peace and security.

Bitcoin:a new proof‑of‑work system with reduced variance

Since its inception,bitcoin has used the popular consensus protocol proof-of-work(PoW).PoW has a well-known flaw:it distributes all rewards to a single miner(or pool)who inserts a new block.Consequently,the variance of rewards and the mining enter-prise risk are extremely high.In 2016,Shi proposed addressing this problem with a theoretical algorithm.We introduce an easily-implemented PoW variant that improves Shi’s idea.The network must not find a single nonce but a few to insert a block.This simple change allows for a fairer distribution of rewards and also has the effect of regularizing the insertion time of blocks.This method would facilitate the emergence of small pools or autonomous miners.

The predictive power of Bitcoin prices for the realized volatility of US stock sector returns

This paper is motivated by Bitcoin’s rapid ascension into mainstream finance and recent evidence of a strong relationship between Bitcoin and US stock markets.It is also motivated by a lack of empirical studies on whether Bitcoin prices contain useful information for the volatility of US stock returns,particularly at the sectoral level of data.We specifically assess Bitcoin prices’ability to predict the volatility of US composite and sectoral stock indices using both in-sample and out-of-sample analyses over multiple forecast horizons,based on daily data from November 22,2017,to December,30,2021.The findings show that Bitcoin prices have significant predictive power for US stock volatility,with an inverse relationship between Bitcoin prices and stock sector volatility.Regardless of the stock sectors or number of forecast horizons,the model that includes Bitcoin prices consistently outperforms the benchmark historical average model.These findings are independent of the volatility measure used.Using Bitcoin prices as a predictor yields higher economic gains.These findings emphasize the importance and utility of tracking Bitcoin prices when forecasting the volatility of US stock sectors,which is important for practitioners and policymakers.

Predicting Bitcoin Trends Through Machine Learning Using Sentiment Analysis with Technical Indicators

Predicting Bitcoin price trends is necessary because they represent the overall trend of the cryptocurrency market.As the history of the Bitcoin market is short and price volatility is high,studies have been conducted on the factors affecting changes in Bitcoin prices.Experiments have been conducted to predict Bitcoin prices using Twitter content.However,the amount of data was limited,and prices were predicted for only a short period(less than two years).In this study,data from Reddit and LexisNexis,covering a period of more than four years,were collected.These data were utilized to estimate and compare the performance of the six machine learning techniques by adding technical and sentiment indicators to the price data along with the volume of posts.An accuracy of 90.57%and an area under the receiver operating characteristic curve value(AUC)of 97.48%were obtained using the extreme gradient boosting(XGBoost).It was shown that the use of both sentiment index using valence aware dictionary and sentiment reasoner(VADER)and 11 technical indicators utilizing moving average,relative strength index(RSI),stochastic oscillators in predicting Bitcoin price trends can produce significant results.Thus,the input features used in the paper can be applied on Bitcoin price prediction.Furthermore,this approach allows investors to make better decisions regarding Bitcoin-related investments.

Bitcoin:Exploring Price Predictability and the Impact of Investor Sentiment

This article addresses the predictability of Bitcoin’s price by examining relationships between Bitcoin and financial and emotional variables such as the Fear and Greed Index(FGI),the American Interest Rate(FED),and the Stock Market Index(NASDAQ).Through the use of statistical techniques such as the Johansen Cointegration Test and Granger Causality,as well as forecasting models,the study reveals that,despite the notorious volatility of the cryptocurrency market,it is possible to identify consistent behavioral patterns that can be successfully used to predict Bitcoin returns.The approach that combines VAR models and neural networks stands out as an effective tool to assist investors and analysts in making informed decisions in an ever-changing market environment.

Implied volatility estimation of bitcoin options and the stylized facts of option pricing

The recently developed Bitcoin futures and options contracts in cryptocurrency derivatives exchanges mark the beginning of a new era in Bitcoin price risk hedging.The need for these tools dates back to the market crash of 1987,when investors needed better ways to protect their portfolios through option insurance.These tools provide greater flexibility to trade and hedge volatile swings in Bitcoin prices effectively.The violation of constant volatility and the log-normality assumption of the Black–Scholes option pricing model led to the discovery of the volatility smile,smirk,or skew in options markets.These stylized facts;that is,the volatility smile and implied volatilities implied by the option prices,are well documented in the option literature for almost all financial markets.These are expected to be true for Bitcoin options as well.The data sets for the study are based on short-dated Bitcoin options(14-day maturity)of two time periods traded on Deribit Bitcoin Futures and Options Exchange,a Netherlandsbased cryptocurrency derivative exchange.The estimated results are compared with benchmark Black–Scholes implied volatility values for accuracy and efficiency analysis.This study has two aims:(1)to provide insights into the volatility smile in Bitcoin options and(2)to estimate the implied volatility of Bitcoin options through numerical approximation techniques,specifically the Newton Raphson and Bisection methods.The experimental results show that Bitcoin options belong to the commodity class of assets based on the presence of a volatility forward skew in Bitcoin option data.Moreover,the Newton Raphson and Bisection methods are effective in estimating the implied volatility of Bitcoin options.However,the Newton Raphson forecasting technique converges faster than does the Bisection method.

A Covert Communication Method Using Special Bitcoin Addresses Generated by Vanitygen

As an extension of the traditional encryption technology,information hiding has been increasingly used in the fields of communication and network media,and the covert communication technology has gradually developed.The blockchain technology that has emerged in recent years has the characteristics of decentralization and tamper resistance,which can effectively alleviate the disadvantages and problems of traditional covert communication.However,its combination with covert communication thus far has been mostly at the theoretical level.The BLOCCE method,as an early result of the combination of blockchain and covert communication technology,has the problems of low information embedding efficiency,the use of too many Bitcoin addresses,low communication efficiency,and high costs.The present research improved on this method,designed the V-BLOCCE which uses base58 to encrypt the plaintext and reuses the addresses generated by Vanitygen multiple times to embed information.This greatly improves the efficiency of information embedding and decreases the number of Bitcoin addresses used.Under the premise of ensuring the order,the Bitcoin transaction OP_RETURN field is used to store the information required to restore the plaintext and the transactions are issued at the same time to improve the information transmission efficiency.Thus,a more efficient and feasible method for the application of covert communication on the blockchain is proposed.In addition,this paper also provides a more feasible scheme and theoretical support for covert communication in blockchain.

Bitcoin市场的长记忆性的实证分析

Bitcoin是一种新型的虚拟电子货币。运用初步的统计方法和R/S分析法分析其市场交易数据,对其长记忆性进行实证分析。分析结果表明,现阶段,Bitcoin的交易市场具有聚集性和持续性,当前的价格对于未来很长一段时间都有影响。

Analysis on the influence factors of Bitcoin’s price based on VEC model

Background:Bitcoin,the most innovate digital currency as of now,created since 2008,even through experienced its ups and downs,still keeps drawing attentions to all parts of society.It relies on peer-to-peer network,achieved decentralization,anonymous and transparent.As the most representative digital currency,people curious to study how Bitcoin’price changes in the past.Methods:In this paper,we use monthly data from 2011 to 2016 to build a VEC model to exam how economic factors such as Custom price index,US dollar index,Dow jones industry average,Federal Funds Rate and gold price influence Bitcoin price.Result:From empirical analysis we find that all these variables do have a long-term influence.US dollar index is the biggest influence on Bitcoin price while gold price influence the least.Conclusion:From our result,we conclude that for now Bitcoin can be treated as a speculative asset,however,it is far from being a proper credit currency.

The effect of propagation delay on the dynamic evolution of the Bitcoin blockchain

This paper analyzes the selfish-mine strategy in the Bitcoin blockchain introduced in 2013 by I.Eyal and E.G.Sirer.This strategy could be used by a colluding pool of miners to earn more than their fair share of the mining revenue and in consequence to force other honest miners to join them to decrease the variance of their revenues and make their monthly revenues more predictable.It is a very dangerous dynamic that could allow the rogue pool of miners to go toward a majority by accumulating powers of news adherents and control the entire network.Considering that the propagation delay of information between any two miners in the network,which is not negligible and follows a normal distribution with mean proportional to the physical distance between the two miners,and a constant variance independent of others'delays,we prove that no guarantee can be given about the success or failure of the selfish-mine attack because of the variability of information propagation in the network.

Dynamic spillovers between the term structure of interest rates,bitcoin,and safe‑haven currencies

This study examines the connectedness between the US yield curve components(i.e.,level,slope,and curvature),exchange rates,and the historical volatility of the exchange rates of the main safe-haven fiat currencies(Canada,Switzerland,EURO,Japan,and the UK)and the leading cryptocurrency,the Bitcoin.Results of the static analysis show that the level and slope of the yield curve are net transmitters of shocks to both the exchange rate and its volatility.The exchange rate of the Euro and the volatility of the Euro and the Canadian dollar exchange rate are net transmitters of shocks.Meanwhile,the curvature of the yield curve and the Japanese Yen,Swiss Franc,and British Pound act mainly as net receivers.Our static connectedness analysis shows that Bitcoin is mainly independent of shocks from the yield curve’s level,slope,and curvature,and from any main currency investigated.These findings hint that Bitcoin might provide hedging benefits.However,similar to the static analysis,our dynamic analysis shows that during different periods and particularly in stressful times,Bitcoin is far from being isolated from other currencies or the yield curve components.The dynamic analysis allows us to observe Bitcoin’s connectedness in times of stress.Evidence supporting this contention is the substantially increased connectedness due to policy shocks,political uncertainty,and systemic crisis,implying no empirical support for Bitcoin’s safe-haven property during stress times.The increased connectedness in the dynamic analysis compared with the static approach implies that in normal times and especially in stressful times,Bitcoin has the property of a diversifier.The results may have important implications for investors and policymakers regarding their risk monitoring and their assets allocation and investment strategies.

Predicting changes in Bitcoin price using grey system theory

Bitcoin is currently the leading global provider of cryptocurrency.Cryptocurrency allows users to safely and anonymously use the Internet to perform digital currency transfers and storage.In recent years,the Bitcoin network has attracted investors,businesses,and corporations while facilitating services and product deals.Moreover,Bitcoin has made itself the dominant source of decentralized cryptocurrency.While considerable research has been done concerning Bitcoin network analysis,limited research has been conducted on predicting the Bitcoin price.The purpose of this study is to predict the price of Bitcoin and changes therein using the grey system theory.The first order grey model(GM(1,1))is used for this purpose.It uses a firstorder differential equation to model the trend of time series.The results show that the GM(1,1)model predicts Bitcoin’s price accurately and that one can earn a maximum profit confidence level of approximately 98%by choosing the appropriate time frame and by managing investment assets.

Portfolio diversification benefits of alternative currency investment in Bitcoin and foreign exchange markets

This study examines the portfolio diversification benefits of alternative currency trading in Bitcoin and foreign exchange markets.The following methods are applied for the analysis:the spillover index method of Diebold and Yilmaz(Int J Forecast 28(1):57–66,2012.https://doi.org/10.1016/j.ijfor ecast.2011.02.006),the spillover asymmetry measures of Barunik et al.(J Int Money Finance 77:39–56,2017.https://doi.org/10.1016/j.jimon fin.2017.06.003),and the frequency connectedness method of Barunik and Křehlik(J Financ Econom 16(2):271–296,2018.https://doi.org/10.1093/jjfin ec/nby001).The findings identify the presence of low-level integration and asymmetric volatility spillover as well as a dominant role of short horizon spillover among Bitcoin markets and foreign exchange pairs for six major trading currencies(US dollar,euro,Japanese yen,British pound sterling,Australian dollar,and Canadian dollar).Bitcoin is found to provide significant portfolio diversification benefits for alternative currency foreign exchange portfolios.Alternative currency Bitcoin trading in euro is found to provide the most significant portfolio diversification benefits for foreign exchange portfolios consisting of major trading currencies.The findings of the study regarding spillover dynamics and portfolio diversification capabilities of the Bitcoin market for foreign exchange markets of major trading currencies have significant implications for portfolio diversification and risk minimization.

Bitcoin pricing: impact of attractiveness variables

The research seeks to contribute to Bitcoin pricing analysis based on the dynamics between variables of attractiveness and the value of the digital currency.Using the error correction model,the relationship between the price of the virtual currency,Bitcoin,and the number of Google searches that used the terms bitcoin,bitcoin crash and crisis between December 2012 and February 2018 is analyzed.The study also applied the same analysis to prices of Bitcoin denominated in different sovereign currencies traded during the same period.The Johansen(J Econ Dyn Control 12:231-254,1988)test demonstrates that the price and number of searches on Google for the first two terms are cointegrated.This research indicates that there are strong short-term and long-term dynamics among attractiveness factors,suggesting that an increase in worldwide interest in Bitcoin is usually preceded by a price increase.In contrast,an increase in market mistrust over a collapse of the currency,as measured by the term bitcoin crash,is followed by a fall in price.Intense world economic crisis events appear to have a strong impact on interest in the virtual currency.This study demonstrates that during a worldwide crisis Bitcoin becomes an alternative investment,increasing its price.Based on it,bitcoin may be used as a safe haven by the financial market and its intrinsic characteristics might help the investors and governments to find new mechanisms to deal with monetary transactions.

Bitcoin Network Measurement and a New Approach to Infer the Topology

Bitcoin has made an increasing impact on the world's economy and financial order,which attracted extensive attention of researchers and regulators from all over the world.Most previous studies had focused more on the transaction layer,but less on the network layer.In this paper,we developed BNS(Bitcoin Network Sniffer),which could find and connect nodes in the Bitcoin network,and made a measurement in detail.We collected nearly 4.1 million nodes in 1.5 hours and identified 9,515 reachable nodes.We counted the reachable nodes'properties such as:service type,port number,client version and geographic distribution.In addition,we analyzed the stability of the reachable nodes in depth and found nearly 60%kept stable during 15 days.Finally,we proposed a new approach to infer the Bitcoin network topology by analyzing the Neighbor Addresses of Adjacent Nodes and their timestamps,which had an accuracy over 80%.