## 4 Results and Discussion
### Emerging Digital Payment Technologies
#### 4.1.4 Cryptocurrencies  
Cryptocurrency is a form of digital currency secured by cryptography that makes it nearly impossible to counterfeit or double spend. Most cryptocurrencies are decentralized networks based on blockchain technology and are secured by encryption. There are 13 studies on cryptocurrencies out of 58 reviewed articles (Table 5 and Figures 2 and 3). These studies were concentrated in the US, EU, Russia and across international boundaries. The cryptocurrencies studied include Bitcoin, Digicash, DCC--Digital Community Currency (virtual)--ID-based blind signature scheme and other blockchain-based cryptocurrencies. For example, Bitcoin, as an emerging digital payment technology, is revolutionary in financial markets. It emerged as a peer-to-peer payment system combining modern cryptology and communications technology and can meet the need of decentralization, controlling of money supply, estimating the amount of money in circulation and reducing inflation. Some of the studies focused on the fluctuation in price and investment opportunities in digital cryptocurrencies represented by Bitcoin, e.g., [82], while other studies, e.g., [49], explored the characteristics of cryptocurrency and its potential vulnerabilities to money laundering (ML) and financing terrorism (FT) and recommended assessments of the risks associated with cryptocurrencies in terms of ML and FT against their functions in the financial system.  
Some of the studies evaluated user privacy in Bitcoin. For example, the privacy standard of Bitcoin in a university setting was investigated [76] and the findings revealed that the privacy measures offered by Bitcoin were inadequate to safeguard user privacy. Thus, the study recommended measures to enhance the privacy protection features of Bitcoin, which ultimately helped in reducing the concerns raised over the privacy issues of Bitcoin. Similarly, other studies explored the factors influencing consumers' adoption of Bitcoin as a form of payment, e.g., a study by [PERSON] et al. [74] showed significant factors, such as self-efficacy, transaction processing, securing and control and perceived trust for the adoption of Bitcoin. Additionally, they suggested further research on experience, age, gender and educational level [74]. The other form of cryptocurrency is virtual currency, referring to unregulated digital money created and owned by its developers and adopted by virtual community members. This type of digital money functions like any other currency in certain situations; however, it lacks some of the features of real money [78]. Thus, the DCCs are used for some transactions within a particular group of geographical locations or interest. A study by [PERSON] et al. [78] inspected 22 DCC platforms and identified 4 distinct groups of DCC, which contributed towards providing more knowledge to investigate a specific case of a DCC platform. It was reported that the use of DCC has been increasing because of financial crises and increased use of digital devices. For example, the Icelandic nationwide blockchain cryptocurrency \"Auuracoin\" was developed in response to the 2008 financial crisis [87]. Studies have also shown that even though DCC helps in social and financial inclusion, digital payment studies have not considered an in-depth study on DCC [78].