[...] two of the biggest boosters of the virtual currency, Cameron and Tyler Winklevoss, are trying to firm up support by creating the first regulated bitcoin exchange for American customers — what they are calling the Nasdaq of bitcoin. The brothers, who received $65 million in Facebook shares and cash in 2008 after jousting with its founder, Mark Zuckerberg, have hired engineers from top hedge funds, enlisted a bank and engaged regulators with the aim of opening their exchange — named Gemini, Latin for twins — in the coming months. The exchange, which the twins have financed themselves, is a risky bet, given that the virtual currency industry has been a target of hackers and has faced existential questions about its legitimacy. Since being created in 2009, by someone going by the name of Satoshi Nakamoto, bitcoin has become a technology and financial industry phenomenon. The Winklevosses were swept up in the scandals when the chief executive officer of a bitcoin company they had invested in was arrested on charges related to money laundering in early 2014 — a result of activities that happened before they invested. The Gemini staff is working at a few rows of desks in the Winklevoss Capital offices in New York, which has dry-erase boards on the walls covered in math equations and strategic scribbles, and the requisite bean bag chair. Security experts hired by the Winklevoss twins, like those at many other bitcoin companies, have been focusing on ways to keep those keys in locations where they are offline and physically guarded.