Bitcoin is often associated with illegal activity and the dark corners of the Internet. But the Winklevoss twins believe their new exchange will help investors get involved with the digital currency safely and legally.

Cameron and Tyler Winklevoss, famous for their legal spat with Facebook founder Mark Zuckerberg, launched bitcoin exchange Gemini on Thursday. While the currency has received criticism for its role in exchanges such as online black market Silk Road, the brothers contend they have established sufficient safeguards to unlock its potential.

"We built with a security mentality from Day One," said Tyler Winklevoss.