Cohen grew up in the Upper West Side of Manhattan, New York City as the son of a teacher and computer scientist. He claims he learned the BASIC programming language at the age of 5 on his family's Timex Sinclair computer. Cohen passed the American Invitational Mathematics Examination to qualify for the United States of America Mathematical Olympiad while he attended Stuyvesant High School in New York City. He is also an alumnus of the Hampshire College Summer Studies in Mathematics program. He graduated from Stuyvesant in 1993 and attended SUNY Buffalo. He later dropped out of college to work for several dot com companies throughout the mid to late 1990s, the last being MojoNation, an ambitious but ill-fated project he worked on with Jim McCoy. MojoNation allowed people to break up confidential files into encrypted chunks and distribute those pieces on computers also running the software. If someone wanted to download a copy of this encrypted file, they would have to download it simultaneously from many computers. This concept, Cohen thought, was perfect for a file sharing program, since programs like KaZaA take a long time to download a large file because the file is coming from one source. Cohen designed BitTorrent to be able to download files from many different sources, thus speeding up the download time, especially for users with faster download than upload speeds. Thus, the more popular a file is, the faster a user will be able to download it, since many people will be downloading it at the same time, and these people will also be uploading the data to other users. Cohen claims he has Asperger syndrome based on a self diagnosis.
BitTorrent
In April 2001, Cohen quit MojoNation and began work on BitTorrent. Cohen unveiled his novel ideas at the first CodeCon conference, which he and his roommate Len Sassaman created as a showcase event for novel technology projects after becoming disillusioned with the state of technology conferences. It remains an event for those seeking information about new directions in software, though BitTorrent continues to lay claim to the title of "most famous presentation". Cohen wrote the first BitTorrent client implementation in Python, and many other programs have since implemented the protocol. In the summer of 2002, Cohen collected free pornography to lure beta testers to use the program. BitTorrent gained its fame for its ability to quickly share large music and movie files online. Cohen has claimed he has never violated copyright law using his software. Regardless, he is outspoken in his belief that the current media business was doomed to being outmoded despite the RIAA and MPAA's legal or technical tactics, such as digital rights management. In May 2005, Cohen released a trackerless beta version of BitTorrent. In late 2003, Cohen had a short career at Valve working on Steam, their digital distribution system introduced for Half-Life 2. By 2004, he had left Valve and formed BitTorrent, Inc. with his brother Ross Cohen and business partner Ashwin Navin. In 2012 he announced a beta-version of BitTorrent Live for TV broadcasting through the Internet. Cohen left BitTorrent, Inc. in a day to day capacity to co-found Chia.Network in the fall of 2017.
By mid-2005, BitTorrent, Inc. was funded by venture capitalistDavid Chao from Doll Capital Management, and in late 2005 Cohen and Navin made a deal with the MPAA to remove links to illegal content on the official BitTorrent website. The deal was with the seven largest studios in America. The agreement means the site will comply with procedures outlined in the Digital Millennium Copyright Act.
Personal life
As of 2008, Cohen lives in the San Francisco Bay Area, United States, with his wife Jenna and their three children. Cohen's hobbies include original origami and juggling up to five balls, but his main interest is in recreational mathematics. Cohen maintains a blog where he frequently discusses trust metrics with Raph Levien, as well as money systems, games of skill, and other math-related topics. He is also an assembly puzzle enthusiast. He has designed several puzzles including some in conjunction with Oskar van Deventer including several gear-based puzzles such as Gear Shift and a multiple Rubik's Cube variant called Bram's Fortress. Some of Bram's puzzle designs are available for 3-D printing via Shapeways.
Awards
Cohen has received a number of awards for his work on the BitTorrent protocol. These awards include:
