Banks, Facebook, Twitter and Google use epic numbers - based on prime factors - to keep our Internet secrets. This is RSA public-key encryption.

This video features Dr James Grime (http://singingbanana.com/). Message from James: "Thanks to Dr Chris Hughes of the University of York who showed me how to find the RSA public key from my browser, and showed me how awesome they look when you print them out."

The brown paper from this video can be purchased on ebay: http://www.ebay.co.uk/itm/221164184385

Thanks to Drew Mokris for the animation: http://www.spinnerdisc.com/

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Videos by Brady Haran