Shape Security, a cybersecurity startup that helps businesses prevent fraudulent use of their online systems, has raised $51 million in a round of funding led by C5 Capital, with participation from Kleiner Perkins, HPE Growth, Norwest Ventures Partners, Focus Ventures, JetBlue Technology Ventures, Top Tier Capital Partners, and Epic Ventures. As a result of this latest investment, Shape Security has also now entered the much-coveted “unicorn” club, claiming a valuation of $1 billion.