Privacy campaigners have criticised WhatsApp vulnerability as a 'huge threat to freedom of speech', and warned about potential exploitation by government agencies. Media reported that WhatsApp's security vulnerability can be used to allow Facebook and others to intercept and read encrypted messages. Facebook denied clams, saying "no one can intercept WhatsApp messages, not even the company and its staff, ensuring privacy for its billion-plus users". Open Whisper Systems, who developed end-to end encryption protocol of Signal now used also by WhatsApp, responded "There is no WhatsApp 'backdoor". Final response explaining the claim, came from Tobias Boelter, the man who discovered and reported the vulnerability to Facebook in April 2016.