(credit: Yuri Samoilov/Flickr) A surprisingly big number of top-name websites—Facebook and PayPal among them—recently tested positive for a critical, 19-year-old vulnerability that allowed attackers to decrypt encrypted data and sign communications using the sites' secret encryption key. The vulnerability in the transport layer security protocol for Web encryption was disclosed in 1998 when researcher Daniel Bleichenbacher found it in the TLS predecessor known as secure sockets layer.