Firefox blocks websites with vulnerable encryption keys

To protect users from cryptographic attacks that can compromise secure web connections, the popular Firefox browser will block access to HTTPS servers that use weak Diffie-Hellman keys.Diffie-Hellman is a key exchange protocol that is slowly replacing the widely used RSA key agreement for the TLS  (Transport Layer Security) protocol. Unlike RSA, Diffie-Hellman can be used with TLS's ephemeral modes, which provide forward secrecy -- a property that prevents the decryption of previously captu