forward secrecy
termcryptographysecurity
Stands for: Perfect Forward Secrecy (PFS)
A property that keeps past sessions safe even if the server's long-term key is later stolen.
With forward secrecy, each session negotiates a fresh ephemeral key that is thrown away afterward, so compromising the server tomorrow cannot decrypt recordings of today's traffic. Modern TLS defaults to it; it is why capturing encrypted traffic to "decrypt later" mostly does not work.
Also known as: pfs, perfect forward secrecy, forward-secrecy