Protocols Flashcards
In Alice-Bob notation, what does Sb() mean?
Signed by Bob
In Alice-Bob notation, what does Ea() mean?
Encrypted using Alice’s public key
In Alice-Bob notation, what does {}Kx mean?
Symmetric encrypted using shared key x
In Alice-Bob notation, what does #() mean?
A hash of the contents of the backets
What does it mean when a protocol has forward secrecy?
The protocol keeps the message secret from an attacker who has a recording of the protocol run and the long term keys of the people communicating.
What is does it mean when a protocol has mutual belief?
Both parties verify the identity of the other party
How does Diffie-Hellman work?
Both parties agree on two public parameters, generator (g) and a prime number (p).
Both parties pick random numbers (N)
Both parties calculate g^N mod p.
Both parties exchange their calculations.
The key is g^(Na * Nb) mod p
How does elliptic curve diffie-hellman work?
Both parties agree on a curve
They agree on a point p
Alice picks random n and sends np to Bob
Bob picks random m and sends mp to Alice
Both can then calculate mnp
What’s the difference in results between diffe-hellman and eliptic-curve diffe-hellman?
Diffe-hellman produces long keys slowly.
Eliptic-curve diffe-hellman produces short keys quickly
What is the problem with WPA 2?
Key is a hash of client nonce, access point nonce and access point password. Both nonces are public, therefore possible to brute force the password offline.
