Key distribution studies how do people/entities get the keys they need to communicate securely.
Dolev-Yao Model
In the following we always assume the Dolev-Yao model for attacker
The attacker under the Dolev-Yao model Has full control over the network
- The attacker carries the message
- Can eavesdrop on any message
- Delay, delete, modify, replay, and inject messages
But limited by cryptography
- Cannot modify integrity-protected message without the receiver noticing
- Cannot decrypt the encrypted message
The problem of key distribution
In Body’s theorem, without a secure, pre-existing channel, two entities cannot reliably establish an authenticated session directly.
Why not Diffie-Hellman
Diffie-Hellman Key Exchange enables two parties to create a shared secret over an insecure channel, but its security depends on the type of attacker present. Diffie-Hellman (DH) is secure if the attacker is passive; with an active attacker, we need to protect the DH key exchange with some form of origin authentication.
- Passive attacker
- A passive attacker can listen to the messages exchanged during