Key Management
Last updated
Last updated
Advantages.
Fast and relatively secure.
Provides integrity and privacy.
The larger key length provides larger security.
Disadvantages.
Requires the share of a secret key.
How?
Complex administration and non-scalable.
It is needed to distribute the keys.
A key for each receiver.
Also known as PKE - public key encryption.
Advantages.
It is not needed to share secret keys à priori.
It is scalable and versatile.
Disadvantages.
Generally computationally intensive.
It may require a certificate of authority.
Private keys have to be confidential.
Alice and Bob agree on a prime number p and a base g.
Alice chooses the secret number a, and sends it to Bob (g^a modp).
ob chooses the secret number b, and sends it to Alice (g^b modp).
Alice calculates ((g^b modp)^a mod p).
Bob calculates ((g^a modp)^b mod p).
Alice and Bob use this value as their session key. p and g do not have to be protected.
Alice and Bob choose p = 23 e g = 5.
Alice chooses a = 6 and sends 56 mod 23 = 8.
Bob chooses b = 15 and sends 515 mod 23 = 19.
Alice calculates 196 mod 23 = 2.
Bob calculates 815 mod 23 = 2.
2 is the shared key.
