Week 7: 2
4-2023 NT219–Cryptography
Stream Cipher Review
𝐶←𝑀⊕𝐾
Chaotic
system for ex.
How to negotiate?
Attacks (chosen plaintext attacks):
One-time key!
Week 7: 3
4-2023 NT219–Cryptography
DES review
DES: 64-bits block cipher
Key spaces: possible keys
Brute Force attacks
https://en.wikipedia.org/wiki/Data_Encryption_Standard
Unsecure!
Choosen
plaintext attacks!
Week 7: 4
4-2023 NT219–Cryptography
A E S review
substitute-bytes (sub)
Non-linear operation based on a defined substitution box
Used to resist cryptanalysis and other mathematical attacks
shift-rows (shr)
Linear operation for producing diffusion
mix-columns (mic)
Elementary operation also for producing diffusion
add-round-key (ark) (128, 192, 256 bits)
Simple set of operations on state matrices ⊕
Linear operation
Produces confusion
Week 7: 5
4-2023 NT219–Cryptography
Dynamic AES?
Negotiate
the secret
key?
