http://ocw.cs.pub.ro/courses/ 2026-05-28T16:49:36+03:00 http://ocw.cs.pub.ro/courses/ http://ocw.cs.pub.ro/courses/lib/tpl/arctic/images/favicon.ico text/html 2016-04-26T11:35:30+03:00 http://ocw.cs.pub.ro/courses/sasc/res/stuff?rev=1461659730&do=diff Diverse exercitii Feistel networks How can you distinguish a cipher composed only of a Feistel network from a random function if it has only (a) one round, (b) two rounds? For clarity, here is an image of such a cipher with two rounds: Decryption modes A sequence of plaintext blocks M1, . . . , M8 is encrypted using DES into a sequence of ciphertext blocks. Where an IV is used, it is numbered C0. A transmission error occurs and one bit in ciphertext block C3 changes its value. As a consequ… text/html 2017-03-19T23:46:30+03:00 http://ocw.cs.pub.ro/courses/sasc/res/tema1?rev=1489959990&do=diff Homework 1 Exercise 1 Let's analyse some substitution-permutation networks (SPN). SPN 1 (3p) We have the SPN from this figure: where S denotes the AES S-box (we'll discuss this in some detail during the next lecture), and 'Permutation' is a simple permutation block that simply shifts the input 4 bits to the right as in a queue. Both this S-box and the permutation are invertible and known by the attacker (you). Each input (x1, x2) is 8-bit (1 byte), as well as the keys k1, k2, and the outpu… text/html 2016-04-25T12:11:49+03:00 http://ocw.cs.pub.ro/courses/sasc/res/tema2?rev=1461575509&do=diff Homework 2 Terminati problema din laboratorul 6: <http://ocw.cs.pub.ro/courses/sasc/laboratoare/06> Ca si cu tema precedenta, va rog foarte mult sa nu copiati. Este o tema individuala. Cei care copiati veti avea punctaj 0.