Tagged Questions
1
vote
1answer
170 views
Can we replace the XOR operation in DES with some other operation?
Can we replace the XOR operation in the DES algorithm with some other operation? If so, does it work for both encryption and decryption?
10
votes
2answers
992 views
Why is MixColumns omitted from the last round of AES?
All rounds of AES (and Rijndael) have a MixColumns step, save the last round which omits it. DES has a similar feature where the last round differs slightly. The rationale, if I recall correctly, ...
5
votes
1answer
1k views
Avalanche effect in DES
I couldn't understand the avalanche effect in DES. Could someone explain how avalanche effect happens in DES
10
votes
2answers
3k views
How long does it take to crack DES and AES?
Suppose that a single evaluation of a block-cipher (DES or AES) takes 10 operations, and the computer can do $10^{15}$ such operations per second.
How long would it take for to recover a DES key, ...
24
votes
3answers
2k views
What are the benefits of the two permutation tables in DES?
Why do we use a permutation table in the first step of DES algorithm and one at the end of algorithm?
