A way, esp. one of several possible variations, in which a set or number of things can be ordered or arranged.
24
votes
3answers
3k 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?
7
votes
1answer
458 views
Replacing the Rijndael S-Box?
The Rijndael S-Box design generates a permutation cycle of type $2+27+59+81+87$. What effect would replacing that permutation with a cycle of type $256$ have on the security of AES?
5
votes
1answer
935 views
Permutations of pseudorandom data
Assuming a bit string is deemed cryptographically secure, e.g. PRNG using AES in counter mode, can we equally assume any permutation of said bit string is also cryptographically secure?
In a more ...
4
votes
4answers
212 views
What is the difference between a hash and a permutation?
As defined by Wikipedia a hash function is
[...] any algorithm or subroutine that maps large data sets of variable length to smaller data sets of a fixed length. For example, a person's name, ...
2
votes
1answer
82 views
How do we find the last two correspondences in an otherwise known even permutation?
A secret even permutation $P$ of the set of non-negative integers less than $n$ is chosen. That might be a Feisltel cipher with a random key.
We are given in sequence the $P(x)$ for $x$ from $0$ to ...
1
vote
1answer
57 views
What is total key space in transposition algorithms
How we can measure key space in transposition algorithms? Should we specify the method, like rail fence ?
1
vote
1answer
144 views
How can I prove in zero knowldege that an ElGamal shuffle is correct for a special setting? [closed]
In a special ElGamal encryption scheme, every user has an ElGamal encryption key-pair using the same cyclic group $G$ and generator $g$.
The system has a special function :
$$ ...
0
votes
2answers
229 views
Making a cipher (ex: Vigenere) harder to break
The Vigenere cipher can relatively easy be broken when the key size is small compared to the size of the message. One first finds the length of the key, and then uses frequency analysis to actually ...
