A feistel-network or feistel cipher is a structure that has been used to create a number of different block ciphers (e.g., DES, Blowfish, Twofish, RC6).
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May the problem with DES using OFB mode be generalized for all feistel ciphers
There is a problem with using DES as the block cipher in OFB mode, eg: the feedback that goes back into the next round will be encrypted with the same key $k$ resulting back into the plaintext IV used ...
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Understanding a Blowfish cryptanalysis
I'm reading a cryptanalysis on Blowfish, and I've come across something that I don't quite get. Let's denote
$$\delta = a \oplus a'$$
where a and a' are bytes that cause a collision in some S-box ...
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Low complexity implementation of a small blocksize cipher (< 64 bit)
Searching for "small blocksize cipher" finds a number of discussions on the topic, mostly refering to FPE.
This one in particular suggests using AES as the round function of a Feistel network.
The ...
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Could the Enigma algorithm be classified as a Feistel network?
The Enigma algorithm is a encryption method that was developed (I believe) by the Germans in WWII. It went a little something like this:
When a letter was typed on the keyboard of the Enigma ...
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Differential cryptanalysis - breaking the last round of FEAL4?
I've been trying to learn cryptanalysis. I've come across this resource which proved very helpful:
http://theamazingking.com/crypto-feal.php
So far I've been almost successful in breaking FEAL4 ...
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Are there any specific requirements for the function $F$ in a Feistel cipher?
In a Feistel cipher (as shown below), it seems that the security of the cipher would be entirely dependent upon the function $F$. What requirements on $F$ are necessary for a secure Feistel cipher? Is ...
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Avalanche effect in DES
I couldn't understand the avalanche effect in DES. Could someone explain how avalanche effect happens in DES
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Does unbalancing a feistel cipher always improve security? Does it improve security at all?
So according to wikipedia unbalanced feistel ciphers provide greater provable security. Specifically, they state:
The Thorp shuffle is an extreme case of an unbalanced Feistel cipher in which one ...
