With that constraint, you get an easily invertible cipher structure, with the Now, to get a secure and efficient cipher, well, that takes a bit more. Virtually all conventional block encryption algorithms including data encryption standard (DES) are based on Feistel Cipher Structure. The plaintext is divided. He and a colleague, Don Coppersmith, published a cipher called Lucifer in that was the first public example of a cipher using a Feistel structure. Due to the.

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By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service. I’m getting confused of what is the actual structure of the key generation and the round function algorithms that Feistel cipher uses. I have been reading many resources about block cipher.

All resources starts talking about Feistel cipher, but non of them explains how the key generation and the round function work.

Feistel Block Cipher

They all suddenly jump to explain The DES method. So, are the key generation and the round function of Feistel cipher same as DES cipher? Sorry for the many questions, but I really confused. This is important as that’s what’s confusing you.

It’s just that DES is extremely prominent in the literature so articles are drawn towards it. The following is two Feistel rounds ostensibly just a single round as they have to be in LH and RH pairs: This is also important in that this is the super set.

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And being so, there is no particular architecture for either the function or the key schedule that generates the round keys. DES architecture is just what the designers thought up to create it. I’m just a country boy and not a cryptographer, but as I understand it the overall security of a Feistel network will be proportional to the security of the key schedule times the security of function.

Approximately, but you get the idea.

It is possible to use anything from a strong hash function to simple compression techniques for function This will directly affect the security requirements for the key schedule. It is interesting to note that whilst there are proven architectures for Feistel compression functions and indeed native block ciphers like substitution and permutationthere are no equivalent standardised architectures for a key schedule. Feisel can have anything, ranging from Blowfish’s computationally expensive method, through AES’ to the dodgy striping technique of RC4.

The basic requirement of the key schedule even more important than security is that the key can be repetitively slotted into the main architecture at the correct bit width.

Otherwise, it won’t even begin to work. There are of course certain fundamental requirements for both, and these are too extensive to list here. Structkre that you know the nature of these two fundamental components, you can do your own research. Look at things like: Are there any specific requirements for strructure function FF in a Feistel cipher? Questions about key schedules.

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Feistel Cipher Structure

Implementation detail of Feistel networks featuring Blowfish. By clicking “Post Your Answer”, you acknowledge that you have read our updated terms of serviceprivacy policy and cookie policyand that your continued use of the website is subject to these policies.

Home Questions Tags Users Unanswered. Feistel cipher key generation and round function algorithms Ask Question. Paul Uszak 7, 1 15 srructure You saved me of reading many boring articles.

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