(or Data Encryption Standard), a (symmetric) block cipher using a 64 bit block size, with keys of size 56 bit, the standard US block cipher from 1976 to 2001.

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255 views

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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0answers
147 views

Method and explanation for calculating difference in speed between DES and RSA

Our assignment asks us to convert an RSA speed in bytes per second to a DES speed in bytes per second. Our professor's treatment of this ("RSA is 100 times slower than DES") seems insufficient. Could ...
2
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1answer
434 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?
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1answer
167 views

How to bring little changes in DES algorithm

I thought of implementing DES modes of operation as a project...But my guide asked to change or to modify the DES algorithm in such a way to overcome drawbacks of DES...So is there any way to do ...
5
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1answer
173 views

DES key expansion: why are these two descriptions different?

I would like someone to explain me how to generate DES subkeys, because in the documentation that I saw, sometimes they say: "We rotate the initial key according to the number of iterations given ...
2
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1answer
1k views

Brute force attack on DES + property of DES

In a brute force attack on DES, it seems to me that one plaintext-ciphertext pair suffices to launch the attack. (I.e. suppose we are given a message $x$ and a ciphertext $c$ such that $DES_k ( x ) = ...
1
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1answer
586 views

Traditional DES scheme in Unix crypt function

In a security context course, we need to reproduce the old DES hashing scheme in the crypt program, on an old unix system. I am actually reading the crypt page on wikipedia: The traditional ...
2
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1answer
228 views

Regarding matsui's Paper on Linear Cryptanalysis of DES

I's going throught the the Paper by Matsui on Linear Cryptanalysis of DES . In that he says $NS_{5}(16,15)=12$ And then in the next paragraph he says considering the expansion and permutation phases ...
30
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3answers
4k 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?
5
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1answer
239 views

S-box Cryptanalytic Resistance

In DES, different S-boxes were tested for cryptanalytic resistance and the most secure one was chosen for the algorithm itself. How do different S-boxes offer different levels of security against ...
3
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1answer
800 views

ANSI X9.9 Cryptography Standards

I'm trying to create a ISO8583 Rev93 message. What is the standard way of generating MAC key in ANSI X9.9 DES-CBC encryption algorithm is used to encrypt the ...
2
votes
2answers
463 views

DES Crack simulation

I wish to simulate an implementation of a DES Cracker using verilog. But every paper I read give only abstract hints but no concrete steps or how really to go about it. How is it usually done? For ...
2
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1answer
595 views

Verilog simulation of Data Encryption Standard

I interested in developing DES(in verilog) for my college project.Can i get help in understanding the simulation results of DES encryption and decryption ? thanks in advance .
4
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1answer
584 views

Linear Cryptanalysis

What is the principle of linear cryptanalysis, as applied to a block cipher ? For instance, this page gives the rough outline of differential cryptanalysis.
2
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2answers
299 views

How can I encrypt more than 64 bit with the Data Encryption Standard?

The Data Encryption Algorithm is designed to encipher and decipher blocks of data consisting of 64 bits under control of a 56-bit key. If my data is more than 64 bits, (suppose 66 or 67 bits), will ...
5
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1answer
2k views

What are the details of the DES weakness of reusing the same IV in CBC mode with the same key?

I think I once faced the recommendation, that the initialization vector should always be random and never be used twice with the same key. How serious is this weakness? Also, is AES less effected ...
17
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2answers
2k views

How were the DES S-box values determined?

It seems like the S-boxes in DES have essentially random values. How were these chosen?