Swarm Intelligence based linear cryptanalysis of four-round Data Encryption Standard algorithm

Author(s):  
Anjali Dadhich ◽  
Abhishek Gupta ◽  
Surendra Yadav
2016 ◽  
Vol 16 (4) ◽  
pp. 3-12 ◽  
Author(s):  
Yuri Borissov ◽  
Peter Boyvalenkov ◽  
Robert Tsenkov

Abstract We investigate the effect of inserting extra linearity in the Data Encryption Standard (DES) through appropriate nonsingular linear encodings of the output of the individual S-boxes. More specifically, we examine the general situation when the output of each S-box of the DESis precoded separately intoaproperly constructed copy of the inherent even-weight code of length 4. The study is focused on finding multi-round linear characteristics for thus modified DESciphers having maximal effectiveness. Depending on the particular encodings, it turns out that the effectiveness of interest may be larger but in most cases is smaller than that one for the original DESwith the same number of rounds. The latter means that the complexity of successful linear cryptanalysis against these ciphers will mainly increase comparing to the DESitself. The present research extends inanatural way our previous work[Linear Cryptanalysis and Modified DESwith Parity Check in the S-boxes, LNCS 9540 (2016), pp. 60-78].


Author(s):  
Mays M. Hoobi

The Internet is providing vital communications between millions of individuals. It is also more and more utilized as one of the commerce tools; thus, security is of high importance for securing communications and protecting vital information. Cryptography algorithms are essential in the field of security. Brute force attacks are the major Data Encryption Standard attacks. This is the main reason that warranted the need to use the improved structure of the Data Encryption Standard algorithm. This paper proposes a new, improved structure for Data Encryption Standard to make it secure and immune to attacks. The improved structure of Data Encryption Standard was accomplished using standard Data Encryption Standard with a new way of two key generations. This means the key generation system generates two keys: one is simple, and the other one is encrypted by using an improved Caesar algorithm. The encryption algorithm in the first 8 round uses simple key 1, and from round 9 to round 16, the algorithm uses encrypted key 2. Using the improved structure of the Data Encryption Standard algorithm, the results of this paper increase Data Encryption Standard encryption security, performance, and complexity of search compared with standard Data Encryption Standard. This means the Differential cryptanalysis cannot be performed on the cipher-text.


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