des

Paper: Testing Randomness in Ciphertext of Block-Ciphers Using DieHard Tests

Posted on April 25, 2010 by Publications 0

ABSTRACT
One of the important aspects of the security of block ciphers is the randomness of the cipher text. One criterion used to evaluate the Advanced Encryption Standard (AES) candidate algorithms was their demonstrated suitability as random number generators.
In this paper, we introduced a new approach to interpret the results of tests of randomness. This approach relies on using DieHard battery of tests which was designed originally to test the randomness of Random Number Generators (RNGs). The proposed approach was used to test the randomness of five types of data; plaintext, 3DES-encrypted, AES-encrypted, Serpent-encrypted, and Blowfish-encrypted. The tests resulted in 47 p-values for each type of data. This paper suggests the classification of results of DieHard tests into three areas; Safe Area, Doubt Area, and Failure Area. The resulting p-values for each data type were distributed over these areas according to the suggested ranges. The data type having more p-values in the Safe Area indicate better randomness, while the existence of many p-values in the Failure Area indicates deviation from randomness. The results of the implemented tests showed that AES- and Blowfish-encrypted data provided equal results in term of number of p-values distributed over different areas. The AES and Blowfish results were slightly better than Serpent-encrypted data while 3DES encrypted data had more p-values in the Doubt Area.

Citation Information:

Mohammed M. Alani, Testing Randomness in Ciphertext of Block-Ciphers Using DieHard Tests, International Journal of Computer Science and Network Security (IJCSNS), Vol.10, No.4, April 2010, pp. 53-57.

Paper: DES96 – Improved DES Security

Posted on April 21, 2010 by Publications 0

ABSTRACT

The Data Encryption Standard (DES) has shown noticeable signs of aging during the last two decades. In this paper we develop a system that is a DES-variant with more resistance towards the possible attacks against DES. The developed system has a sub-key generation algorithm that is completely different from the original DES.
The developed system uses 84-bit initial key instead of the 56-bit key originally used. It has substitution boxes inside the key generation algorithm and mod2 additions. The choice of arrangement of substitution boxes in the main algorithm for each round is sub-key dependent. The result of the design is a DES-variant cryptographic system that has higher resistance against brute-force attack, differential cryptanalysis, and linear cryptanalysis. The proposed system design also cancelled the weak-keys and complement keys properties of the DES.

Index Terms – data encryption standard, encryption, cryptanalysis.

Citation Information:

Mohammed M. Alani, DES96 – Improved DES Security,  Proceedings of the 7th IEEE International Multi-Conference on Systems, Signals and Devices (SSD’10) , Amman, Jordan. June 2010. (IEEEXplore).

Paper: DES80 – A DES Variant Cryptographic System

Posted on April 15, 2010 by Publications 0

ABSTRACT

The Data Encryption Standard (DES) has shown noticeable weaknesses during the last decade. In this paper we develop a system that is a DES-variant but has more resistance towards the latest attacks against DES. The developed system has a sub-key generation algorithm that is totally different from the original DES one. The developed system uses a 70-bit initial key instead of the 56-bit key originally used. It has substitution boxes inside the key generation algorithm and mod2 addition. The choice of arrangement of substitution boxes in the main algorithm for each round is sub-key dependent. The result of our design is a DES-variant cryptographic system that has higher resistance towards brute-force attack, differential cryptanalysis, and linear cryptanalysis. Our design also canceled the weak-keys and complement-keys properties of the DES.
Citation Information:

Abdul-Karim A-R. Kadhim, Mohammed M. Alani, DES80: A DES-Variant Cryptographic System, published in the First Scientific Conference of the State Company of Internet Services, Baghdad, Oct. 22nd -23rd , 2002.

 Full Text (PDF)

Note: By the time we were working on this paper in the years 2000-2001, we had very limited Internet connectivity in Iraq. This lead to the fact that we did not know about the Canadian DES80 project at all. If we knew, we would have changed the name of the paper accordingly.

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