Improving key stream generation for sosemannk stream cipher using two fish block cipher

Dissertant

Muhammad, Rana Sad

University

University of Technology

Faculty

-

Department

Computer Sciences Department

University Country

Iraq

Degree

Ph.D.

Degree Date

2008

English Abstract

Cryptographic techniques play an important role in network security and stream ciphers are one of the main cryptographic techniques that play a very important pan in maintaining security and protecting valuable information from potential misuse. This thesis will introduce updated concepts to stream cipher which are: let the size of slates in LFSR equal to 32 bits rather than 1 bit, let the block cipher algorithm generate initial values of states in LFSR, let the linear complexity of LFSR increased by using key-dependent Sboxes which are derived from block cipher algorithm with using FSM, Also this thesis will introduce two proposal algorithms (Snowfish 1) and the (Snowfish 2) to improve the Sosemanuk stream cipher algorithm by benefiting from the efficient properties of the Two fish block cipher and also use its key schedule, key-dependent Sbox to increase the security, randomness and try to avoid the guess and determine attack of Sosemanuk.

These two proposals use Two fish algorithm rather than Serpent algorithm which was used in the Sosemanuk and also they use key-dependent Sbox rather than static Sbox, They are similar in the same key length (128 to 256 bit), IV length (128 bit), LFSR, FSM and output transformation. This thesis is implemented using Visual Basic 6, 0 language on PC computer type P4 with RAM 504 MB and 2.00 GHz with Intel processor to perform these two proposed systems and also to perform the Sosemanuk system to make a comparison between them by using the tests of randomness, the structural tests and the complexity of the algorithm.

These tests give results that shows the two proposed systems have good results in increasing the security and randomness compared

Main Subjects

Information Technology and Computer Science

Topics

• Writing
• Encryption
• Computer networks
• Symbolism
• Security measures
• Data

• APA
• MLA
• AMA

Language

English

Data Type

Arab Theses

Record ID

BIM-305152