Cryptanalysis of Cryptographic Primitives and Related Topics
Seyed Mehdi Mohammad Hassanzadeh · NORA - Norwegian Open Research Archives · 2011
This thesis has focused on the cryptanalysis of cryptographic primitives especially stream ciphers which is an important topic in cryptography. Additionally, the security of network coding is discussed and improved with a new scheme. First, a new statistical test, called Quadratic Box-Test, is presented. It can be used to evaluate the randomness quality of the pseudorandom sequences which can be the output of a cryptographic primitive. Moreover, it can be used as a distinguisher to attack stream ciphers, block ciphers and hash functions. In the second part of the thesis, some stream ciphers are analyzed and some successful attacks are presented. A modified algebraic attack is used against some clock controlled stream ciphers. In order to have successful attacks, the modified algebraic attack is accompanied by some new ideas. Moreover, the security of clock controlled stream ciphers based on its jumping system is investigated and discussed which resulted in some recommendations to design a clock controlled stream cipher. Finally, a differential distinguishing attack based on a fault attack is presented in this thesis to attack the Shannon stream cipher. The last part of this thesis focuses on the security of network coding which promises increased efficiency for future networks. For secure network coding, a new attack model is studied and the secrecy capacity is improved by a concatenated secret sharing scheme.