Grain and Trivium are two hardware oriented synchronous stream ciphers proposed as the simplest candidates to the ECRYPT Stream Cipher Project, both dealing with 80-bit secret keys. In this paper we apply the linear sequential circuit approximation method to evaluate the strength of these stream ciphers against distinguishing attack. In this approximation method which was initially introduced b...

Grain and Trivium are the hardware-oriented finalists of the eSTREAM. They are both based on nonlinear feedback shift registers. In this paper, we study their generalized classes of nonlinear feedback shift registers with time varying feedback functions, namely, Grain-like and Trivium-like structures. Some interesting results regarding their periods are obtained.

The Fibonacci-to-Galois transformation is useful for reducing the propagation delay of feedback shift register-based stream ciphers and hash functions. In this paper, we extend it to handle Galois-to-Galois case as well as feedforward connections. This makes possible transforming Trivium stream cipher and increasing its keystream data rate by 27% without any penalty in area. The presented trans...

We study a new representation of non-linear multivariate equations for algebraic cryptanalysis. Using a combination of multiple right hand side equations and binary decision diagrams, our new representation allows a very efficient conjunction of a large number of separate equations. We apply our new technique to the stream cipher Trivium and variants of Trivium reduced in size. By merging all e...

This paper develops two methods for exploring the structure of the stream cipher TRIVIUM. We consider whether it is possible to compute the algebraic normal form (ANF) of such functions. Since the key and the IV together make up 160 variables, doing this directly is not possible. Instead, one can choose a subset of the key and IV variables of size n and fix the other variables to constants. As ...

Bu çalışmada yazılımsal trivium yapısı oluşturulmuştur. Trivium, 3 adet LFSR’nin (Doğrusal geri beslemeli kaydırmalı yazmaç) çeşitli mantık kapılarıyla birbirine bağlanmasıyla oluşturulan ve rasgele sayı üreteci olarak kullanılan yapılardan biridir. Trivium yapıları donanımsal veya oluşturulabilir. Yazılımsal yapılarının ilk değerlerini (anahtar, başlangıç vektörü LFSR içerikleri) belirlemek iç...

Combining different cryptanalytic methods to attack a cryptosystem became one of the hot topics in cryptanalysis. In particular, algebraic methods in side channel and differential fault analysis (DFA) attracted a lot of attention recently. In [9], Hojśik and Rudolf used DFA to recover the inner state of the stream cipher Trivium which leads to recovering the secret key. For this attack, they re...

This paper provides a comparison of the two stream cipher proposals Grain and Trivium which are candidates in the hardware focus phase of the eSTREAM project. We evaluate these algorithms concerning their feasibility to implement them for low-power applications in RFID systems. A triple of parameters which includes the chip area, the power consumption, and the number of clock cycles for encrypt...

One of the eSTREAM final portfolio ciphers is the hardwareoriented stream cipher Trivium. It is based on 3 nonlinear feedback shift registers with a linear output function. Although Trivium has attached a lot of interest, it remains unbroken by passive attacks. At FSE 2008 a differential fault analysis of Trivium was presented. It is based on the fact that one-bit fault induction reveals many p...

Cube attacks can be used to analyse and break cryptographic primitives that have an easy algebraic description. One example for such a primitive is the stream cipher Trivium. In this article we give a new framework for cubes that are useful in the cryptanalytic context. In addition, we show how algebraic modelling of a cipher can greatly be improved when taking both cubes and linear equivalence...