This paper is about the design of multivariate public key schemes, as well as block and stream ciphers, in relation to recent attacks that exploit various types of multivariate algebraic relations. We survey these attacks focusing on their common fundamental principles and on how to avoid them. From this we derive new very general design criteria, applicable for very different cryptographic com...

In this note we refer to the security of the Py and TPy families, as discussed in several papers in recent years. We investigate the published attacks, and show that no attacks on TPy, TPypy and TPy6 have ever been published, whose complexities are within the bounds set by the security claims of these ciphers. Also, only a single attack on Py was published which may be considered within the sco...

Rabbit is a software-oriented synchronous stream cipher with very strong security properties and support for 128-bit keys. Rabbit is part of the European Union’s eSTREAM portfolio of stream ciphers addressing the need for strong and computationally efficient (i.e., fast) ciphers. Extensive cryptanalysis confirms Rabbit’s strength against modern attacks; attacks with complexity lower than an exh...

Stream ciphers play an important role in those applications where high throughput remains critical and resources are very restricted e.g. in Europe and North America, A5/1 is widely used stream cipher that ensure confidentiality of conversations in GSM mobile phones. However careful security analysis of such cipher is very important due to widespread practical applicability. The basic building ...

Tree-structures have been proposed for both the construction of block ciphers by Kam and Davida 7], and self-synchronous stream ciphers by K uhn 9]. Attacks on these ciphers have been given by An-derson 2] and Heys and Tavares 6]. In this paper it is demonstrated that a more eecient attack can be conducted when the underlying Boolean functions for the cells are known. It is shown that this atta...

d-Monomial tests are statistical randomness tests based on Algebraic Normal Form representation of a Boolean function, and were first introduced by Filiol in 2002. We show that there are strong indications that the Gate Complexity of a Boolean function is related to a bias detectable in a d-Monomial test. We then discuss how to effectively apply d-Monomial tests in chosen-IV attacks against str...