Cryptanalysis of ARMADILLO2

Abstract. ARMADILLO2 is the recommended variant of a multi-purpose cryptographic primitive dedicated to hardware which has been proposed by Badel et al. in [1]. In this paper, we describe a meet-in-themiddle technique relying on the parallel matching algorithm that allows us to invert the ARMADILLO2 function. This makes it possible to perform a key recovery attack when used as a FIL-MAC. A variant of this attack can also be applied to the stream cipher derived from the PRNG mode. Finally we propose a (second) preimage attack when used as a hash function. We have validated our attacks by implementing cryptanalysis on scaled variants. The experimental results match the theoretical complexities. In addition to these attacks, we present a generalization of the parallel matching algorithm, which can be applied in a broader context than attacking ARMADILLO2

Survey on Lightweight Primitives and Protocols for RFID in Wireless Sensor Networks

The use of radio frequency identification (RFID) technologies is becoming widespread in all kind of wireless network-based applications. As expected, applications based on sensor networks, ad-hoc or mobile ad hoc networks (MANETs) can be highly benefited from the adoption of RFID solutions. There is a strong need to employ lightweight cryptographic primitives for many security applications because of the tight cost and constrained resource requirement of sensor based networks. This paper mainly focuses on the security analysis of lightweight protocols and algorithms proposed for the security of RFID systems. A large number of research solutions have been proposed to implement lightweight cryptographic primitives and protocols in sensor and RFID integration based resource constraint networks. In this work, an overview of the currently discussed lightweight primitives and their attributes has been done. These primitives and protocols have been compared based on gate equivalents (GEs), power, technology, strengths, weaknesses and attacks. Further, an integration of primitives and protocols is compared with the possibilities of their applications in practical scenarios

Algebraic Cryptanalysis of Deterministic Symmetric Encryption

Deterministic symmetric encryption is widely used in many cryptographic applications. The security of deterministic block and stream ciphers is evaluated using cryptanalysis. Cryptanalysis is divided into two main categories: statistical cryptanalysis and algebraic cryptanalysis. Statistical cryptanalysis is a powerful tool for evaluating the security but it often requires a large number of plaintext/ciphertext pairs which is not always available in real life scenario. Algebraic cryptanalysis requires a smaller number of plaintext/ciphertext pairs but the attacks are often underestimated compared to statistical methods. In algebraic cryptanalysis, we consider a polynomial system representing the cipher and a solution of this system reveals the secret key used in the encryption. The contribution of this thesis is twofold. Firstly, we evaluate the performance of existing algebraic techniques with respect to number of plaintext/ciphertext pairs and their selection. We introduce a new strategy for selection of samples. We build this strategy based on cube attacks, which is a well-known technique in algebraic cryptanalysis. We use cube attacks as a fast heuristic to determine sets of plaintexts for which standard algebraic methods, such as Groebner basis techniques or SAT solvers, are more efficient. Secondly, we develop a~new technique for algebraic cryptanalysis which allows us to speed-up existing Groebner basis techniques. This is achieved by efficient finding special polynomials called mutants. Using these mutants in Groebner basis computations and SAT solvers reduces the computational cost to solve the system. Hence, both our methods are designed as tools for building polynomial system representing a cipher. Both tools can be combined and they lead to a significant speedup, even for very simple algebraic solvers

Fast Key Recovery Attack on ARMADILLO1 and Variants

Part 3: New Algorithms and ProtocolsInternational audienceThe ARMADILLO cryptographic primitive is a multi-purpose cryptographic primitive for RFID devices proposed at CHES’10. The main purpose of the primitive is to provide a secure authentication in a challenge-response protocol. It has two versions, named ARMADILLO (subsequently denoted by ARMADILLO1) and ARMADILLO2. However, we found a fatal weakness in the design which allows a passive attacker to recover the secret key in polynomial time, of ARMADILLO1 and some generalizations. We introduce some intermediate designs which try to prevent the attack and link ARMADILLO1 to ARMADILLO2. Considering the fact that the attack against ARMADILLO1 is polynomial, this brings about some concerns into the security of the second version ARMADILLO2, although it remains unbroken so far