Cryptanalysis

Influence of the Linear Layer on the Algebraic Degree in SP-Networks

We consider SPN schemes, i.e., schemes whose non-linear layer is defined as the parallel application of t=1 independent S-Boxes over GF(2^n) and whose linear layer is defined by the multiplication with a nt x nt matrix over GF(2). Even if the …

Practical key recovery attacks on FlexAEAD

FlexAEAD is a block cipher candidate submitted to the NIST Lightweight Cryptography standardization project, based on repeated application of an Even-Mansour construction. In order to optimize performance, the designers chose a relatively small …

The Legendre Symbol and the Modulo-2 Operator in Symmetric Schemes over (F_p)^n

Motivated by modern cryptographic use cases such as multi-party computation (MPC), homomorphic encryption (HE), and zero-knowledge (ZK) protocols, several symmetric schemes that are efficient in these scenarios have recently been proposed in the …

Proving Resistance Against Infinitely Long Subspace Trails: How to Choose the Linear Layer

Designing cryptographic permutations and block ciphers using a substitution-permutation network (SPN) approach where the nonlinear part does not cover the entire state has recently gained attention due to favorable implementation characteristics in …

Mixture Integral Attacks on Reduced-Round AES with a Known/Secret S-Box

In this work, we present new low-data secret-key distinguishers and key-recovery attacks on reduced-round AES. The starting point of our work is “Mixture Differential Cryptanalysis” recently introduced at FSE/ToSC 2019, a way to turn the …

An Algebraic Attack on Ciphers with Low-Degree Round Functions: Application to Full MiMC

Algebraically simple PRFs, ciphers, or cryptographic hash functions are becoming increasingly popular, for example due to their attractive properties for MPC and new proof systems (SNARKs, STARKs, among many others). In this paper, we focus on the …

Algebraic Cryptanalysis of STARK-Friendly Designs: Application to MARVELlous and MiMC

The block cipher Jarvis and the hash function Friday, both members of the MARVELlous family of cryptographic primitives, are among the first proposed solutions to the problem of designing symmetric-key algorithms suitable for transparent, …

Forgery Attacks on FlexAE and FlexAEAD

FlexAEAD is one of the round-1 candidates in the ongoing NIST Lightweight Cryptography standardization project. In this note, we show several forgery attacks on FlexAEAD with complexity less than the security bound given by the designers, such as a …

Algebraic Cryptanalysis of Variants of Frit

Frit is a cryptographic 384-bit permutation recently proposed by Simon et al. and follows a novel design approach for built-in countermeasures against fault attacks. We analyze the cryptanalytic security of Frit in different use cases and propose …

Algebraic Cryptanalysis of Variants of Frit

Frit is a cryptographic 384-bit permutation recently proposed by Simon et al. and follows a novel design approach for built-in countermeasures against fault attacks. We analyze the cryptanalytic security of Frit in different use cases and propose …